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The benthic macrofauna of the mainland shelf of southern California

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The benthic macrofauna of the mainland shelf of southern California

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Content THE BENTHIC MACROFAUNA OF THE MAINLAND SHELF OF SOUTHERN CALIFORNIA by G i l b e r t F re d J o n e s A D i s s e r t a t i o n P r e s e n t e d t o th e FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA I n P a r t i a l F u l f i l l m e n t o f th e R e q u ire m e n ts f o r th e D egree DOCTOR OF PHILOSOPHY ( B io lo g y ) S ep tem b er 1967 UNIVERSITY O F SOUTHERN CALIFORNIA TH E GRADUATE SC H O O L UN IV ER SITY PARK LO S A N G ELES, C A L IF O R N IA 9 0 0 0 7 This dissertation, written by G i l b e r t F re d J o n e s under the direction of h.i-M—Dissertation Com mittee, and approved by all its members, has been presented to and accepted by the Graduate School, in partial fulfillment of requirements for the degree of D O C T O R OF P H I L O S O P H Y (2 _ ^ _ Dean D ate S ejp tember j 196 7 DISSERTATION COMMITTEE Chairman TABLE OP CONTENTS Page LIST OP TA B LE S ................................................................................................. v i LIST OF F I G U R E S ..................................................................................... . i x INTRODUCTION...................................................................................................... 1 The M arin e B i o t i c Community ................................................. 1 C o n c e p ts o f M arin e B e n th ic A nim al A s s o c i a t i o n s . 5 B i o l o g i c a l l y D e te rm in e d A s s o c i a t i o n s ( " B i o c o e n o s e s " ) ...................................................................... 6 E n v i r o n m e n t a l l y D e te rm in e d A s s o c i a t i o n s ( " B i o t o p e s " ) ................................................................................. 12 C o m b in a tio n A p p ro a c h e s ( " B i o c o e n o s i s and B i o t o p e " ) ...................................... 15 S t a t i s t i c a l D e s i g n a t i o n o f A s s o c i a t i o n s . . . 19 The P u rp o se o f t h i s I n v e s t i g a t i o n ................................. 21 The S tu d y A r e a ...................................................................................... 22 B e n t h i c S u rv e y s on t h e S o u th e r n C a l i f o r n i a n M a in la n d S h e l f ................................................................................. 34 Bays and H a r b o r s ........................................................................... 34 The SCUBA Z o n e ..................................................... 37 The M a in la n d S h e l f ...................................................................... 38 The A l l a n H ancock F o u n d a tio n S u rv ey o f th e S o u th e r n C a l i f o r n i a n M a in la n d S h e l f . . . . 41 M ethods o f S a m p lin g and A n a l y s i s ........................... 41 A Summary of th e R e s u l t s o f th e A l l a n H ancock F o u n d a tio n S u r v e y :, t h e B e n th ic M ac ro fa u n a . . 45 The R e p o r t s o f t h e A l l a n H ancock F o u n d a tio n S u rv e y ............................................................ 58 A cknow ledgem ents ................................................................................. 64 ii Page METHODS.................................................................................................................... 68 The A l l a n Hancock F o u n d a tio n S urvey Sam pling Program .......................................................................... 68 The G e n e ra l L i m i t a t i o n s o f th e B i o l o g i c a l D a ta . 78 D a ta and E l e c t r o n i c D ata P r o c e s s i n g ................................ 88 The D ata and D ata S o u r c e s ..................................................... 88 D a ta Tape P r e p a r a t i o n ................................................................ 90 D ata A n a l y s i s ..................................................................................... 93 Ranking Program .......................................................................... 93 REGROUP Program .......................................................................... 94 NTSYS (N u m e ric a l Taxonomy S ystem ) Program . . 97 U t i l i t y P rogram s ..................................................................... 100 S e l e c t i o n of a Sample S e t ................................................ 102 S ta n d a r d S t a t i s t i c a l T e c h n iq u e s ................................ 103 M ethods Summary ..................................................................................... 103 RESULTS............................................................................................................... . 105 S p e c ie s R anking ..................................................................................... 105 R an k in g W ith in S u b f i l e s ........................................................... 107 R anking By E n v ir o n m e n ta l V a r i a b l e s ...................... 112 R anking by Sample Volume ................................................ 115 R anking by B e n t h i c A s s o c i a t i o n s . . . . . . . 121 Summary D i s c u s s i o n ..................................................................... 133 S p e c ie s D i s t r i b u t i o n a l P a t t e r n s and M a c ro fa u n a l A s s o c i a t i o n s ..................................................... 136 Summary D i s c u s s i o n ..................................................................... 191 S p e c ie s G rouping ................................................................................ 195 R e c u r r e n t Group A n a l y s is ..................................................... 195 The M ain lan d S h e l f R e c u r r e n t Groups ...................... 198 The N o r th e r n S h e l f R e c u r r e n t Groups ...................... 230 The S a n ta B a r b a r a S h e l f (A re a I I ) R e c u r r e n t G roups ................................................................ 247 NYSYS r - M a t r i x C l u s t e r A n a l y s i s ..................................... 264 The NTSYS C l u s t e r A n a l y s i s o f th e N o r th e r n S h e l f S p e c ie s ................................................ 266 Group 2 c, T e l l i n a b u t t o n i and N o t h r i a e l e g a n s .................................... 269 Group 3c, D i o p a t r a o r n a t a ..................................... 275 Group 4 c , A m phiodia u r t i c a ; Group 4b, C a r d i t a v e n t n c o s a ; and Group 4 e , Pe c t in a r i'a ' c'a l'i f o r n i e n s i s and C h l o e i a p i n n a t a ................................................................ 276 Group 5 f , L i s t n o l o b u s p e l o d e s ........................... 285 I n t e r - g r o u p C o m p ariso n s ................................................ 289 iii Page The NTSYS C l u s t e r A n a l y s i s o f t h e S o u th e r n S h e l f S p e c i e s ................................................................... 294 Suimnary D i s c u s s i o n ...................................................................... 296 D I S C U S S I O N ............................................................................................................ 306 CONCLUSIONS..................................................................................... 315 APPENDIX A TABLES AND FIGURES OF THE TEXT . ........................................... 320 APPENDIX B ALLAN HANCOCK FOUNDATION SURVEY METHODS OF SAMPLING AND A N A LY SIS................................................................................. 363 B i o l o g i c a l M ethods ............................................................................ 363 B i o l o g i c a l S am pling E q u ip m en t and S am pling M e t h o d s ................................................................................................. 363 B i o l o g i c a l L a b o r a t o r y M ethods ........................................... 377 E n v ir o n m e n ta l S am p lin g M ethods and A n a l y s i s . . . 386 G e o l o g i c a l S am p lin g M ethods and A n a l y s i s . . . 386 H y d r o g ra p h ic Sam pling M ethods and A n a l y s i s . . 390 APPENDIX C THE SOUTHERN CALIFORNIAN MARINE R E G I O N ................................. 395 The C o n t i n e n t a l B o r d e r la n d . ................................................. 395 The C o a s t l i n e ............................................................................................ 401 The M a in la n d S h e l f ............................................................................ 404 A G e n e r a l C o n s i d e r a t i o n o f S e d im e n ts o f t h e M a in la n d S h e l f ................................................................................. 408 The N a tu r e and O r i g i n o f t h e S h e l f S e d im e n ts . 409 The G e n e r a l T e x tu r e o f t h e S h e l f S e d im e n ts . . 416 The C h e m ic a l P r o p e r t i e s o f S h e l f S e d im e n ts . . 441 A D e t a i l e d A c c o u n t o f t h e S e d im e n ts o f t h e S h e l f S u b d i v i s i o n s ...................................................................... 443 The P o i n t C o n c e p tio n S h e l f (A re a I ) .................. 444 The S a n t a B a r b a r a S h e l f (A re a I I ) ................................. 447 The Mugu S h e l f (A re a I I I ) .............................................. 456 The S a n ta M onica S h e l f (A re a IV)....................................... 457 The P a l o s V erd es S h e l f (A re a V).......................................... 461 The San P e d ro S h e l f (A re a V I ) ................................... 463 The N ew p o rt-L a J o l l a S h e l f (A re a V I I ) ...... 466 The San D iego S h e l f (A re a V I I I ) .......................................... 468 The N e a rs h o re S e d im e n ts ........................................................... 471 iv Page The W ater o v e r th e S o u th e r n C a l i f o r n i a B o r d e r la n d and t h e M a in la n d S h e l f ................................. 472 W ater M o t i o n ...................................................................................... 477 T r a n s p a r e n c y ...................................................................................... 478 T e m p e ra tu r e . . •................................................................................. 481 S a l i n i t y ................................ 486 D i s s o l v e d O x y g e n ............................., ........................................ 489 Common I n o r g a n i c N u t r i e n t s : P h o s p h a te , S i l i c a t e and N i t r a t e ............................................ 492 APPENDIX D A REVIEW OF THE BENTHIC MACROFAUNA OF THE MAINLAND S H E L F ................................................ 501 The O f f s h o r e F a u n a , Over 10 M e t e r s ................................. 501 The O f f s h o r e A s s o c i a t i o n s ........................................................... 508 The A m p h io d ia - C a r d i t a A s s o c i a t i o n ................................. 517 The A m phiodi a A s s o c i a t i o n ...................................................... 532 The Amphi od x a - Onuphi s and Q n u p h is A s s o c i a t i o n s ................................................................................. 534 The A m phioplus h e x a c a n t h u s A s s o c i a t i o n . . . . 539 The L i s t r i o l o b u s A s s o c i a t i o n ............................................ 545 The N o th r ia '-~Tel 1 j n a A s s o c i a t i o n ...................................... 553 The D i o p a t r a A s s o c i a t i o n ...................................................... 557 The N o t h r i a s t i g m a t i s - S p io p h a n e s bombyx A s s o c i a t i o n ....................................................................................... 561 The C h a e t o p t e r u s A s s o c i a t i o n ........................................... 562 Fauna o f t h e O u te r S h e l f and S l o p e ........................... 563 M inor A s s o c i a t i o n s ....................................................................... 564 The N e a r s h o r e F a u n a , 2 t o 10 M e t e r s ................................. 566 The N e a r s h o r e A s s o c i a t i o n s ...................................................... 570 "The S h a llo w - w a te r T e l l i n a F a c i e s ” o f t h e N o t h r i a - T e l l i n a A s s o c i a t i o n ............................................ 570 The P r i o n o s p i o m a lm g re n i A s s o c i a t i o n ...................... 571 REFERENCES . . . ...................................................................................... 577 v LIST OF TABLES Table Page 1. A re a o f D ep th C l a s s e s f o r th e E i g h t G e o g ra p h ic A r e a s - - t h e B a s i s f o r th e S t r a t i f i e d S am pling S ystem D e v e lo p e d by J . L a u re n s B a rn a rd . . . . 75 2 . The R e l a t i o n s h i p o f Sample S u r fa c e t o Sample V o l u m e ...................................................................................................... 83 3. The E f f e c t i v e n e s s o f th e S y s t e m a t i c A n a l y s i s by th e A l l a n H ancock F o u n d a tio n S t a f f . . . . 87 4 . A L i s t o f th e S p e c i e s Common t o th e T h ree L i s t s o f th e 50 T o p -ra n k e d S p e c i e s a s O rd e re d by F re q u e n c y o f O c c u r r e n c e , P o p u l a t i o n D e n s i t y and Number o f A f f i n i t i e s ........................................... 110 5. Summary o f t h e R e s u l t s o f R anking A n a ly s e s by E n v ir o n m e n ta l V a r i a b l e s ...................................... . . . 116 6. S p e c i e s R a n k in g s by A s s o c i a t i o n s .................................. 123 7 . The S p e a rm a n ’ s V a lu e s and jt V a lu e s f o r th e R a n k in g s by A s s o c i a t i o n S u b f i l e s ................................. 129 8. C o m p ariso n o f S e d im e n t V a r i a b l e s o f N o t h r i a - S p io p h a n e s A s s o c i a t i o n and th e M ain la n d S h e l f . .......................................................... 131 9. C o m p ariso n o f S ed im en t V a r i a b l e s o f th e L i s t r i o l o b u s A s s o c i a t i o n and th e M ain lan d S h e l f . . ...................................................................................... 132 10. The R e c u r r e n t G roups o f th e M ain la n d S h e l f B ased on t h e A n a l y s i s o f th e 176-S am ple S e t . 199 11. S ed im en t D a ta f o r Group I I - V S t a t i o n s from t h e S a n ta B a r b a r a S h e l f and S lo p e i n Itfater D e p th s >91 M e t e r s ...................................................................... 220 vi Table Page 12. The R e c u r r e n t Groups o f th e M ain lan d S h e l f , B ased on th e A n a l y s i s o f t h e 176-Sam ple S e t , D i s t r i b u t e d by th e B e n th ic A s s o c i a t i o n S u b f i l e s 222 13. The R e c u r r e n t G roups o f th e N o r th e r n S h e lf B ased on th e A n a l y s is o f th e 74 Sam ples o f t h e 176-Sam ple S e t from t h i s R e g i o n ...................... 232 14. The R e c u r r e n t Groups o f th e S a n ta B a rb a ra S h e l f Based on th e A n a l y s i s o f th e 176- Sample S e t .......................................................................................... 248 15. Summary o f Group D i s t r i b u t i o n by M ajor A s s o c i a t i o n on S a n ta B a r b a r a S h e l f ........................... 261 16. Summary o f th e E n v ir o n m e n ta l and S ta n d in g C rop V a r i a b l e s f o r Groups SB-X I, SB-X, and SB-XIV D e riv e d from th e R e c u r r e n t Group A n a l y s i s o f th e Samples from th e S a n ta B a r b a r a S h e l f ................................................................................ 262 17. S p e c ie s t h a t C o r r e l a t e w i t h T e l l i n a b u t t o n i a n d / o r N o t h r i a e l e g a n s above th e 0 . 4U0 l e v e l b u t a r e Members o f G roups o t h e r th a n Group 2c .......................................................................................... 274 18. A L i s t o f th e S p e c ie s t h a t C o r r e l a t e w ith A m phiodia u r t i c a above th e 0 .4 0 0 L e v el . . . . 280 19. A Summary o f th e D egree o f C o r r e l a t i o n Between Some o f t h e G roups o f th e N o r th e r n S h e l f D e n d r o g r a m .......................................................................... 290 2 0. G roup 3c D e riv e d by th e NTSYS r - M a t r i x C l u s t e r i n g A n a l y s i s o f th e S o u th e rn S h e l f . . 297 A ppendix T a b le Page A - l . The O r i g i n a l S t r a t i f i e d Sample o f 176 S a m p l e s ............................................................................................... 321 A -2. D ata Card Form at 340 A p p en d ix Page T a b le A - 3 . A s s o c i a t i o n s and " D o m in a n ts” a s D e s i g n a t e d by D r. J . L a u re n s B a rn a rd d u r i n g t h e Allan. H ancock F o u n d a tio n S u rv e y o f th e M a in la n d S h e l f ..................................................................................................................344 A - 4 . D a ta Tape R ec o rd Form at w i t h D e s c r i p t i o n o f V a r i a b l e s ....................................................................................................... 349 A - 5 . The R e v is e d S t r a t i f i e d Sample o f 176 S am p les . 352 A -6 . The 50 T o p -ra n k e d S p e c ie s i n th e 176-Sam ple S e t a s Ranked by F re q u e n c y o f O c c u rre n c e ( C a p t u r e ) ....................................................................................................... 354 A -7 . The 50 T o p - r a n k e d S p e c i e s i n th e 176-S am ple S e t a s Ranked by P o p u l a t i o n D e n s i ty .. .. .. 357 A -8 . The 50 T o p - r a n k e d S p e c i e s i n th e 176-S am ple S e t a s Ranked by th e Number o f A f f i n i t i e s w i t h O th e r S p e c i e s o f t h e Sample S e t .............................360 B - l . S t a t i o n R ec o rd S h e e t ................................................................ 375 B -2 . L a b o r a t o r y R ec o rd S h e e ts ..................................................... 379 D - l . The Most A bundant A n im als o f th e O f f s h o r e B o tto m A r e a s , D eeper t h a n 1 0 .1 M e t e r s .............................506 viii LIST OF FIGURES Figure Page 1. A Map o f t h e S o u th e rn C a l i f o r n i a n C o n t i n e n t a l B o r d e r la n d Showing th e M a in la n d S h e l f , th e O f f s h o r e B a s i n s , th e O f f s h o r e I s l a n d s , and t h e P a t t o n E s c a rp m e n t ........................................................... 24 2 . A r e a l D i s t r i b u t i o n o f B otto m M a t e r i a l on th e N o r t h e r n S e c t i o n o f t h e M a in la n d S h e l f ( P o i n t A r g u e l l o t o P o i n t Dume) ...................................................... 27 3. A r e a l D i s t r i b u t i o n o f B ottom M a t e r i a l on t h e C e n t r a l S e c t i o n o f th e M a in la n d S h e l f ( P o i n t Dume to C orona d e l M a r ) ...................................................... 29 4 . A r e a l D i s t r i b u t i o n o f B o tto m M a t e r i a l on th e S o u th e r n S e c t i o n o f th e M a in la n d S h e l f (C o ro n a d e l Mar t o San D i e g o ) ...................................... 31 5 . The D i s t r i b u t i o n o f B e n t h i c M a c r o f a u n a l A s s o c i a t i o n s on th e M a in la n d S h e l f , P o i n t A r g u e l l o ( P o i n t C o n c e p tio n ) t o S a n t a B a r b a r a ................................................................................................. 46 6. The D i s t r i b u t i o n o f B e n th ic M a c r o f a u n a l A s s o c i a t i o n s on th e M a in la n d S h e l f , S a n ta B a r b a r a t o P o i n t D u m e ................................................; . . 48 7. The D i s t r i b u t i o n o f B e n t h i c M a c ro f a u n a l A s s o c i a t i o n s on th e M ain lan d S h e l f , P o i n t Dume t o N e w p o r t ............................................................................ 53 8. The D i s t r i b u t i o n o f B e n t h i c M a c ro f a u n a l A s s o c i a t i o n s on th e M a in la n d S h e l f , N ew port t o M e x i c o ............................................................................................ 55 9. A Map o f t h e M a in la n d S h e l f o f S o u th e r n C a l i f o r n i a Showing t h e E i g h t G e o g ra p h ic D i v i s i o n s ( o r A r e a s ) ............................................................ 72 ix Figure 1 0 a - lO d. 1 1 - 5 4 . 55. 56. 57. 58. 59. 60. 61. P o p u l a t i o n D e n s i t y P l o t s f o r 38 S e l e c t e d S p e c i e s fro m t h e N o t h r i a - T e l l i n a , L i s t r i o - lo b u s and A m p h io d ia - C a r d i t a A s s o c i a t i o n s o f t h e S a n t a B a r b a r a S h e l f A r r a n g e d b y D e p th - - A S e r i e s o f 44 S p e c i e s D e n s i t y D i s t r i b u t i o n s P l o t t e d a t 55 S a m p lin g L o c a t i o n s o f t h e S a n t a B a r b a r a A r e a A r r a n g e d on a G ra p h D e f i n e d b y a S e d im e n t V a r i a b l e , M ed ia n D i a m e t e r i n M ic r o n s , and by D e p th i n M e te r s . A D ia g r a m m a tic R e p r e s e n t a t i o n o f t h e I n t e r r e l a t i o n s h i p o f th e R e c u r r e n t G ro u p s o f t h e M a in la n d S h e l f B a se d on I n t e r - G r o u p A f f i n i t i e s ......................................................................................... The G e o g r a p h ic D i s t r i b u t i o n o f t h e R e c u r r e n t G ro u p s o f t h e M a in la n d S h e l f on t h e N e w p o rt- La J o l l a S h e l f (L a g u n a t o La J o l l a ) ........................ The G e o g r a p h ic D i s t r i b u t i o n o f t h e R e c u r r e n t G ro u p s o f th e M a in la n d S h e l f on t h e San P e d r o Bay S h e l f ( W h i te s P o i n t t o C o ro n a d e l M ar) .............................................................................................. The G e o g r a p h ic D i s t r i b u t i o n o f t h e R e c u r r e n t G ro u p s o f t h e M a in la n d S h e l f on t h e S a n t a B a r b a r a S h e l f ( S a n t a B a r b a r a t o Mugu) . . . . A G rap h o f t h e Number o f S p e c i e s o f M a in la n d S h e l f R e c u r r e n t G ro u p s I I and V A g a i n s t t h e Number o f S p e c i e s o f G ro u p s I , I I I , IV and VI f o r t h e A m p h io d ia and A m p h io d ia - C a r d i t a A s s o c i a t i o n s ................................................................................... A G rap h o f t h e Number o f S p e c i e s o f M a in la n d S h e l f R e c u r r e n t G ro u p s I I and V A g a i n s t t h e Number o f S p e c i e s o f G ro u p s I , I I I , IV and VI f o r t h e N o t h r i a - T e l l i n a and D i o p a t r a A s s o c i a t i o n s ................................................................................... A D ia g r a m m a tic R e p r e s e n t a t i o n o f th e I n t e r r e l a t i o n s h i p o f t h e R e c u r r e n t G ro u p s o f t h e N o r t h e r n S h e l f B a se d on I n t e r - G r o u p A f f i n i t i e s ......................................................................................... Page 138 145 203 212 214 217 225 227 237 x F ig u r e Page' 62. The G e o g ra p h ic D i s t r i b u t i o n o f th e R e c u r r e n t G roups o f th e N o r t h e r n S h e l f on th e S a n t a B a r b a r a S h e l f ( S a n t a B a r b a r a t o Mugu) . . . . 244 63. A D ia g ra m m a tic R e p r e s e n t a t i o n o f t h e I n t e r r e l a t i o n s h i p o f th e R e c u r r e n t G roups o f t h e S a n ta B a r b a r a S h e l f B ased on I n t e r - G r o u p A f f i n i t i e s ...................................................................................... 254 6 4 . The G e o g ra p h ic D i s t r i b u t i o n o f th e R e c u r r e n t G roups of t h e S a n ta B a r b a r a S h e l f fro m S a n ta B a r b a r a t o Hueneme Subm arine Canyon ( S a n t a B a r b a r a to M u g u ) ...................................................................... 258 6 5. B ran ch Two o f t h e N o r t h e r n S h e l f D endrogram . 270 6 6 . B ran ch Four o f th e N o r th e r n S h e l f D e n d r o g r a m ...................................................................................... 277 6 7 . B ran ch F ive o f th e N o r th e r n S h e l f D e n d r o g r a m ...................................................................................... 287 A p p e n d ix F ig u r e Page A - l . A Map Showing th e L o c a t i o n s o f th e F o u r te e n C h a r t s I l l u s t r a t i n g t h e A l l a n H ancock F o u n d a tio n S u rv e y S t a t i o n L o c a t i o n s ..................... 323 A -2 - C h a r t s o f t h e A l l a n H ancock F o u n d a tio n A -1 5 . S u rv ey S t a t i o n L o c a t i o n s ................................................. 325 B - l . a) M o d if ie d l / l O S q u a re M e te r Van Veen Grab Shown w i t h Jaw s Open b) Hayward S ta n d a r d O r a n g e - P e e l B u c k e t (Open) c ) Hayward S ta n d a r d O r a n g e - P e e l B u ck e t (Open on d e c k show ing t r i p m echanism ) d) Hayward S ta n d a r d O r a n g e - P e e l B u ck e t ( C l o s e d ) .................................... % ............................................. 365 B -2 . a) M e c h a n ic a l S h ak er w ith G rad ed S c r e e n s A board th e R /v V e le r o IV Viewed fro m th e S id e b) M e c h a n ic a l S h ak er w i t h G raded S c r e e n s Viewed fro m A b o v e ........................................................... 370 xi Appendix Figure Page C - l . A M ap-of th e S o u t h e r n C a l i f o r n i a n C o n t i n e n t a l B o r d e r l a n d Show ing th e M a in la n d S h e l f , the'- O f f s h o r e B a s i n s , th e O f f s h o r e I s l a n d s , and t h e P a t t o n E s c a rp m e n t ........................................................... 398 C -2 . A G e n e r a l Map o f t h e S o u th e rn C a l i f o r n i a n C o a s t a l A re a Showing th e M a in la n d S h e l f , t h e P r i n c i p a l S tu d y A re a . . . ...................................... 405 C -3 . A H is to g r a m o f Sand C o n te n t Showing th e P er c e n t o f t h e T o t a l S am ples i n Each 10 p e r c e n t I n c re m e n t o f Sand C o n t e n t ................................ 418 C -4 . A H is to g r a m o f S i l t C o n te n t Showing th e Per c e n t o f t h e T o t a l S am p les i n Each 10 per c e n t I n c r e m e n t o f S i l t C o n t e n t ............................... 421 C -5 . A H is to g r a m o f C la y C o n t e n t Showing th e P er c e n t o f t h e T o t a l Sam ples i n Each 2 P e r c e n t I n c r e m e n t o f C la y C o n t e n t ................................ 423 C -6 . A G r a v e l - S a n d - S i l t S e d im e n t-T y p e T r i a n g u l a r D iagram w ith D e s c r i p t i v e N a m e s ................................. 426 C -7 . A r e a l D i s t r i b u t i o n o f B ottom M a t e r i a l on th e N o r th e r n S e c t i o n o f t h e M a in la n d S h e l f ( P o i n t A r g u e l l o t o P o i n t Dume) ................................. 428 C -8 . A r e a l D i s t r i b u t i o n o f B o tto m M a t e r i a l s on t h e C e n t r a l S e c t i o n o f t h e M a in la n d S h e lf ( P o i n t Dume t o C o ro n a d e l M a r ) ................................. 430 C -9 . A r e a l D i s t r i b u t i o n o f B otto m M a t e r i a l s on t h e S o u th e r n S e c t i o n o f t h e M a in la n d S h e l f (C o ro n a d e l Mar t o San D i e g o ) ...................................... 432 C -1 0 . A H is to g r a m o f G ra in S iz e Showing t h e P er c e n t o f t h e T o t a l S am ples f o r Each M edian D ia m e te r I n c re m e n t ................................................................. 437 C - l l . D i s t r i b u t i o n o f Woody D e b r i s on t h e S h e l f o f f V e n t u r a ...................................................................................... 453 C -1 2 . S u r f a c e C u r r e n t s o f t h e S o u th e r n C a l i f o r n i a Sea E x p r e s s e d D i a g r a m m a t ic a l ly ................................. 474 xii Appendix Figure Page C -1 3 . Y e a r ly Mean V i s u a l T r a n s p a r e n c y o f S o u th e rn C a l i f o r n i a n C o a s t a l W a te rs as M easu red by t h e S e c c h i D i s c ...................................................................................... 479 C -1 4 . L a t i t u d i n a l D i s t r i b u t i o n o f Mean T e m p e ra tu re by S e a s o n s on th e M a in la n d S h e l f o f S o u th e rn ... C a l i f o r n i a ........................................................................................ 483 C -1 5 . L a t i t u d i n a l D i s t r i b u t i o n o f Mean S a l i n i t y by S e a so n s on t h e M a in la n d S h e l f o f S o u th e rn C a l i f o r n i a ...................................................................................... 487 C -16. L a t i t u d i n a l D i s t r i b u t i o n o f Mean D is s o lv e d Oxygen by S e a s o n s on t h e M a in la n d S h e l f o f S o u th e rn C a l i f o r n i a ................................................................. 490 C -1 7 . L a t i t u d i n a l D i s t r i b u t i o n o f Mean P h o s p h a te by S e a s o n s on th e M a in la n d S h e l f o f S o u th e r n C a l i f o r n i a ...................................................................................... 493 C -18. L a t i t u d i n a l D i s t r i b u t i o n o f Mean S i l i c a t e by S e a s o n s on t h e M a in la n d S h e l f o f S o u th e rn C a l i f o r n i a ...................................................................................... 497 D - l . The D i s t r i b u t i o n o f B e n t h i c M a c r o f a u n a l A s s o c i a t i o n s on th e M a in la n d S h e l f , P o i n t A r g u e l l o t o S a n ta B a r b a r a ................................................. 509 D - 2 . The D i s t r i b u t i o n o f B e n t h i c M a c ro f a u n a l A s s o c i a t i o n s on th e M a in la n d S h e l f , S a n ta B a r b a r a t o P o i n t D u m e ............................................................ 511 D -3. The D i s t r i b u t i o n o f B e n t h i c M a c ro f a u n a l A s s o c i a t i o n s on th e M a in la n d S h e l f , P o i n t Dume t o N e w p o r t ............................................................................ 513 D -4. The D i s t r i b u t i o n o f B e n t h i c M a c r o f a u n a l A s s o c i a t i o n s on th e M a in la n d S h e l f , New port to M e x i c o ............................................................................................ 515 D -5. A Map o f th e S o u th e rn C a l i f o r n i a n M ain lan d S h e l f Showing th e A r e a s P o p u l a t e d by O p h iu ro id A s s o c i a t i o n s ...................................................... 518 D -6 . A Map Showing t h e D i s t r i b u t i o n o f th e A m p h io d ia - C a r d i t a A s s o c i a t i o n on t h e S a n ta B a r b a r a S h e l f . T ...................................................................... 520 xiii Appendix Figure D -7 . A Map Showing th e D i s t r i b u t i o n o f th e A m phiodia A s s o c i a t i o n on t h e S a n ta M onica Bay S h e l f and t h e P a lo s V erd es S h e l f ...................... D -8 . D i s t r i b u t i o n o f th e A m phioplus h e x a c a n th u s A s s o c i a t i o n on th e San P ed ro Bay S h e lf I T . . D -9. D i s t r i b u t i o n o f th e A m phiodia A s s o c i a t i o n on t h e San D ieg o S h e l f ^ ! ! ........................................... D -10. A Map Showing th e D i s t r i b u t i o n o f M o llu s c a n S ta n d in g C rop on th e P o in t C o n c e p tio n S h e l f D - l l . A P i c t o r i a l R e p r e s e n t a t i o n o f th e A m p h io d ia- C a r d i t a A s s o c i a t i o n on th e S a n ta B a r b a r a S h e l f West o f Hueneme Subm arine Canyon . . . . D -12. A P i c t o r i a l R e p r e s e n t a t i o n o f t h e A m phiodia u r t i c a A s s o c i a t i o n on th e M a in la n d S h e l f S o u t h e a s t o f Hueneme Subm arine Canyon . . . . D -13. A P i c t o r i a l R e p r e s e n t a t i o n o f th e A m phioplus h e x a c a n th u s A s s o c i a t i o n on t h e San P e d ro Bay S h e l f .......................................................................... . . . D -14. A Map Showing th e D i s t r i b u t i o n o f L i s t r i o l o b u s p e l o d e s S ta n d in g Crop on th e S a n ta B a r b a r a She I f ..................................................................................................... D -15. A D ia g ra m m a tic R e p r e s e n t a t i o n o f th e I n h a b i t a n t s of a O n e -Q u a rte r S quare M e te r P l o t o f t h e L i s t r i o l o b u s A s s o c i a t i o n ........................................... D -16. A P i c t o r i a l R e p r e s e n t a t i o n o f t h e N o t h r i a - T e l l i n a A s s o c i a t i o n i n D ep th s o f 30-95 F e e t D -1 7 . A P i c t o r i a l R e p r e s e n t a t i o n o f th e N o t h r i a - T e l l i n a A s s o c i a t i o n i n D ep th s o f 38-92 F e e t D -18. A P i c t o r i a l R e p r e s e n t a t i o n o f t h e N o t h r i a - T e l l i n a A s s o c i a t i o n i n D ep th s o f 12-30 F e e t D -19. A P i c t o r i a l R e p r e s e n t a t i o n o f t h e P r i o n o s p i o A s s o c i a t i o n i n D ep th s o f 12-30 F e e t ...................... Page 520 522 522 525 529 535 543 546 549 555 558 572 575 xiv INTRODUCTION The M arin e B i o t i c Community The com m unity c o n c e p t i s one o f t h e m ost i m p o r t a n t i n e c o lo g y (Odum, 1 9 5 9 ). A b i o t i c com m unity i s an a s se m b l a g e o f p o p u l a t i o n s l i v i n g i n a p r e s c r i b e d a r e a o r p a r t i c u l a r p h y s i c a l h a b i t a t ; i t d e m o n s t r a t e s a ta x o n o m ic u n i t y i n t h a t c e r t a i n o r g a n is m s t e n d to o c c u r t o g e t h e r ; i t h a s c h a r a c t e r i s t i c s a d d i t i o n a l t o t h o s e o f i t s i n d i v i d u a l com ponent p o p u l a t i o n s ; i t h a s a d e f i n i t e f u n c t i o n a l u n i t y b a s e d upon i t s t r o p h i c s t r u c t u r e and th e t r a n s f e r o f e n e r g y t h r o u g h th e community (Odum, 1 9 5 9 ). I n a s e n s e a com m unity i s a p e r p e t u a l s tr e a m o f m a t t e r and e n e r g y t h a t a t t h e same tim e c o n s t i t u t e s th e community and p a s s e s t h r o u g h i t ( B e r t a l a n f f y , 1950; F a g e r , 1 9 6 3 ). T h e se i d e a s a r e sum m arized i n t h e c o n c i s e d e f i n i t i o n o f t h e b i o t i c com m unity r e s u l t i n g fro m Odum’ s amendment to i t s d e f i n i t i o n by V i c t o r E. S h e l f o r d : a b i o t i c community i s an " a s s e m b la g e w i t h u n i t y o f ta x o n o m ic c o m p o s itio n and r e l a t i v e l y u n if o r m a p p e a r a n c e . . . and w ith a d e f i n i t e t r o p h i c o r g a n i z a t i o n and m e t a b o l i c p a t t e r n " (Odum, 1959, p . 2 4 6 ) . The com m unity o f o r g a n is m s i s a d i v e r s e g ro u p o f e n e r g y t r a n s f o r m e r s a r r a n g e d i n a t r o p h i c s t r u c t u r e . The p h o t o s y n t h e t i c p o p u l a t i o n s ( a u t o t r o p h s ) a r e t h e " p r i m a r y p r o d u c e r s " r e s p o n s i b l e f o r th e c o n v e r s i o n o f th e s u n ’ s r a d i a n t e n e r g y t o b i o l o g i c a l l y u s e f u l f o r m s . The com m unity d o m in a n ts a r e members o f t h i s a b s o l u t e l y e s s e n t i a l t r o p h i c l e v e l (Odum, 1 9 5 9 ). A com m unity d o m in a n t s p e c i e s i s a p h o t o s y n t h e t i c form o f s u c h im p o r ta n c e t h a t i t c o n t r o l s t h e e n e r g y f lo w o f t h e com m unity. W ith in a s i n g l e com m unity e c o l o g i c a l dom in an ce may be s h a r e d by s e v e r a l s p e c i e s . Com m u n i t i e s a r e o f t e n named f o r and r e c o g n i z e d by t h e e c o l o g i c a l l y d o m in a n t o r g a n is m s (Odum, 1 9 5 9 ). The n o n - p h o t o s y n t h e t i c o r g a n is m s ( h e t e r o t r o p h s ) , th e c o n su m e rs and d e c o m p o s e rs , f u n c t i o n a t o t h e r l e v e l s i n th e t r o p h i c s t r u c t u r e . At e a c h t r o p h i c l e v e l one o r more s p e c i e s may l a r g e l y c o n t r o l t h e e n e r g y f l o w and be te rm e d a t r o p h i c l e v e l d o m in a n t (Odum, 1 9 5 9 ). I f t h e c o n c e p t o f th e b i o t i c com m unity and i t s c o r o l l a r i e s o f community d o m in a n ts and t r o p h i c l e v e l d o m in a n ts a r e a p p l i e d t o t h e s e a t h e r e s u l t i s a b i o t i c com m unity v e r t i c a l l y d i s t r i b u t e d i n t h e w a t e r colum n. In t h e s e a th e m a jo r p h o t o s y n t h e t i c o r g a n is m s , t h e p h y t o p l a n k t o n , a r e l i m i t e d to a r e l a t i v e l y t h i n l a y e r b e n e a t h t h e s u r f a c e , th e p h o t i c z o n e , and th e h e t e r o t r o p h s a r e v a r i o u s l y d i s t r i b u t e d i n t h e w a te r colum n and i n th e s u b s t r a t e b e n e a t h . The e x i s t e n c e o f su c h v e r t i c a l l y d i s t r i b u t e d b i o t i c c o m m u n itie s i n t h e m a rin e e c o s y s te m i s s u p p o r t e d by kno w led g e o f fo o d c y c l e s i n t h e s e a (M are, 1942; S v e r d r u p , J o h n s o n and F le m in g , 1942; and H e d g p e th , 1 9 5 7 a ) . F ix ed m a r in e p l a n t s , a t t a c h e d a l g a e and n o n - a l g a l m a rin e p l a n t s , i m p o r t a n t l o c a l l y a t s h a l l o w d e p t h s p r o v id e m a r in e b i o t i c c o m m u n itie s more a k i n to t h o s e o f t h e t e r r e s t r i a l e n v ir o n m e n t. M a rin e c o m m u n itie s d o m in a te d by p h y t o p l a n k t o n s p e c i e s , and d i s t r i b u t e d t h r o u g h t h e e n t i r e w a t e r column and e x t e n d i n g i n t o t h e b e n t h i c s e d i m e n t s , a re c o n s i s t e n t t h e o r e t i c a l l y w i t h th e b i o t i c com m unity c o n c e p t. In d e e d t h i s ty p e o f com m unity i s t h e b a s i c c o m m u n ity -ty p e o f th e m a rin e e c o s y s te m (M a re , 1942; H a rd y , 1950; S v e r d ru p , Jo h n so n and F le m in g , 1 9 4 2 ) . U n f o r t u n a t e l y i t d o e s n o t p r o v i d e a p r a c t i c a l s tu d y u n i t . . I t i s f a r to o com plex. 'W hile i t may be f e a s i b l e t o d i f f e r e n t i a t e p h y t o p l a n k t o n a s s o c i a t i o n s a s a b a s i s f o r d i s t i n g u i s h i n g c o m m u n itie s in th e s e a , th e t a s k of r e l a t i n g t h e s e t o th e g r o u p s o f co n su m ers and d e c o m p o se rs a t t h e v a r i o u s l e v e l s i n t h e w a te r colum n and i n th e s e d im e n ts i s n e a r l y i m p o s s i b l e . H o r i z o n t a l and v e r t i c a l w a te r m ove m en ts d i s t o r t th e t h e o r e t i c a l v e r t i c a l d i s t r i b u t i o n o f t h e com ponents o f t h e s e m a rin e b i o t i c c o m m u n itie s . The i n t e r r e l a t i o n s h i p s among such c o m m u n itie s w ould be d i f f i c u l t t o a s s e s s . H e d g p e th (1 9 5 7 a , p . 30) has o b s e r v e d t h a t nNo com m unity o f o r g a n is m s in t h e s e a i s com p l e t e l y i n d e p e n d e n t , and some a r e so i n t i m a t e l y r e l a t e d . . . t h a t i t i s i m p o s s i b l e to s e p a r a t e t h e m . ” He h a s f u r t h e r p o i n t e d o u t t h a t i n th e s e a th e i n t e r d e p e n d e n c i e s among c o m m u n itie s a r e more p ro n o u n c e d th a n on la n d and t h a t t o u n d e r s t a n d e c o l o g i c a l p r o c e s s e s i n th e s e a one m ust d e a l w i t h i n t e r r e l a t e d s y s te m s r a t h e r t h a n d i s c r e t e c o m m u n itie s . The p a r t i c u l a r n a t u r e o f m a rin e b i o t i c c o m m u n itie s i s r e l a t e d t o t h e v e r y l a r g e , c o n s t a n t l y m oving, d e n s e f l u i d medium t h a t i s t h e p r i n c i p a l com ponent o f t h e i r e n v ir o n m e n t. ... T r a d i t i o n a l l y m a rin e e c o l o g i s t s have s t u d i e d s e l e c t ed f r a c t i o n s o f m a rin e c o m m u n itie s d e l i m i t e d by a v a r i e t y o f c r i t e r i a . Such t y p i c a l s u b d i v i s i o n s o f th e b i o t a a s p h y t o p l a n k t o n , z o o p l a n k t o n , b a t h y p e l a g i c f i s h e s , b e n t h i c m a c ro f a u n a , b e n t h i c m e io f a u n a , b e n t h i c f o r a m i n i f e r a n s , e t c . , r e p r e s e n t h o r i z o n t a l t r a n s e c t s w i t h i n th e g e n e r a l v e r t i c a l o r i e n t a t i o n o f m a rin e b i o t i c c o m m u n itie s . T h e se s u b d i v i s i o n s may be f u r t h e r d i v i d e d i n t o l o c a l i z e d g r o u p in g s o f o rg a n is m s te rm e d a s s o c i a t i o n s . The a s s o c i a t i o n a p p r o a c h i s a l e s s d e s i r a b l e mode o f e c o l o g i c a l i n q u i r y t h a n t h e s t u d y o f th e b i o t i c com m unity as a u n i t . N e v e r t h e l e s s , i t i s l i k e l y t h a t m a rin e e c o l o g i s t s w i l l have t o c o n t i n u e t o work w i t h i n i t s l i m i t a t i o n s i n p u r s u i n g s o l u t i o n s t o t h e p ro b le m s e n c o u n t e r e d i n th e s e a . The d i s t i n c t i o n b e tw e e n some m a rin e a s s o c i a t i o n s , su ch a s t h o s e o f th e b e n t h i c m a c ro fa u n a and b e n t h i c m e io f a u n a , i s made on th e b a s i s o f t e c h n i c a l r a t h e r t h a n e c o l o g i c a l c r i t e r i a . The m eta z o a n i n v e r t e b r a t e s p e c i e s o f th e u n c o n s o l i d a t e d s e d im e n ts on t h e s e a f l o o r hav e b e e n a r b i t r a r i l y a l l o t t e d to two g r o u p s , t h e m a c ro fa u n a and th e m e io f a u n a , on t h e b a s i s o f s i z e (M are, 1 9 4 2 ). U s u a l l y th e a n im a l a s s o c i a t i o n s o f t h e s e two s u b d i v i s i o n s a r e s t u d i e d s e p a r a t e l y (W ig le y and M c I n t y r e , 1 9 6 4 ). The p r e s e n t p a p e r i s c o n c e r n e d o n ly w i t h th e s t u d y o f t h e b e n t h i c m a c ro fa u n a o f th e m a in la n d s h e l f o f s o u t h e r n C a l i f o r n i a . C o n c e p ts o f M arin e B e n t h i c A nim al A s s o c i a t i o n s C o m p re h e n siv e r e v i e w s o f work i n m a rin e e c o lo g y d e a l i n g w i t h b e n t h i c m a c ro fa u n a a re p r o v id e d by N. S. J o n e s ( 1 9 5 0 ) , T h o rs o n ( 1 9 5 7 ) , Z e n k e v i tc h (1 9 6 3 ) and L o n g h u r s t ( 1 9 6 4 ) . T h e i r r e v i e w s w i l l n o t be r e s t a t e d h e r e . The d i s c u s s i o n w hich f o l l o w s su m m arizes s e l e c t e d p a p e r s i l l u s t r a t in g t h e d i v e r g e n t c o n c e p t s a p p l i e d by m a rin e e c o l o g i s t s t o th e p ro b le m s o f d e s c r i b i n g , n am in g , d e f i n i n g and c l a s s i f y in g b e n t h i c m a c r o f a u n a l a s s o c i a t i o n s . O fte n t h e s e a s s o c i a t i o n s w ere te rm e d " c o m m u n i t ie s , ,f and i d e a s w ere a p p l i e d t o them t h a t p r o p e r l y s h o u ld be r e s e r v e d f o r b i o t i c communi t i e s . L o n g h u r s t (1 9 6 4 ) p o i n t s o u t t h a t a b a s i c p ro b le m i n b e n t h i c e c o l o g y i s t h e f a c t t h a t th e m a rin e e c o l o g i s t l a c k s su c h a s im p le s t a r t i n g p o i n t a s l a n d s c a p e . A c c o r d i n g l y t h e r e h a s b e e n a l a c k o f a g re e m e n t a s t o t h e b a s i s f o r c l a s s i f i c a t i o n . He h a s s t a t e d t h i s p r o b le m in t h e f o l l o w in g w o rd s : As w i t h t h e a c t u a l u n i t s o f c l a s s i f i c a t i o n , so t h e r e i s l i t t l e a g re e m e n t on w hat t h e c l a s s i f i c a t i o n s h o u ld b e b a s e d - - t h e main d i v e r g e n c e b e in g b e tw e e n t h e p r o t a g o n i s t s o f a c l a s s i f i c a t i o n b a s e d p r i m a r i l y on th e d e p o s i t s , and th o s e o f a c l a s s i f i c a t i o n b a s e d upon c h a r a c t e r i s t i c e l e m e n ts o f t h e f a u n a - - a s H ed g p eth (1 9 5 4 ) p u t i t : b i o t o p e v e r s u s b i o c o e n o s i s ( p . 1 3 ). I n t i m a t e l y r e l a t e d t o t h e p ro b le m s o f t h e d e f i n i t i o n and . c l a s s i f i c a t i o n o f a s s o c i a t i o n s a r e t h o s e o f t h e i r i d e n t i f i c a t i o n and nam ing. Those w r i t e r s who b a s e t h e i r sy ste m p r i m a r i l y on t h e s p e c i e s c o m p o s itio n em ploy ’’t y p e " or " d o m in a n t" s p e c i e s a s th e means o f r e c o g n i t i o n and nam ing ( T h o r s o n , 1 9 5 7 ) . An a l t e r n a t i v e m ethod i s t o i d e n t i f y and name a s s o c i a t i o n s on th e b a s i s o f th e c h a r a c t e r i s t i c s o f t h e e n v ir o n m e n t t h e y i n h a b i t (N. S. J o n e s , 1 9 5 0 ). The c o n c e p t u a l i z a t i o n s i n v o l v e d i n d e f i n i t i o n , c l a s s i f i c a t i o n , and nam in g a r e s u f f i c i e n t l y i n t e r d e p e n d e n t i n a s s o c i a t i o n e c o lo g y t h a t i t i s d i f f i c u l t t o a n a ly z e any c a u s e - a n d - e f f e e t r e l a t i o n s h i p t h a t may be i n v o l v e d i n t h e t h r e e p r o c e d u r e s . But i t i s a p p a r e n t t h a t from q u i t e d i f f e r e n t i n i t i a l v i e w p o i n t s ( " b i o c o e n o s i s " v e r s u s " b i o t o p e " ) , v e r y d i f f e r e n t ways o f t h i n k i n g ab o u t a s s o c i a t i o n s have d e v e l o p e d . B i o l o g i c a l l y D e te rm in e d A s s o c i a t i o n s ( " B i o c o e n o s e s " ) I n 1877 when M oebius was f a c e d w ith t h e n e e d f o r a te r m t o d e s i g n a t e th e a g g r e g a t i o n o f a n im a l s p e c i e s c o l l e c t e d by h i s d r e d g e fro m an o y s t e r b e d , he c o in e d th e word " b i o c e n o s e " (H e d g p e th , 1 9 5 7 a ) . Some arg u m en t e x i s t s a s t o t h e p r e c i s e m eaning o f h i s w ord, " b i o c e n o s e , " b u t i t i s g e n e r a l l y t h o u g h t t h a t he i n t e n d e d t o convey th e i d e a o f C o m m u n ity " (C le m e n ts and S h e l f o r d , 1 9 3 9 ). Today th e word i s u s u a l l y u n d e r s t o o d t o im p ly more d e m o n s t r a b l e i n t e r d e pen d en ce and i n t e r r e l a t i o n s h i p t h a t i s i n d i c a t e d by t h e more common u s a g e o f t h e word ’'co m m u n ity ” (H e d g p e th , 1 9 5 7 a ) . A c c o r d in g t o E l t o n (1 9 6 6 ) th e f i r s t c o m p re h e n s iv e i n v e s t i g a t i o n o f t h e m a rin e e c o s y s te m was C. G. J . P e t e r s e n ’ s s u rv e y o f m a rin e l i f e o f t h e D a n is h c o a s t and in l a n d s a l t f j o r d s o r " t h e L i m f j o r d s ” ( I f e t e r s e n , 1913, 1915, 1918, 1924 and P e t e r s e n and J e n s e n , 1 9 1 1 ). P e t e r s e n i s c r e d i t e d w i t h t h e a p p l i c a t i o n o f q u a n t i t a t i v e s a m p lin g t e c h n iq u e s t o t h e s t u d y o f b e n t h i c e c o l o g y ( L o n g h u r s t , 1 9 6 4 ). H is p r im a r y i n t e n t i o n was to o b t a i n a s e r i e s o f q u a n t i t a t i v e sam p les o f t h e more common l a r g e r a n im a ls o f th e s e a b o tto m t o s e r v e a s th e b a s i s f o r a n e s t i m a t i o n o f t h e q u a n t i t y o f f i s h f o o d a v a i l a b l e f o r p l a i c e and o t h e r d e m e r s a l f i s h ; i n i t i a l l y he had no i n t e n t i o n o f d e s c r i b i n g a n im a l a s s o c i a t i o n s ( T h o r s o n , 1 9 5 7 ). A f t e r s e v e r a l y e a r s o f i n v e s t i g a t i o n P e t e r s e n o b s e rv e d t h a t r e a s o n a b l y u n if o r m c o m b i n a t i o n s o f b e n t h i c m a c r o - i n v e r t e b r a t e s p e c i e s , w i t h a few c o n s p ic u o u s s p e c i e s , i n h a b i t e d l a r g e d i s c r e t e r e g i o n s o f h i s s u r v e y a r e a . E ach o f t h e s e was c h a r a c t e r i z e d by a few n u m e r i c a l l y a b u n d a n t f o rm s ; P e t e r s e n named h i s a s s o c i a t i o n s a f t e r su ch a n im a ls . From i t s i n c e p t i o n much o f q u a n t i t a t i v e b e n t h i c e c o lo g y h a s i n v o l v e d t h e d e s c r i p t i o n o f a n im a l a s s o c i a t i o n s named f o r a few " d o m in a n t" o r g a n i s m s . 8 S h e l f o r d (1 9 3 5 , p . 326) r e g a r d s P e t e r s e n ’s w o rk as n o te w o r th y i n t h r e e r e s p e c t s : F i r s t , P e t e r s e n d id n o t s t a r t o u t t o s tu d y com m u n i t i e s b u t s a y s t h e y w e re f o r c e d u p o n him by h i s r e s e a r c h e s . S e c o n d , he and h i s a s s o c i a t e s u sed a c c u r a t e q u a n t i t a t i v e m ethods t h r o u g h o u t lo n g p e r i o d s . T h i r d , t h e i r a r ra n g e m e n t o f c o m m u n itie s i s e n t i r e l y p a r a l l e l w i t h t h o s e o f th e p l a n t and a n im a l e c o l o g i s t s , who use l a r g e t e r r e s t r i a l c o m m u n itie s a s fu n d a m e n ta l u n i t s . T h o rs o n (1 9 5 7 ) s t r e s s e s t h e f a c t t h a t P e t e r s e n him s e l f r e g a r d e d th e b e n t h i c a n im a l a s s o c i a t i o n s of D a n is h w a t e r s o n ly a s d e s c r i p t i v e - s t a t i s t i c a l u n i t s , and a s su ch th e y a r e a c c e p t e d by m o st e c o l o g i s t s . T h o r s o n ( 1 9 5 5 , 1957, 1958) h a s c o n t i n u e d and ex p an d ed t h e s t u d y o f t h e s e l e v e l - b o tto m a s s o c i a t i o n s . He r e g a r d s them a s e c o l o g i c a l u n i t s ( i . e . , b i o c o e n o s e s ) composed o f c o m p a t i b l e s p e c i e s p o p u l a t i o n s fo rm in g s t a b l e a s s e m b la g e s d e t e r m i n e d m a in ly b y b i o l o g i c a l r a t h e r th a n p h y s i c a l f a c t o r s . Much o f h i s r e a s o n in g i s b a s e d on e v id e n c e g a in e d i n h i s s t u d i e s on l a r v a l e c o l o g y . He d o e s n o t c o n s i d e r s u b s t r a t e ( t h e b i o t o p e ) as an u n i m p o r t a n t f a c t o r i n d e t e r m i n i n g t h e c o m p o s itio n o f b o tto m a n im a l a s s o c i a t i o n s , b u t he p o i n t s o u t t h a t t h e b i o l o g i c a l q u a l i t i e s o f t h e s e d im e n t i n h a b i t e d by a p a r t i c u l a r a s s o c i a t i o n , c a u s e d p e r h a p s by t h e s e c r e t i o n s or e x c r e t i o n s o f t h e p a r e n t o r g a n is m s , c o u ld be t h e r e a l a t t r a c t a n t s f o r th e l a r v a l fo rm s . F u r t h e r , c i r c u m s t a n c e s f o l l o w i n g l a r v a l s e t t l i n g , su ch as p r e d a t i o n , may be f a r m ore i m p o r t a n t f a c t o r s . 9 T h o rso n p e r s u a s i v e l y cam paigns f o r t h e r e c o g n i t i o n of t h e b e n t h i c ’’com m unity” ( = a s s o c i a t i o n ) as a b i o l o g i c a l r e a l i t y . I m p o r ta n t c o r o l l a r i e s o f T h o r s o n ’ s c o n c e p t o f t h e b e n t h i c "com m unity” a s an e c o l o g i c a l u n i t (o r " b i o c o e n o s i s " ) a re t h e f o l l o w i n g : ( 1 ) " t h e l e v e l b o tto m a r e a s o f th e s e a a re among th e m ost u n ifo r m f l a t s on o ur g lo b e . . ( p . 3 8 7 ), (2 ) " . . . th e e c o l o g i c a l c o n d i t i o n s p r e v a i l i n g i n m a rin e l e v e l - b o t t o m c o m m u n itie s a re s im p le and w e l l s u i t e d f o r r e s e a r c h " ( p . 3 9 4 ) , and ( 3 ) " . . . th e same ty p e s o f l e v e l b o tto m s u b s t r a t a a t s i m i l a r d e p t h s a re q u a n t i t a t i v e l y d o m in a te d by i n v e r t e b r a t e s b e lo n g in g t o th e same g e n e r a b u t to d i f f e r e n t s p e c i e s " ( p . 387, T h o rs o n , 1 9 5 5 ). T h o rso n (1 9 5 5 , pp. 387-388) i l l u s t r a t e s th e c o n c e p t of " p a r a l l e l l e v e l - b o t t o m c o m m u n itie s" (= e c o l o g i c a l l y e q u i v a l e n t a s s o c i a t i o n s ) as f o l l o w s : D i f f e r e n t c o m m u n itie s , alw ays i n c l u d i n g s p e c i e s o f th e l a m e l l i b r a n c h g e n e r a Macoma, C ardium and Mya a s d o m in a n ts and alw ays a s s o c i a t e d w ith m ixed b o t tom s j u s t below t h e t i d a l z o n e , a r e known fro m h ig h - a r c t i c a s w e l l a s b o r e a l - a t l a n t i c s e a s , fro m th e P a c i f i c c o a s t o f t h e U n ite d S t a t e s , from J a p a n , from E a s t A f r i c a , and so on, t h u s m aking a c h a in o f " p a r a l l e l " Macoma c o m m u n ities t h a t r e p l a c e e a c h o t h e r i n a c c o r d a n c e w ith l a t i t u d e and t e m p e r a t u r e . C h a in s o f p a r a l l e l Venus c o m m u n itie s , alw ay s a s s o c i a t e d w ith sandy b o tto m s i n s h a llo w w a te r and dom i n a t e d by t h e l a m e l l i b r a n c h g e n e r a Venus and S p i s u l a o r M a c tr a , a re known fro m E a s t G r e e n la n d , th e N o rth S e a , th e M e d it e r r a n e a n , and th e P e r s i a n G u l f . C h a in s o f p a r a l l e l c o m m u n ities o f b r i t t l e s t a r s , a s s o c i a t e d w ith muddy b o tto m s i n somewhat d e e p e r w a t e r and d o m in a te d by r e p l a c i n g s p e c i e s o f th e g e n e r a A m p h iu ra , A m p h io d ia , and A m p h io p lu s , a r e known fro m th e N o r th A t l a n t i c , th e B la c k S e a , th e P e r s i a n G u l f , J a p a n , New Z e a la n d , t h e c o a s t o f C h i l e , and th e V ancouver r e g i o n . 10 H av in g h e r e g iv e n e x a m p le s fro m s a n d y , m ix ed , and muddy b o t t o m s , we f i n d t h a t e a c h s e r i e s o f p a r a l l e l c o m m u n itie s shows u n if o r m f e a t u r e s q u a l i t a t i v e l y a s w e l l a s q u a n t i t a t i v e l y e v e r y w h e r e . ( p p . 3 8 7 -3 8 8 ) F or an e x t e n s i v e r e v i e w o f l e v e l b o tto m a s s o c i a t i o n s o f th e w o r ld s e e T h o rso n ( 1 9 5 7 ) . The e x t e n s i v e i n v e s t i g a t i o n o f t h e m a rin e a s s o c i a t i o n s of P u g e t Sound by th e p i o n e e r t e r r e s t r i a l e c o l o g i s t V. E. S h e l f o r d and h i s a s s o c i a t e s ( S h e l f o r d and T o w le r, 1925; Weese and MacNab, 1930; W eese, 1933; S h e l f o r d , W eese, R ic e , R asm ussen and M acLean, 1935; and sum m arized i n C le m e n ts and S h e l f o r d , 1939) f u r n i s h e s an a d d i t i o n a l exam p l e o f t h e c o n c e p t t h a t b e n t h i c T T c o m m u n itie s M (= a s s o c i a t i o n s ) a r e e c o l o g i c a l u n i t s o r " b i o c o e n o s e s . " S h e l f o r d and T o w ler ( 1 9 2 5 , p. 4 3) comment t h a t ’’t h e c o n t r o v e r s y a s t o w h e th e r a g g r e g a t i o n s o f o rg a n is m s o r h a b i t a t s , i . e . , t h e o b v io u s c o n d i t i o n s , s h o u ld be u se d a s a b a s i s f o r communi t i e s i s an o u tg ro w th o f a l a c k o f kno w led g e o f communi t i e s . ” R e g a rd in g th e aim o f t h e i r w ork th e y s t a t e ( p . 44) t h a t ’’th e p r e s e n t p a p e r i s an a t t e m p t t o a r r a n g e th e m a rin e c o m m u n itie s a lo n g l i n e s b a s e d on a g g r e g a t i o n s r a t h e r t h a n h a b i t a t . ” Of t h e i r c o n c l u s i o n s th e f o l l o w i n g s h o u ld b e n o te d ( p . 6 9 ) : ( 1 . ) C om m unities m ust be d e t e r m in e d b y dom i n a n t s r a t h e r t h a n h a b i t a t ; th e l i m i t s o f t h e do m i n a n t s a s such a r e t h e l i m i t s o f th e com m unity. ( 4 . ) D om inant o rg a n is m s b e s t i l l u s t r a t e th e p h y s i o l o g i c a l c h a r a c t e r s o f th e com m unity and a r e t h e b e s t i n d i c a t o r s of th e com m unity. 11 ( 5 . ) S e c o n d a ry s p e c i e s and uncommon s p e c i e s a re o f m in o r s i g n i f i c a n c e i n e c o lo g y ( th o u g h th e c h i e f i n t e r e s t o f taxonom y and ta x o n o m ic s u r v e y s ) . ( 8 . ) S u c c e s s io n t a k e s p la c e v e r y r a p i d l y i n th e s e a , a c lim a x p r o b a b ly b e i n g r e a c h e d on h a rd b o tto m s i n a y e a r o r tw o . S u c c e s s io n i s much l e s s r a p i d on s o f t e r b o tto m s . The e s t a b l i s h m e n t o f a h a rd b o tto m community on c o m p a r a t i v e l y s o f t b o tto m m ust a w a it th e a c c u m u la tio n o f s h e l l s . On th e b a s i s o f t h e i r q u a n t i t a t i v e i n v e s t i g a t i o n ( P e t e r s e n g r a b ) S h e l f o r d and T o w ler (1 9 2 5 ) d e s c r i b e t h r e e m ajo r " b i o t i c f o r m a t i o n s or b io m e s" ( e q u i v a l e n t to b i o c o - e n o s e s ) . Each o f t h e s e i s s u b d iv i d e d i n t o s m a l l e r u n i t s term ed " a s s o c i a t i o n s " ; th e " a s s o c i a t i o n s " a re f u r t h e r s u b d i v i d e d i n t o " f a c i a t i o n s ." A nim al s p e c i e s i m p o r t a n t to th e d e f i n i t i o n o f t h e s e f a u n a l u n i t s are v a r i o u s l y term e d " d o m i n a n t s ," " p r e v a l e n t s ," " p r e d o m i n a n t s ," " i n f l u e n t s " and " c h a r a c t e r i s t i c s p e c i e s . " L o n g h u rs t (T 964) h a s n o te d t h a t r i g i d h i e r a r c h i c a l s y ste m s o f c l a s s i f i c a t i o n su c h a s t h a t em ployed by S h e l f o r d and h i s a s s o c i a t e s have g a in e d l i t t l e g e n e r a l a c c e p t a n c e . R e a s o n a b le d o u b t h a s b een r a i s e d as t o th e p r o p r i e t y o f a p p l y i n g t h e c o n c e p ts o f c lim a x and s u c c e s s i o n , f o r m u l a t e d on th e b a s i s o f t e r r e s t r i a l r e s e a r c h , t o th e m a rin e e c o s y s te m . H ed g p eth (1 9 5 7 a ) h a s commented t h a t " . . . th e s tu d y o f c o m m u n ities h a s b e e n p r i n c i p a l l y i n th e h an d s o f t e r r e s t r i a l b o t a n i s t s and e c o l o g i s t s , and some o f th e c o n c e p ts d e v e lo p e d f o r t e r r e s t r i a l s i t u a t i o n s a r e n o t g e n e r a l l y a p p l i c a b l e t o th e s e a . " 12 E n v i r o n m e n t a l l y D e te rm in e d A s s o c i a t i o n s ( " B i o t o p e s " ) The i d e a s o f L i n d r o t h (1 9 3 5 ; t r a n s . 1962) c o n c e r n in g t h e d e t e r m i n a t i o n and c o n s t i t u t i o n o f m a rin e b e n t h i c a s s o c i a t i o n s c o n f l i c t w i t h t h o s e o f P e t e r s e n , T h o rso n and S h e l f o r d . L i n d r o t h s im p ly d o e s n o t t h i n k t h a t su c h a s s o c i a t i o n s e x i s t i n th e s e a . He b a s e s h i s c o n c l u s i o n s on h i s w ork i n t h e G u llm a r f j o r d and on h i s c a r e f u l r e - e x a m i n a t i o n o f t h e d a t a o f P e t e r s e n , M o lan d e r (who a l s o w orked on th e G u llm a r f j o r d ) and o t h e r s . L i n d r o t h i d e n t i f i e s t h e f r a c t i o n o f t h e b e n t h i c o r g a n ism s w ith w h ic h he d e a l t a s th e e n t i r e " b i o c o e n o s i s , a p a r t from t h e m i c r o f a u n a and m i c r o f l o r a " ; s i n c e t h e r e was " a b s o l u t e l y " no m a c r o f l o r a i n h i s s t u d y a r e a , t h e s e a s se m b l a g e s c o n s t i t u t e z o o c o e n o s e s , a n im a l s p e c i e s o n l y . He d e s c r i b e s t h e e n v iro n m e n t a s f o l l o w s : " . . . I do n o t t h i n k I am g u i l t y o f d i s t o r t i o n o f th e f a c t s when I s t a t e t h a t n e i t h e r th e h y d r o g r a p h i c m i l i e u n o r t h e ty p e o f b o tto m shows d e f i n i t e b r e a k s i n c o n t i n u i t y . " ( p . 3) W hereas P e t e r s e n d i d n o t s e e k a s s o c i a t i o n s b u t fo u n d them , L i n d r o t h e x p e c t e d them and d i s c o v e r e d n o n e. The l a t t e r c o n c l u d e s t h a t . . . t h e a n im a l s p e c i e s ( g e n e r a l l y o n ly a n im a ls a r e b e in g d e a l t w i t h ) o f s o f t s e a - f l o o r s have t h e i r d i s t r i b u t i o n d e t e r m in e d on t h e w hole d i r e c t l y b y th e " e x t e r n a l e n v i r o n m e n t , " and d i r e c t c h e m ic a l and p h y s i c a l f a c t o r s . B i o t i c f a c t o r s a r e o f s e c o n d a r y im p o r ta n c e a s th e y l i n k " f o r m s - o f - l i f e " u n i t s and t h e s e u n i t s a r e r e p r e s e n t e d by s e v e r a l s p e c i e s even 13 w i t h i n r e l a t i v e l y s m a ll a r e a s . B e l i e f i n n a t u r a l l y d e m a r c a te d v e g e t a t i o n u n i t s (c o m m u n itie s ) w i t h a v e g e t a t i o n ( f a u n a ) I s i c ] o f t h i s k i n d i s a p i e c e o f p u re m y s t i c i s m . ( p . 15) A c o m p re h e n s iv e re v ie w o f q u a n t i t a t i v e b e n t h i c ma r i n e e c o l o g y i s p r o v i d e d by N. S. J o n e s ( 1 9 5 0 ) . He r e j e c t s d i s c o n t i n u i t i e s b e tw e e n " c o m m u n itie s " (= a s s o c i a t i o n s ) b ased on c h a r a c t e r i s t i c a n i m a l s a s b e i n g s u b j e c t i v e and i n a d e q u a te a s th e b a s i s o f a c l a s s i f i c a t o r y s y s te m . I n s t e a d he p r o v i d e s a s y s te m b a s e d on e n v ir o n m e n ta l f a c t o r s . T e m p e ra tu re i s th e c r i t e r i o n u s e d t o s e p a r a t e th e m a jo r s u b d i v i s i o n s or " r e g i o n s . " Each r e g i o n i s d i v i d e d on t h e b a s i s o f t o p o g r a p h y , d e p t h , and s a l i n i t y i n t o a gro u p o f " c o m m u n itie s " such a s " o f f s h o r e c o m m u n itie s ." Each o f t h e s e g ro u p s o f "com m u n i t i e s " i s d i v i d e d i n t o two s u b - g r o u p s , " b i o m e s ," on th e g e n e r a l q u a l i t y ( h a r d v e r s u s s o f t b o tto m s ) o f th e s u b s t r a t e . The biom es may be f u r t h e r s u b d iv i d e d i n t o more s p e c i f i c s u b s t r a t e c a t e g o r i e s , " a s s o c i a t i o n s , " su ch a s "muddy s a n d ." The d e s i g n a t i o n o f a f a u n a l u n i t by t h i s s y ste m c o u ld be r a t h e r cum bersom e, e . g . , " t h e mud a s s o c i a t i o n o f th e A t l a n t i c b o r e a l o f f s h o r e s o f t - b o t t o m b io m e ." The a s s o c i a t i o n s d e s c r i b e d by o t h e r w o r k e r s , p a r t i c u l a r l y P e t e r s e n , w e re r e c l a s s i f i e d b y J o n e s a c c o r d i n g t o t h i s e n v i r o n m e n t a l l y b a s e d s y s te m . Thus P e t e r s e n ’ s "Macoma b a l t i c a com m unity" becom es " t h e A t l a n t i c b o r e a l s h a llo w mud a s s o c i a t i o n . " In some i n s t a n c e s t h i s r e c l a s s i f i c a t i o n r e s u l t e d i n t h e combin a t i o n o f s e v e r a l a s s o c i a t i o n s d e te r m in e d by th e more 14 c l a s s i c a l a p p ro a c h o f "com m unity” d e s i g n a t i o n b ased on f a u n a l c o m p o s itio n and i d e n t i f i e d on the b a s i s o f " d o m in a n t" o r g a n is m s . N. S. J o n e s (1 9 5 0 , p. 295) s t a t e s t h a t " . . . t h e r e i s v e r y l i t t l e ground f o r b e l i e v i n g t h a t any l a r g e a n im a l a sse m b la g e o f a n im a l s p e c i e s r e a c t s as a u n i t or i s bound t o g e t h e r by p u r e l y b i o l o g i c a l f a c t o r s . " He comments f u r t h e r (p . 2 9 5 ) , " . . . The d i v i s i o n i n t o c o m m u n ities i s l a r g e l y s t a t i s t i c a l " and . . t h e r e i s no p ro n o u n ced d i s c o n t i n u i t y b e tw e e n a d j a c e n t c o m m u n ities . . . " F i n a l l y he c o n c lu d e s by s t a t i n g ( p . 3 1 0 ), I t i s c o n c lu d e d t h a t w h ile t h e r e h a s b een much d is a g r e e m e n t a b o u t t h e c o n s t i t u t i o n o f t h e communi t i e s , th e c h i e f c r i t i c i s m has b een d i r e c t e d a g a i n s t t h e view t h a t th e y a r e u n i t s bound t o g e t h e r by b i o l o g i c a l f a c t o r s . T h e re i s l i t t l e e v id e n c e f o r t h i s i d e a . H ow ever, m ost w o rk e rs a g r e e t h a t c o m m u n ities e x i s t and t h a t t h e r e i s a c o r r e l a t i o n b e tw e e n t h e i r d i s t r i b u t i o n and t h a t o f c e r t a i n p h y s i c a l f a c t o r s . The i n a b i l i t y t o d i s c o v e r d i s c r e t e a s s o c i a t i o n s o f o rg a n ism s i n t h e m a rin e e n v iro n m e n t and th e g e n e r a l t h e s i s t h a t e n v iro n m e n t i s t h e prim e d e t e r m in e r o f s p e c i e s d i s t r i b u t i o n a re s u g g e s te d b y th e i n v e s t i g a t i o n s made by two C a l i f o r n i a m a r in e e c o l o g i s t s . On t h e b a s i s o f an i n t e n s i v e q u a n t i t a t i v e sa m p lin g pro g ram in San Pedro Bay ( th e r e g i o n b e tw e e n th e m a in la n d and S a n ta C a t a l i n a I s l a n d ) Hartm an (1 9 5 5 ; 1966) d e s c r i b e s t h e fa u n a o f th e r e g i o n as e x h i b i t i n g " a p a t c h i n e s s o f o c c u r r e n c e w h ich i s u n p r e d i c t a b l e and a t p r e s e n t u n e x p l a i n a b l e . " T h is ty p e o f d i s t r i b u t i o n h a s been 15 te rm e d " r e t i c u l a t e d " by H ed g p eth ( 1 9 5 7 a , p . 4 6 ) ; he s u g g e s t s t h a t i n such a r e a s " . . . c o n d i t i o n s may be su c h t h a t l i t t l e u n i f o r m i t y can be a t t a i n e d b y th e o r g a n i s m s , and t h e t r a d i t i o n a l v ie w o f a r e l a t i v e l y u n ifo r m b o tto m com m unity d o m i n a t e d by a c o m p a r a t i v e l y s m a l l number o f c o n s p ic u o u s s p e c i e s m ust be aban d o n ed . . . " R e p o r t i n g on e i g h t y e a r s o f s t u d y o f a l i t t o r a l ma r i n e m u d - f l a t ( E lk h o r n S lo u g h , C a l i f o r n i a ) , M a c G in itie (1 9 3 5 ) a p o l o g i z e s f o r h i s i n a b i l i t y t o d e s i g n a t e a s s o c i a t i o n s . He makes th e f o l l o w i n g q u a l i f i c a t i o n ( p . 6 5 3 ) : I t seems to be t h e g e n e r a l p r o c e d u r e i n e c o l o g i c a l i n v e s t i g a t i o n s to l i s t th e s p e c i e s o f o rg a n ism s u n d e r a s s o c i a t i o n s and z o n e s . So s t r o n g h a s b e e n t h i s cu sto m t h a t I am q u i t e s u r e i t h a s b e e n v e r y d e c i d e d l y o v e rw o rk e d . I n th e f i r s t p l a c e I b e l i e v e t h a t i t h a s c a r r i e d o v e r fro m p l a n t e c o l o g y , w h ic h was th e o r i g i n a l e c o l o g y ; and w h i l e i t may work v e r y w e l l f o r a f i x e d f l o r a l r e g i o n , t h i s c u sto m s h o u ld be u s e d i n a n im a l s t u d i e s w i t h a g r e a t d e a l o f c i r c u m s p e c tio n . I t h i n k t h a t i n i n v e s t i g a t i o n s c a r r i e d on o v e r a lo n g p e r i o d o f tim e one becom es l e s s and l e s s s u r e j u s t how much v a l u e s u c h c o m p i l a t i o n o f th e m a rin e a n i m a l s a c c o r d i n g t o a s s o c i a t i o n s and z o n in g may h a v e . H ence, i n t h i s p a p e r l i t t l e a t te m p t a t a s s o c i a t i o n or z o n a l l i s t s h a s b e e n m ade. However, th e f o l l o w i n g d i s c u s s i o n i s o f su c h im p o r t a n c e t h a t t h e o m is s io n o f su c h l i s t s s h o u ld i n no way d e t r a c t fro m th e v a l u e o f t h e p a p e r . C o m b in a tio n A p p ro a c h e s ( " B i o c o e n o s i s and B i o t o p e " ) I n r e c e n t e f f o r t s d i r e c t e d a t t h e p ro b le m o f c l a s s i f y i n g m a rin e b e n t h i c a s s o c i a t i o n s , i n v e s t i g a t o r s h av e em p lo y e d b o t h b i o l o g i c a l and e n v i r o n m e n ta l f a c t o r s i n t h e d e v e lo p m e n t o f s y s te m s f o r t h i s p u r p o s e . L o n g h u r s t (1 9 6 4 , 16 p . 14) s u p p o r t s t h e s e e f f o r t s , com m enting, . . . i t i s p r o b a b le t h a t n e i t h e r an e x c l u s i v e l y b io t o p e n o r an e x c l u s i v e l y b i o c o e n o s i s c l a s s i f i c a t i o n i s c o m p le te ly s a t i s f a c t o r y ; i f th e b i o t o p e p r o t a g o n i s t s a re a b l e t o a rg u e t h a t t h e b o u n d a r i e s b e tween f a u n a - b a s e d co m m u n itie s a r e i n many c a s e s s t a t i s t i c a l l y u n s a t i s f a c t o r y , th e b i o c o e n o s i s p r o t a g o n i s t s can r e p l y , w i t h e q u a l j u s t i f i c a t i o n , t h a t i t i s d i f f i c u l t o r i m p o s s i b l e t o c l a s s i f y m a rin e s e d im e n ts i n su c h a way t h a t t h e r e i s n o t a s i m i l a r d i f f i c u l t y i n d e l i n e a t i n g c a t e g o r i e s ; th e s i t u a t i o n seems t o be t h a t w h ile i t i s e s s e n t i a l t o have th e use o f a b s o l u t e d i s c o n t i n u i t i e s i n an y sy ste m o f c l a s s i f i c a t i o n , b e n t h i c c o m m u n ities a r e so o r g a n iz e d t h a t su ch d i s c o n t i n u i t i e s c a n n o t be d e m o n s t r a t e d . Any c l a s s i f i e r m ust a c c e p t t h i s f a c t and s e l e c t a sy ste m f o r i t s u t i l i t y r a t h e r th a n f o r i t s su p p o sed c o rre s p o n d e n c e w i t h r e a l i t y - - o r m ust a t l e a s t n o t o v e r s t a t e i t s r e a l i t y . Such a tw o f o ld s y ste m h a s been p ro p o s e d by P e r e s and i s a p p l i e d t o th e a s s o c i a t i o n s o f th e M e d it e r r a n e a n Sea by P e r e s and P i c a r d ( 1 9 6 4 ) . The r e c o g n i t i o n t h a t b o th b i o l o g i c a l and e n v ir o n m e n ta l f a c t o r s m e r i t c o n s i d e r a t i o n when d e a l ing w ith m a rin e b e n t h i c a s s o c i a t i o n s i s r e c o g n i z e d by P e r e s and P i c a r d (1 9 6 4 , p . 9, my t r a n s l a t i o n ) , who s t a t e , "The n o t i o n o f b i o c o e n o s i s i s i n s e p a r a b l e fro m t h a t o f b i o t o p e . " They d e f i n e b i o c o e n o s i s as . . . a g r o u p in g o f l i v i n g b e i n g s c o r r e s p o n d in g by t h e i r c o m p o s i t i o n , by t h e number o f s p e c i e s and o f i n d i v i d u a l s , t o c e r t a i n mean c o n d i t i o n s o f th e m i l i e u , a g r o u p in g o f b e i n g s w h ich a r e l i n k e d b y a r e c i p r o c a l d e p e n d e n c e and m a i n t a i n th e m s e lv e s by r e p ro d u c in g i n a f i x e d p la c e o f p e rm a n e n t f a s h i o n . The b io t o p e (= h a b i t a t ) i s " a g e o g r a p h ic a r e a , v a r i a b l e i n s u r f a c e o r volum e, s u b j e c t to c o n d i t i o n s o f w hich th e dom i n a n t a r e h o m o g en eo u s," ( P e r e s and P i c a r d , 1964, p . 9, my t r a n s l a t i o n ) . T hese a u t h o r s b e l i e v e t h a t c o n d i t i o n s 17 e x t e r n a l t o p o p u l a t i o n s f i x t h e i r l i m i t s . B i o t i c f a c t o r s , i n h e r e n t i n th e p o p u l a t i o n s th e m s e lv e s , m o d ify t h e i n t r a a s s o c i a t i o n e n v iro n m e n t and c o n t r i b u t e to t h e s t a b i l i t y o f th e a s s o c i a t i o n . T hese a u t h o r s c o n te n d t h a t n o n - b i o t i c f a c t o r s s e t l i m i t s on t h e d i s t r i b u t i o n o f s p e c i e s . W ith in t h e s e l i m i t s b i o t i c f a c t o r s , w hich i n c l u d e th e i n t e r a c t i o n o f p o p u l a t i o n s w ith t h e e n v iro n m e n t as w e l l as w i t h e a c h o t h e r , d e te r m in e th e c h a r a c t e r i s t i c s o f th e “b i o c o e n o s i s . M B ecause t h e r e a r e no s h a r p d i s t i n c t i o n s b e tw e e n a d j a c e n t " b i o t o p e s , '' a zone o f t r a n s i t i o n i n w h ich m ixed c h a r a c t e r i s t i c s a r e p r e s e n t i s t y p i c a l . I t s m a g n itu d e i s d e te r m in e d by th e s h a r p n e s s o f th e g r a d i e n t d e s c r i b i n g th e ch a n g in g f a c t o r s . I n th e P e r e s sy ste m of c l a s s i f i c a t i o n th e m ajo r s u b d i v i s i o n s a r e b ro a d h o r i z o n s d e l i m i t e d by d e p t h ; e a c h o f t h e s e i s s e c o n d a r i l y d i v i d e d i n t o s m a l l e r u n i t s , th e " b i o t o p e s . " W ith in e a c h g e n e r a l b i o t y p i c u n i t , a s s o c i a t i o n s a re d i s t i n g u i s h e d on e i t h e r a f a u n a l ( " b i o c o e n o t i c " ) or an e n v i r o n m e n t a l ( " b i o t o p i c " ) b a s i s ( L o n g h u r s t , 1964; P e r e s and P i c a r d , 1 9 6 4 ). Pager (1 9 6 3 , p . 416) h a s commented on th e d e g re e t o w hich p h y s i c a l and b i o l o g i c a l f a c t o r s a r e i m p o r t a n t a s d e t e r m i n e r s o f f a u n a l c o m p o s itio n . The r e l a t i v e Im p o rta n c e o f th e p h y s i c a l and b i o l o g i c a l a s p e c t s o f th e e n v iro n m e n t c h a n g e s from p l a c e to p l a c e , th e b i o l o g i c a l g e n e r a l l y becom ing more i m p o r t a n t a s th e p h y s i c a l becom es l e s s v a r ia b le , b u t n e i t h e r i s e v e r e n t i r e l y i n e f f e c t i v e . "When 18 s tu d y i n g a s s e m b la g e s i n n a t u r e i t i s n e c e s s a r y , t h e n , to c o n c e iv e o f a com plex n e tw o rk o f a c t i o n - r e a c t i o n i n v o l v i n g b o t h p h y s i c a l and b i o l o g i c a l f a c t o r s , and d e f i n e d by a s e t o f c o - o r d i n a t e s i n tim e and s p a c e . I t w i l l seldom , i f e v e r , hap p en t h a t su ch a n e tw o rk w i l l have s h a r p and im p a s s a b le l i m i t s b u t i t w i l l o f t e n be fo u n d t h a t t h e r e a r e b r o a d a r e a s o f c o n s i d e r a b l e i n t e r n a l s i m i l a r i t y b o r d e r e d by r e l a t i v e l y n a r ro w e r r e g i o n s o f r a p i d c h a n g e , t h e s e i n t u r n g r a d in g i n t o o t h e r a r e a s w i t h i n t e r n a l c o n s i s t e n c y . No one o f t h e s e i n t e r n a l l y s i m i l a r a r e a s w i l l be e x a c t l y l i k e a n o th e r b u t i f e a c h must be t r e a t e d a s an u n iq u e i n d i v i d u a l , g e n e r a l i z a t i o n w i l l be d i f f i c u l t . One n e e d s , t h e r e f o r e , to d e c id e how o f t e n and how p r e c i s e l y an a s se m b la g e m ust be r e p e a t e d i n s p a c e b e f o r e i t can be c o n s i d e r e d a g e n e r a l enough phenomenon to m e r i t c a r e f u l s t u d y i n t h e hope o f d i s c o v e r i n g some w id e ly a p p l i c a b le p r i n c i p l e s . T h is d e c i s i o n u l t i m a t e l y r e s t s on e x p e r i e n c e and i n t u i t i o n , b u t t h e r e a r e some o b j e c t i v e ways o f i d e n t i f y i n g , d e s c r i b i n g 'a n d co m p arin g a s s e m b la g e s w hich w i l l h e l p . A n o th e r a p p ro a c h t o th e t a s k o f d e f i n i n g f a u n a l g r o u p in g s i n th e s e a h a s b e e n u se d by S a v ilo v (1 9 5 7 ; a l s o s e e Z e n k e v i tc h , 1963) i n h i s s tu d y o f th e O khotsk Sea b e n t h o s . He r e s o l v e s th e d i v e r s e f a u n a o f t h i s r e g i o n i n t o " a d a p t i v e t y p e s " o r " l i f e f o r m s ," p a r t i c u l a r l y f e e d i n g types, and on th e b a s i s o f t h e s e i s a b le t o s e p a r a t e th e f a u n a of th e O k h o tsk Sea i n t o se v e n b i o l o g i c a l z o n e s ( i . e . , " t h e zone o f p re d o m in a n t d e v e lo p m e n t o f d e p o s i t - s w a l l o w i n g f o r m s " ) . T hese zo n e s a re v e r t i c a l l y d i s t r i b u t e d ( S a v i l o v , 1957, f i g u r e 10, p . 1 3 4 ), and i n a d d i t i o n a r e r e l a t e d t o the g e n e r a l h y d r o g r a p h ic c o n d i t i o n s and s u b s t r a t e c o m p o s itio n o f t h i s m a rin e r e g i o n . P h e lp s (1 9 6 4 ) h as a l s o o b s e rv e d t h a t t h e i n t e r a c t i o n s b e tw e e n t h e p h y s i c a l e n v iro n m e n t and " l i f e fo rm s" ( f e e d i n g , b r e e d i n g and p u rc h a s e t y p e s ) a r e 19 v e r y i m p o r t a n t i n d e t e r m i n i n g f a u n a l d i s t r i b u t i o n s . S a n d e rs (1 9 5 8 ) h a s i n d i c a t e d a r e l a t i o n s h i p e x i s t s b e tw e e n s e d im e n t t y p e and t h e d i s t r i b u t i o n o f f e e d i n g t y p e s i n B u z z a rd s Bay, M a s s a c h u s e t t s . S t a t i s t i c a l D e s i g n a t i o n o f A s s o c i a t i o n s R e c e n t l y s e v e r a l a t t e m p t s h av e b e e n made t o d e f i n e , i d e n t i f y a n d c l a s s i f y f a u n a l g r o u p in g s by c o m p l e t e l y o b j e c t i v e c r i t e r i a . T h e se e f f o r t s have i n v o l v e d th e a p p l i c a t i o n o f r a t h e r com plex s t a t i s t i c a l t e c h n i q u e s ( F a g e r , 1963; Long- h u r s t , 1 9 6 4 ; P h e l p s , 1 9 6 4 ). F a g e r (1 9 5 7 ) h as d e v e lo p e d a sy ste m f o r th e d e t e r m i n a t i o n and a n a l y s i s o f r e c u r r e n t g r o u p s b a s e d on th e c o o c c u r r e n c e s o f s p e c i e s w i t h i n a sam p le s e t . A p p l i c a t i o n o f t h i s m ethod i s p r e d i c a t e d on th e r a t i o n a l e t h a t s p e c i e s w hich a r e f r e q u e n t l y p a r t o f e a c h o t h e r ' s e n v ir o n m e n t, e . g . , 50 p er c e n t of t h e ti m e , c o n s t i t u t e a p p r o p r i a t e e c o l o g i c a l u n i t s . T h i s m ethod h a s b e e n used t o d i s t i n g u i s h e d z o o p la n k - t o n s p e c i e s g ro u p s i n th e N o r th P a c i f i c Ocean (F a g e r and McGowan, 1963) and i s b e in g a p p l i e d t o s a m p le s c o l l e c t e d d u r in g a l e n g t h y s t u d y o f t h e s h a l l o w s u b l i t t o r a l b e n t h o s o f f La J o l l a , C a l i f o r n i a ( F a g e r , p e r s . com m .). F a g e r Ts i d e a s c o n c e r n in g "co m m u n ity " a r e i n t e r e s t i n g . He s t a t e s ( 1 9 6 3 , p. 4 1 5 ) t h a t he b e l i e v e s i n communi t i e s " i n t h e s e n s e o f r e c u r r e n t o r g a n i z e d s y s te m s o f o r g a n ism s w i t h s i m i l a r s t r u c t u r e i n te r m s o f s p e c i e s p r e s e n c e 20 and a b u n d a n c e , and t h a t i t i s p o s s i b l e and m e a n in g f u l t o i d e n t i f y and s t u d y th em , alw ay s w i t h th e f a c t f i r m l y i n mind t h a t t h e y a r e open s y s t e m s . ” A "com m unity" i s t h u s d e f i n e d a s a g ro u p o f s p e c i e s t h a t a r e o f t e n fo u n d l i v i n g t o g e t h e r . T h i s " o p e r a t i o n a l d e f i n i t i o n ” c a n n o t be u s e d t o d e f i n e t h e m a rin e b i o t i c com m unity b u t can be a p p l i e d t o d e f i n e a s s o c i a t i o n s . A n o th e r exam ple o f th e s t a t i s t i c a l a p p r o a c h t o th e d e f i n i t i o n o f b e n t h i c m a rin e a s s o c i a t i o n s i s p r o v id e d by P h e l p s ( 1 9 6 4 ) , who a p p l i e d th e d i v e r s i t y in d e x b a s e d on th e i n f o r m a t i o n t h e o r y a s t h e means o f d e f i n i n g an a n im a l a s s o c i a t i o n i n a New E n g la n d s a l t p o n d . I n d i c e s w ere d e te r m in e d f o r e a c h sam p le a t e a c h p o i n t i n tim e a s a m easu re o f a s s o c i a t i o n s t r u c t u r e and o r g a n i z a t i o n . R e l a t i o n s h i p s b e tw e e n th e " i n f o r m a t i o n " c a r r i e d per i n d i v i d u a l and t h e r e d u n d a n t n a t u r e o f d i s t r i b u t i o n s were u s e d to d e m o n s t r a t e t h e e x i s t e n ce o f a s s o c i a t i o n s t r u c t u r e i n san d y s e d im e n t s and i t s a b s e n c e i n mud. D i v e r s i t y v a l u e s from t h e sa n d y s e d im e n t s p r o g r e s s more sm o o th ly from one p o i n t i n tim e t o t h e n e x t . M easu rem en ts o f d i v e r s i t y from t h e muddy a r e a s o f th e pond p r o g r e s s e r r a t i c a l l y o v e r tim e . T h is m ethod i s s u p p o se d t o p r o v i d e a h i g h d e g r e e o f o b j e c t i v i t y i n d i s t i n g u i s h i n g a s s o c i a t i o n s . I t i s e v i d e n t from t h i s b r i e f r e v i e w t h a t b e n t h i c a s s o c i a t i o n s , r e g a r d e d as r e a l i t i e s by m o st b i o l o g i s t s s t u d y i n g t h e b e n t h o s , become th e s u b j e c t o f c o n t r o v e r s y 21 when t h e s p e c i f i c p r o b le m s o f t h e i r d e f i n i t i o n , i d e n t i f i c a t i o n and c l a s s i f i c a t i o n a r e e x a m in e d . T h e re i s d i s a g r e e m e n t r e g a r d i n g t h e m ost r e l i a b l e and u s e f u l a p p r o a c h t o t h e i r d e s c r i p t i o n . T h is d i s a g r e e m e n t d e r i v e s fro m th e u s e o f d i f f e r e n t m e th o d s o f e s t i m a t i n g th e r e l a t i v e i m p o r t a n c e o f t h e f a c t o r s d e t e r m i n i n g t h e c o n s t i t u t i o n and e x t e n t o f a s s o c i a t i o n s . The P u r p o s e o f t h i s I n v e s t i g a t i o n The p r e s e n t r e s e a r c h i s d i r e c t e d to w a rd c l a r i f i c a t i o n o f t h e n a t u r e o f b e n t h i c a s s o c i a t i o n s . I t i s b a s e d on d a t a fro m an e x t e n s i v e s u r v e y o f t h e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f c o n d u c te d fro m 1956 t o 1 961. T h a t s u r v e y y i e l d e d d e s c r i p t i o n s o f a num ber o f m a c r o f a u n a l a s s o c i a t i o n s . The p r e s e n t i n v e s t i g a t i o n a p p l i e s c o m p u te r p r o grammed s t a t i s t i c a l g r o u p in g t e c h n i q u e s t o t h e d a t a r e s u l t in g fro m t h a t s u r v e y , w i t h t h e p r i n c i p a l o b j e c t i v e o f i d e n t i f y i n g s p e c i e s g r o u p s . T h e s e g r o u p s a r e com pared w i t h t h e a s s o c i a t i o n s d e f i n e d d u r i n g t h e p r e v i o u s s t u d y o f t h e s h e l f , i n an e f f o r t t o e x p l o r e a l t e r n a t i v e m e th o d s f o r t h e r e c o g n i t i o n o f b e n t h i c m a c r o f a u n a l a s s o c i a t i o n s . S u b s i d i a r y o b j e c t i v e s a r e : 1. t o d e t e r m i n e th e i d e n t i t y o f t h e p r i n c i p a l m a c r o f a u n a l i n v e r t e b r a t e s p e c i e s o f t h e m a in la n d s h e l f u s i n g q u a n t i t a t i v e t e c h n i q u e s ; 2 . t o ex am in e t h e d i s t r i b u t i o n o f t h i s 22 i m p o r t a n t f a u n a l f r a c t i o n o v er th e r a n g e o f e a c h o f s e v e r a l p h y s i c a l v a r i a b l e s and w i t h i n th e p r e v i o u s l y d e f i n e d a s s o c i a t i o n s ; 3- t o d e t e r m in e t h e e x t e n t t o w hich s p e c i e s c o n fo rm t o th e d i s t r i b u t i o n s o f a s s o c i a t i o n s o f w h ic h th e y h av e b e e n c o n s i d e r e d i m p o r t a n t e l e m e n t s ; 4 . t o p r o v i d e a c o m p re h e n siv e r e v ie w and r e e x a m i n a t i o n o f th e i n f o r m a t i o n a b o u t th e b e n t h i c m a c ro fa u n a o f th e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f b a s e d on p u b l i s h e d , parapublished"*" and u n p u b l i s h e d s o u r c e s . T h is r e v iew , w h ic h p r o v i d e s t h e c o n t e x t f o r t h e d i s c u s s i o n o f th e r e s u l t s o f t h e p r e s e n t s t u d y , i s c o n t a i n e d i n an e x t e n s i v e a p p e n d ix t o t h i s r e p o r t . The r e s u l t s o f t h e p r e s e n t i n v e s t i g a t i o n a r e e x am ined i n r e l a t i o n s h i p t o th e p r e v a l e n t c o n c e p ts t h a t a r e a p p l i e d t o b e n t h i c m a rin e m a c r o f a u n a l a s s o c i a t i o n s , a s d i s c u s se d i n th e i n t r o d u c t i o n . The S tu d y A re a A c h a r a c t e r i z a t i o n o f i t s e n v ir o n m e n t i s b a s i c t o t h e s tu d y o f t h e f a u n a o f any r e g i o n . The s h e l f s e d im e n ts i T h i s te rm i s i n t r o d u c e d to d e s c r i b e s p e c i a l r e p o r t s w h ich a r e r e p r o d u c e d by m im eo g rap h , m u l t i l i t h o r o t h e r n o n - p r i n t i n g t e c h n i q u e s and d i s t r i b u t e d i n l i m i t e d and u n p u b l i c i z e d e d i t i o n s . B ec au se s u c h r e p o r t s h av e c o n s i d e r a b l e b e a r i n g on t h i s s t u d y , an i n c l u s i v e d e s c r i p t i o n o f t h e fo rm i n w h ich t h e y a r e a v a i l a b l e seems d e s i r a b l e . 23 and th e o v e r l y i n g w a te r m ass fo rm th e im m ed iate p h y s i c a l e n v iro n m e n t o f th e m a c ro fa u n a o f t h e s o u t h e r n C a l i f o r n i a m a in la n d s h e l f . B ut th e s h e l f i s o n ly a s m a l l p a r t o f a much l a r g e r m a rin e r e g i o n ; a c c o r d i n g l y , th e p r o p e r d e s c r i p t i o n o f t h e s h e l f m ust i n c l u d e t h e p e r s p e c t i v e g a in e d by lo o k in g b e yond i t s l i m i t s . The com plex o f f s h o r e a r e a o f s o u t h e r n C a l i f o r n i a i n c l u d e s i s l a n d s , b a n k s , r i d g e s , b a s i n s an d t r o u g h s and i s te rm e d a c o n t i n e n t a l b o r d e r l a n d (S h e p a rd and Em ery, 1941) ( F i g u r e 1 ) . The b o r d e r l a n d s y s te m c o n s i s t s o f b a s i n s and r i d g e s w i t h an e a s t - w e s t ( i n t h e n o r t h ) t o a n o r t h w e s t - s o u t h e a s t ( i n th e s o u t h ) o r i e n t a t i o n more or l e s s p a r a l l e l in g th e a d j a c e n t la n d t o p o g r a p h y . T o p o g r a p h ic h i g h s fo rm d e e p l y subm erged s i l l s , s h a l l o w f l a t - t o p p e d b a n k s o r i s l a n d s p r o j e c t i n g above th e s e a s u r f a c e . T h i r t e e n b a s i n s and s e v e r a l open t r o u g h s a r e e n c l o s e d by t h e s e h ig h a r e a s . Numerous su b m a rin e c an y o n s t r a n s e c t th e m a in la n d and i s l a n d s h e l v e s and some o f t h e s e d e s c e n d i n t o th e b a s i n s . The n a r row s t r i p o f ocean b o tto m im m e d ia te ly a d j a c e n t t o th e c o n t i n e n t i s d e s i g n a t e d t h e m a in la n d s h e l f ; i t makes u p o n ly 6 . 2 p e r c e n t o f t h e c o n t i n e n t a l b o r d e r l a n d (Em ery, 1 9 6 0 ) . The w i d t h o f th e m a in la n d s h e l f v a r i e s b e tw e e n 2 2 .0 k i l o m e t e r s and 0 . 8 k i l o m e t e r s . The w i d e r p o r t i o n s a re t h e S a n ta B a r b a r a s h e l f (maximum w i d t h , 1 7 .6 k i l o m e t e r s ) , t h e S a n ta M onica Bay s h e l f ( 1 8 .0 k i l o m e t e r s ) , th e San Pedro Bay s h e l f ( 2 2 .0 k i l o m e t e r s ) and t h e San D ie g o s h e l f ( 1 6 .3 Figure 1 A Map o f t h e S o u t h e r n C a l i f o r n i a n C o n t i n e n t a l B o r d e r la n d Showing th e M a in la n d S h e l f , th e O f f s h o r e B a s i n s ( c o n t o u r i n t e r v a l s i n d i c a t e b a s i n s i l l d e p t h s ; i n d i v i d u a l s o u n d in g s i n e a c h b a s i n i n d i c a t e t h e d e e p e s t p o i n t ) , t h e O f f s h o r e I s l a n d s , and th e P a t t o n E s c a r p m e n t. ( A f t e r S h e p a rd and Emery, 1 9 4 1 ). 24 25 \ VEL€ / / BASiN M _ _ _ _ 1 0 _ _ _ _ 1 0 40 _ _ _ _ 1 0 M1UTIC4L W illi (AFTER SHEPARO AND EMERY, 1941, CHART I) CONTINENTAL BORDERLAND OF SOUTHERN CALIFORNIA F i g u r e 1 26 k i l o m e t e r s ) . The s h e l f i s n a r r o w e s t a t th e h e a d s o f subm a r i n e c a n y o n s . The s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f c o m p r is e s 3639 s q u a r e k i l o m e t e r s (1 0 6 1 s q u a r e n a u t i c a l m i l e s ) o f s e a b o tto m b e tw e e n 0 and 1 8 2 .8 m e t e r s (100 f a t h o m s ) . E i g h t y - s i x p e r c e n t (3142 s q u a r e k i l o m e t e r s or 916 s q u a r e n a u t i c a l m i l e s ) o f t h i s a r e a i s s h a l l o w e r th a n 9 1 .4 m e t e r s (5 0 f a t h om s), w h ic h i s a p p r o x i m a t e l y t h e a v e r a g e d e p t h o f t h e s h e l f e d g e , b u t th e l i m i t s v a r y b e tw e e n 7 3 .2 and 1 2 8 .0 m e t e r s (40 and 70 f a th o m s ) (E m ery, 1 9 6 0 ). The d i s t r i b u t i o n o f b o tto m m a t e r i a l on th e m a in la n d s h e l f i s i l l u s t r a t e d i n F i g u r e s 2 , 3 and 4 ( S t e v e n s o n , U chupi and G o r s l i n e , 1959; F i g u r e s 12, 17 and 2 0 ) . The s e d im e n t p a t t e r n a l o n g much o f t h e s h e l f i s f a i r l y s im p l e . Seaw ard o f b e a c h e s , l i t t o r a l and s u b l i t t o r a l r o c k y a r e a s s e d im e n ts become p r o g r e s s i v e l y f i n e r , g r a d i n g fro m s a n d s to s i l t y s a n d s an d t h e n t o s a n d y s i l t s and s i l t s to w a rd th e edge o f t h e s h e l f . T h is g e n e r a l i z e d p a t t e r n o f s e d im e n t d i s t r i b u t i o n i s c h a r a c t e r i s t i c o f t h e c e n t r a l p o r t i o n o f th e P o i n t C o n c e p tio n s h e l f , th e Mugu s h e l f , t h e lo n g n a r ro w N ew p o rt-L a J o l l a s h e l f , and th e n o r t h e r n p o r t i o n o f t h e San D iego s h e l f . A r e a s o f m a jo r v a r i a t i o n fro m t h i s g e n e r a l i z e d p a t t e r n a r e th e f o l l o w i n g : ( 1 ) an e x t e n s i v e a r e a o f T ,g r e e n mud" ( s i l t o r san d y s i l t ) t h a t c o v e r s 45 to 50 p e r c e n t o f th e S a n t a B a r b a r a s h e l f , ( 2 ) a r e a s o f com plex s e d im e n ts Figure 2 Areal Distribution of Bottom Material on the Northern Section of the Mainland Shelf (Point Arguello to Point Dume) (Figure 12, Stevenson, Uchupi and Gorsline, 1959). 27 P I ARGUELLO TO PT DUME BOTTOM MATERIAL io c s •*« "> *'*tu- fmm* ocnrt OMtn < IM U T M M TO'fSC OCIVt M i l l OCIVf MCCH M.TT U OCIVt M tIM tAMOV H T OUVt MICK U T P T C O N C E P 77 ON SHELF r F ig u re 2 I 1 co oo Figure 3 Areal Distribution of Bottom Material on the Central Sec tion of the Mainland Shelf (Point Dume to Corona del Mar) (Figure 17, Stevenson, Uchupi and Gorsline, 1959). 29 1 0 ' 5 0 ' P T DUME TO CORONA DEL MAR BOTTOM M ATERIAL *T A T U T ( M IL C I •'■■'■'■WO FOOT COMTOUA LEGEND ROCK, GRAVEL A f = | OLIVE G R E E N ^ ■ . S H E L L FRA G M EN TS I 1 S IL T Y SAND | ! | j SANDY GRAVEL { £ ■ ] BLACK SANOY S IL T LIGHT OLIVE GREEN j j j j j DARK GRAY iiS d GRAVELLY SAND SANDY SILT r a m m HOCK. G RAVEL G LA O C O N B L A C K SELL P L A N T . D E B R IS B L A C K - fi n i 3 4 ° TTT1 CRS. T O FINE l l l l RED SAND OLIVE GREEN SANDY S IL T MED- TO VERY- FINE OLIVE fiR EFN e |i t OLIVE G REEN SAND ° LIVE G REEN SILT 3 0 , F ig u re 3 5 0 ' 4 0 ' 3 0 ' G L A U C O N IT E - 20 ' S A N PEDRO SHELF~ 1 0 ' RO C K . G RAVEL A N D S H E L L E R A & 1 1 8 ° 5 0 ' 5 0 ' O J o 3 0 ' 4 Figure 4 Areal Distribution of Bottom Material on the Southern Sec tion of the Mainland Shelf (Corona del Mar to San Diego) (Figure 20, Stevenson, Uchupi and Gorsline, 1959). 31 CORONA DEL MAR TO SAN DIEGO BOTTOM MATERIAL F ig u re 33 s u r r o u n d i n g o f f s h o r e r o c k y o u t - c r o p s on t h e c e n t r a l s h e l f p r o j e c t i o n i n S a n ta M o n ica Bay, on th e San P e d ro Bay s h e l f , and on th e s o u t h e r n p o r t i o n o f t h e San D ieg o s h e l f , (3 ) a r e a s o f c o a r s e sand ( e s p e c i a l l y r e l i c r e d sa n d ) on t h e S a n ta M onica Bay s h e l f , th e P a l o s V e rd e s s h e l f , t h e San P e d ro Bay s h e l f , and t h e s o u t h e r n p o r t i o n o f th e San D iego s h e l f , and ( 4 ) a r e a s o f s e d im e n t b l a c k e n e d by h y d ro g e n s u l f i d e r e s u l t i n g from w a s te d i s c h a r g e o p e r a t i o n s on t h e S a n ta M onica Bay s h e l f (Los A n g e le s C i t y O u t f a l l s ) , on th e P a lo s V e rd e s s h e l f (L o s A n g e le s C o u n ty O u t f a l l ) , and on t h e San P edro Bay s h e l f (Los A n g e le s H a r b o r ) ( R e i s h , 1959c; S te v e n s o n , U ch u p i and G o r s l i n e , 1 9 5 9 ). The h y d r o g ra p h y o f t h e s o u t h e r n C a l i f o r n i a n m a rin e r e g i o n i s sum m arized by Emery ( 1 9 6 0 ) . The s u r f a c e c u r r e n t p a t t e r n i s d o m in a te d by th e c o ld C a l i f o r n i a C u r r e n t moving s o u t h e a s t w a r d ; t h e n e a r s h o r e w a t e r s a r e d o m in a te d b y a l a r g e s lo w ly -m o v in g ed d y t h a t form s a c o u n t e r c u r r e n t . The w a te r a t i n t e r m e d i a t e d e p t h s i s o f s o u t h e r n o r i g i n . E n t r a i n m e n t o f w a te r by th e C a l i f o r n i a C u r r e n t a c r o s s t h e S a n t a R o sa - C o r t e s R id g e c a u s e s u p w e l l i n g o f th e i n t e r m e d i a t e w a t e r . N o r t h w e s t e r l y w in d s , p a r t i c u l a r l y n e a r P o i n t C o n c e p tio n , a l s o p r o d u c e u p w e l l i n g . F or a c o m p re h e n s iv e d e s c r i p t i o n o f th e s o u t h e r n C a l i f o r n i a n m a rin e r e g i o n s e e A p p e n d ix C o f t h i s p a p e r . 34 B e n t h i c S u rv e y s on t h e S o u th e rn C a l i f o r n i a n M a in la n d S h e l f The a p p l i c a t i o n o f q u a n t i t a t i v e sa m p lin g t e c h n i q u e s to t h e s t u d y o f b e n t h i c m a rin e i n v e r t e b r a t e p o p u l a t i o n s i n th e s e a o f f s o u t h e r n C a l i f o r n i a was n o t a t t e m p t e d u n t i l a f t e r W orld War I I . W ith t h e g r e a t i n f l u x o f p o p u l a t i o n to th e s o u t h e r n C a l i f o r n i a n a r e a d u r i n g and f o l l o w i n g th e w a r, t h e r e w as i n c r e a s e d c o n c e r n a b o u t t h e e f f e c t s of w a s te d i s c h a rg e o p e r a t i o n s i n th e m a rin e e n v i r o n m e n t. Most o f th e work d o n e in t h i s r e g i o n h a s b e e n m o t i v a t e d by t h i s c o n c e r n . Much o f t h i s work h a s b e e n s u p p o r t e d by g o v e rn m e n ta l a g e n c i e s such a s t h e C a l i f o r n i a F i s h and Game Com m ission, th e C a l i f o r n i a S t a t e W ater P o l l u t i o n C o n t r o l Board (now t h e C a l i f o r n i a S t a t e W ater Q u a l i t y C o n t r o l B o a r d ) , and th e U n ite d S t a t e s P u b l i c H e a l t h S e r v i c e , w hich a r e c h a rg e d w i t h th e r e s p o n s i b i l i t i e s o f th e p r e s e r v a t i o n o f n a t u r a l r e s o u r c e s and th e m a in te n a n c e o f p u b l i c h e a l t h . Bays and H a r b o rs Most o f t h e b a y s and h a r b o r s o f s o u t h e r n C a l i f o r n i a a r e s m a l l . N e a r l y a l l o f them h av e been s u b s t a n t i a l l y a l t e r e d by th e a c t i v i t i e s o f man. C o n s t r u c t i o n o f b r e a k w a t e r s , d r e d g i n g , th e d i v e r s i o n o f s t r e a m s , and w a s te d i s p o s a l o p e r a t i o n s have m o d if ie d t h e s e a r e a s t o su ch a d e g r e e t h a t l i t t l e o f t h e i r n a t u r a l e c o l o g i c a l c o n d i t i o n s i s p r e s e rv e d . 35 E a r l y i n 1951 Mr. R o b e rt P a u l , s a n i t a r y e n g i n e e r o f t h e D e p a rtm e n t o f F i s h and Game, S t a t e o f C a l i f o r n i a , r e q u e s t e d t h a t J . L. Mohr u n d e r t a k e w ith h i s g r a d u a t e s t u d e n t s a s u r v e y o f Los A n g e le s -L o n g B each H a rb o rs to p r o v id e b a c k g ro u n d f o r re c o m m e n d a tio n s on w a t e r u s e . Such a s u r v e y d e v e lo p e d o r g a n i c a l l y fro m th e e x i s t i n g p ro g ra m o f th e S o u t h e r n C a l i f o r n i a M arin e B o re r C o u n c i l , a g ro u p c o m p r is in g C a r r o l Wakeman, T e s t i n g E n g i n e e r , Los A n g e le s H a rb o r D e p a r t m e n t, H a ro ld S c h i l l e r , i n d u s t r i a l c h e m i s t , and b i o l o g i s t s o f t h e U n i v e r s i t y o f S o u th e r n C a l i f o r n i a , p a r t i c u l a r l y Mohr and J . L. B a r n a r d , C h a r l e s H o r v a th , and R. J . M e n z ie s , a l l o f whom d i d t h e s i s work on h a r b o r o r g a n is m s . The m a rin e b o r e r p ro g ra m i n c l u d e d m e a su re m e n ts o f p h y s i c a l v a r i a b l e s and b i o l o g i c a l a c t i v i t y on s t a n d a r d i z e d wooden t e s t b l o c k s a t 16 t o 24 s t a t i o n s i n th e h a r b o r s ; th e s u r v e y f o r Mr. P a u l ( t h e S t a t e o f C a l i f o r n i a ) i n v o l v e d th e a d d i t i o n o f a s m a ll b i o l o g i c a l d r e d g e and a No. 1 Hayward OPB m o d if ie d f o r u s e on one l i n e by Mr. H o rv a th a f t e r c o n s u l t a t i o n w i t h b i o l o g i s t s o f t h e S c r i p p s I n s t i t u t e o f O c e a n o g ra p h y . A bout e i g h t g r a d u a t e s t u d e n t s c a r r i e d on t h e p ro g ra m . D rs . O. H artm an and J . S. G a r th h e lp e d i n some a s p e c t s o f th e w o rk . R e p o r t s to t h e D e p a rtm e n t o f F i s h and Game became anonymous s t a t e d o cu m en ts an d some a p p e a r e d u n d e r th e l a b e l o f t h e new ly form ed R e g i o n a l W ater P o l l u t i o n C o n t r o l B o a rd . The m e th o d s and t h e e q u ip m e n t o f th e M a rin e B o re r C o u n c il g ro u p w ere u s e d by D. J . R e i s h , w o rk in g u n d e r a 36 U n i t e d S t a t e s P u b l i c H e a l t h S e r v i c e g r a n t .to. J . L. Mohr t o c o n t i n u e s t u d i e s o f th e e f f e c t o f w a s te d i s p o s a l on th e b e n t h i c p o p u l a t i o n s o f s o u t h e r n C a l i f o r n i a n m a rin e embay- m e n ts . R e i s h (1 9 5 5 ; 19 5 9 c; 1960; 1961b) c o n t i n u e d and e x panded t h e s e s t u d i e s , w hich have b e e n e x t e n d e d t o o t h e r man- made and m a n - a l t e r e d s o u t h e r n C a l i f o r n i a n em baym ents (Daw s o n , 1963; Newman, 1958; R e i s h , 1956; 196 0 ; 1961a; 1962; 1963a; and 1964; R e i s h and B a r n a r d , 1959; R e is h and W in te r , 1954; S to n e and R e i s h , 1 9 6 5 ). The e c o l o g i c a l s tu d y o f p o l l u t i o n i n th e Los A n g e le s -L o n g B each h a r b o r s ( R e i s h , 19-59c) i s th e m ost com p r e h e n s i v e i n v e s t i g a t i o n o f t h i s k in d i n t h i s r e g i o n . The p u r p o s e o f t h i s s t u d y i s t o d e s c r i b e th e b i o l o g i c a l , c h e m i c a l , and p h y s i c a l c h a r a c t e r i s t i c s o f a m a rin e h a r b o r t h a t i s g r o s s l y p o l l u t e d i n some a r e a s and l a r g e l y u n p o l l u t e d i n o t h e r s ( R e i s h , 1 959c, p . 1 ) . A t o t a l o f 235 o u t f a l l s d e l i v e r i n g i n d u s t r i a l , d o m e s tic and s to rm w a s t e s em pty i n t o th e h a r b o r s . R e i s h r a t h e r c o m p l e t e l y d e f i n e s t h e c h e m ic a l and p h y s i c a l e n v ir o n m e n t i n w h ich th e a n im a l p o p u l a t i o n s i n h a b i t i n g th e a r e a e x i s t . He d i s t i n g u i s h e s f i v e e c o l o g i c a l a r e a s t h a t v a r y i n t h e d e g r e e o f c o n t a m i n a t i o n and d i f f e r on th e b a s i s o f p r e v a l e n t p o l y - c h a e t e s p e c i e s . T h e se a r e ( 1 ) " v e r y p o l l u t e d b o t t o m , " c h a r a c t e r i z e d by no l i v i n g a n im a ls and b l a c k s lu d g e mud b e d s w i t h a s u l f i d e o d o r; ( 2 ) " p o l l u t e d b o t t o m s , " c h a r a c t e r i z e d by th e p o l y c h a e t e C a p i t e l l a c a p i t a t a and b l a c k mud p o s s e s s i n g a s u l f i d e o d o r ; ( 3 ) " s e m i - h e a l t h y b o tto m I , " 37 c h a r a c t e r i z e d by t h e p o l y c h a e t e s P o l y d o r a ( C a r a z z i a ) p a u c i b r a n c h i a t a and D o r v i l l e a a r t i c u l a t a and a v a r i e t y o f s u b s t r a t e t y p e s ; ( 4 ) ’'s e m i - h e a l t h y b o tto m I I , " c h a r a c t e r i z e d b y t h e p o l y c h a e t e C i r r i f o r m i a l u x u r i o s a and l e s s d i v e r s i f i e d s u b s t r a t e t y p e s ; ( 5 ) " h e a l t h y b o t t o m s , " c h a r a c t e r i z e d by a d i v e r s i t y o f m a rin e i n v e r t e b r a t e s i n c l u d i n g th e p o l y c h a e t e s T h a ry x p a r v u s , C o s s u r a C an d id a and N e r e i s p r o c e r a l i v i n g on b o tto m s c o n s i s t i n g p r i m a r i l y o f g r e y - c o l o r e d mud and c l a y . R e c e n t l y b e n t h i c m a rin e e x p l o r a t i o n o f B a h ia de San Q u i n t i n ( B a j a C a l i f o r n i a ) h a s p r o v id e d an e x c e l l e n t o p p o r t u n i t y t o o b t a i n b a s i c i n f o r m a t i o n c o n c e r n in g t h e e c o l o g y o f an u n p o l l u t e d m a rin e e n c l o s u r e ( B a r n a r d , 1962; 1964; R e i s h , 1 9 6 3 b ). T h i s b a y , l i k e th e b a y s o f s o u t h e r n C a l i f o r n i a , i s a p a r t o f t h e c o n t i n e n t a l b o r d e r l a n d m a r in e s y s te m ( s e e b e lo w ) . T h ese s t u d i e s s h o u ld be c o n s u l t e d by anyone d e s i r in g t o i n t e r p r e t t h e c h a n g e s b r o u g h t a b o u t b y m a r in e p o l l u t i o n i n t h e em baym ents o f s o u t h e r n C a l i f o r n i a . The SCUBA Zone F i e l d i n v e s t i g a t i o n s u t i l i z i n g s e l f - c o n t a i n e d u n d e r w a te r b r e a t h i n g a p p a r a t u s (SCUBA) have r e c e n t l y b e e n co n d u c te d t o i n v e s t i g a t e th e s u b l i t t o r a l b e n t h i c p o p u l a t i o n s i n s e v e r a l a r e a s a lo n g t h e s o u t h e r n C a l i f o r n i a n c o a s t . Many p ro b le m s can be a t t a c k e d by t h i s m ethod t h a t c a n n o t be s t u d i e d by t h e t r a d i t i o n a l m ethod o f g ra b d e v i c e s o p e r a t e d fro m s h i p s . The m ethod h a s b e e n s u c c e s s f u l l y a p p l i e d t o s u b l i t t o r a l ro c k y r e e f s ( P e q u e g n a t , 1961; 1 9 6 3 ), i n th e u n d e r w a te r t r a n s e c t s u r v e y t e c h n i q u e d e v e lo p e d by b i o l o g i s t - d i v e r s o f t h e C a l i f o r n i a D e p a rtm e n t o f F i s h and Game ( T u r n e r , E b e r t and G iv e n , 1964; 1965; 1 9 6 6 ) , t o th e s t u d y o f a r t i f i c a l r e e f s ( C a r l i s l e , T u rn e r and E b e r t , 1 9 6 4 ), f o r p e r i o d i c s a m p lin g o f s h a l l o w - w a t e r i n f a u n a l s p e c i e s ( F a g e r , 1 9 6 4 ), and i n th e c o l l e c t i o n o f m e io fa u n a sa m p le s (G iv e n and J o n e s , 1 9 6 2 ) . Much o f th e work by th e l a t e C onrad Limbaugh and by N o r th and h i s a s s o c i a t e s o f S c r i p p s I n s t i t u t i o n o f O c e a n o g ra p h y on th e e c o lo g y o f t h e k e l p b e d s o f s o u t h e r n C a l i f o r n i a was done u t i l i z i n g SCUBA e q u ip m e n t (L im baugh, 1955; N o r th and L e i g h t o n , 1962; C le n d e n n in g and N o r th , 1 9 6 0 ). U n f o r t u n a t e l y much o f t h i s i n f o r m a t i o n i s c o n t a i n e d o n ly i n th e p o o r l y c i r c u l a t e d m im eographed r e p o r t s o f th e I n s t i t u t e o f M arin e R e s o u r c e s ( S c r i p p s I n s t i t u t i o n o f O c e a n o g r a p h y ) . The M a in la n d S h e l f The f i r s t q u a n t i t a t i v e s a m p lin g o f t h e b e n t h o s o f t h e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f b e g a n i n 1952. H artm an (1 9 5 5 ; 1966) r e c o r d e d t h e o rg a n is m s fro m sa m p le s c o l l e c t e d a t 267 l o c a t i o n s f o rm in g a r e g u l a r g r i d b e tw e e n San P e d r o , C a l i f o r n i a and S a n ta C a t a l i n a I s l a n d . Sam ples w ere c o l l e c t e d from t h e V e le r o I V , r e s e a r c h v e s s e l o f t h e A l l a n H ancock F o u n d a tio n ( U n i v e r s i t y o f S o u t h e r n C a l i f o r n i a ) , u t i l i z i n g a m o d if ie d 2 c u b ic f o o t c a p a c i t y (= 5 6 .6 1) 39 Hayward S ta n d a r d o r a n g e - p e e l b u c k e t (Durham, 1955; B a rn a rd and J o n e s , 1 9 6 0 ). The s a m p lin g p ro g ram and s a m p lin g m eth o d s o f t h i s i n v e s t i g a t i o n were a p p r o p r i a t e f o r a q u a n t i t a t i v e a n a l y s i s o f t h e b i o t a o f a m a rin e r e g i o n . The San P e d r o Bay s h e l f , th e p o r t i o n o f t h e m a in l a n d s h e l f s t u d i e d by H artm an i n t h i s i n v e s t i g a t i o n , i s an a r e a o f e x tre m e s u b s t r a t e c o m p le x ity ( S t e v e n s o n , U ch u p i and G o r s l i n e , 1959; E m ery, 1960; H artm an, 1 9 5 5 ). P a u n a l d i v e r s i t y r e f l e c t s th e com plex s e d im e n t p a t t e r n . C o n s e q u e n tly , H artm an w as im p r e s s e d by t h e p a tc h y d i s t r i b u t i o n o f th e b i o t a . I n d e e d , " p a t c h i n e s s " h a s become an i n t e g r a l p a r t o f h e r i n t e r p r e t a t i o n o f th e c h a r a c t e r o f th e f a u n a o f th e m a in la n d s h e l f o f s o u t h e r n C a l i f o r n i a (H a rtm a n , 1955, p. 1 44; 1956, p . 20; i n S t e v e n s o n , 1961, pp. 1, 5; 1966, p. 1 9 0 ) . I t i s her c o n c l u s i o n t h a t " S p e c i f i c d i v e r s i t y i n s o u t h e r n C a l i f o r n i a i s so c h a r a c t e r i s t i c t h a t l a r g e - s c a l e c o m m u n itie s o f o r g a n is m s c a n n o t be i d e n t i f i e d " (H artm an , 1966, p . 1 9 0 ) . She makes e x c e p t i o n o n l y f o r th e L i s t r i o l o b u s a s s o c i a t i o n o f th e S a n ta B a r b a r a s h e l f ( B a r n a rd and H artm an , 1 9 5 9 ). W ilso n ( 1 9 5 6 ) c a t a l o g u e d t h e l i v i n g m o l l u s c a n s p e c i e s fro m t h e s a m p le s c o l l e c t e d by H artm an . Bandy (1 9 5 8 ) a n a ly z e d t h e d o m in a n t t r e n d s i n th e San P e d ro m o llu s c a n f a u n a b a s e d on t h e s y s t e m a t i c work o f W ils o n . In h i s m ethod, m o d if ie d fro m t h a t u s e d to d e m o n s t r a t e b i o f a c i e s o f b e n t h i c f o r a m i n i f e r a n s , r e l a t i v e ab u n d an ce i s c o n s i d e r e d t o 40 be o f m a jo r s i g n i f i c a n c e i n d e f i n i n g d e p t h z o n a t i o n and b i o f a c i e s . S u r p r i s i n g l y , Bandy u t i l i z e d a l l o f th e s a m p le s c o l l e c t e d a t H a rtm a n Ts s a m p lin g l o c a t i o n s w i t h o u t any r e s p e c t t o t h e i r g e o g r a p h i c l o c a t i o n . No d i s t i n c t i o n was made n o r any p r o v i s i o n made i n h i s t r e a t m e n t o f W ils o n ’ s d a t a t o a c c o u n t f o r e n v i r o n m e n ta l d i f f e r e n c e s t h a t e x i s t b e tw e e n th e n a r r o w , s t e e p , le e w a r d s h e l f o f S a n ta C a t a l i n a I s l a n d and t h e b r o a d , r e l a t i v e l y f l a t San P e d ro p o r t i o n o f t h e m a in la n d s h e l f . T h ese two e n v ir o n m e n ts a r e q u i t e d i f f e r e n t . H artm an (1 9 5 6 ) e x te n d e d h e r a n a l y s i s o f th e s o u t h e r n C a l i f o r n i a n b e n th o s w i t h a s tu d y o f th e f a u n a o f S a n t a M o n ica Bay, b u t t h e s e r e s u l t s a r e in c o m p le te f o r some p h y l e t i c g r o u p s . The t e c h n i q u e s em ployed w ere t h o s e o f th e San P e d ro s t u d y and sam ple a n a l y s i s was i n c o m p l e t e ; w hat r e s u l t s th e n a l s o am ounts t o a q u a l i t a t i v e s t u d y . A g a in H artm an was im p r e s s e d w ith th e h i g h d e g r e e o f f a u n a l d i v e r s i t y w hich sh e d e s c r i b e d a s " p a t c h i n e s s . ” As t h e p r im a r y m o tiv e f o r t h i s i n v e s t i g a t i o n was t o a s s e s s th e p o s s i b l e e f f e c t s of p o l l u t i o n on t h e m a r in e f a u n a and t o d e t a i l t h e s t a t e o f t h e b i o t a p r i o r t o an e x p a n s i o n o f w a s te d i s p o s a l o p e r a t i o n s i n t h i s r e g i o n , c e r t a i n o f th e m a jo r c o n c l u s i o n s w ere o r i e n t e d in t h i s d i r e c t i o n . H artm an found t h a t p o l l u t i o n had in d e e d a d v e r s e l y a f f e c t e d th e b i o t a ; she i d e n t i f i e d t h e f o l l o w i n g c o n c e n t r i c z o n e s a ro u n d t h e o u t f a l l t e r m i n u s : ( 1 ) t h e " l i m i t e d p o l l u t i o n f a u n a ” ( s p e c i e s few and s m a l l ; e c h in o d e r m s , s m a ll c r u s t a c e a n s and m o l l u s k s a b s e n t or 41 s p a r s e ) ; (2 ) th e " p o l l u t i o n t o l e r a n t f a u n a " ( s p e c i e s more num erous and l a r g e r ; i n c r e a s i n g num bers o f e c h in o d e r m s , m o llu s k s and s m a ll c r u s t a c e a n s ) ; ( 3 ) t h e " l i m i t e d e n r i c h e d f a u n a " (fe w s p e c i e s , many i n d i v i d u a l s and h ig h b i o m a s s ) ; and ( 4 ) th e " u n l i m i t e d d i m i n i s h e d f a u n a " ( i n c r e a s i n g nu m b ers o f k i n d s , b u t d i m i n i s h e d p e a k s o f b i o m a s s ) . The A l l a n H ancock F o u n d a tio n S u rv ey o f th e S o u th e rn C a l i f o r n i a n M a in la n d S h e l f B e g in n in g i n 1956 t h e s a m p lin g p ro g ra m o f t h e A l l a n H ancock F o u n d a tio n was e x te n d e d t o a l l o f t h e m a in la n d s h e l f o f s o u t h e r n C a l i f o r n i a fro m P o i n t C o n c e p tio n t o t h e M ex ic an b o r d e r . T h is c o m p re h e n s iv e s u r v e y w as s u p p o r t e d b y th e C a l i f o r n i a S t a t e W ater P o l l u t i o n C o n t r o l B oard (now te rm e d th e S t a t e W ater Q u a l i t y C o n t r o l B o a r d ) ; t h e U n i v e r s i t y p r o v id e d th e f a c i l i t i e s o f t h e F o u n d a tio n and t h e l a t e C a p t a i n G. A l l a n H ancock f i n a n c e d some c r u i s e s o f th e R/V V e le r o IV . M ethods o f S a m p lin g and A n a l y s i s A d i s c u s s i o n o f t h e s a m p lin g m ethods em ployed d u r i n g th e A l l a n H ancock F o u n d a t i o n S u rv e y o f th e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f i s p r e r e q u i s i t e t o any p r e s e n t a t i o n o f th e r e s u l t s o f t h a t p r o j e c t or t o t h e f u r t h e r u t i l i z a t i o n o f th e p r o j e c t ’ s d a t a i n a d d i t i o n a l a n a l y s e s . I n d e e d , t h e f i e l d and l a b o r a t o r y m eth o d s o f t h a t p r o j e c t a r e t h e f i e l d and l a b o r a t o r y m e th o d s o f t h e c u r r e n t i n v e s t i g a t i o n . Deep w a te r s a m p le s w ere c o l l e c t e d a b o a rd t h e 42 r e s e a r c h v e s s e l V e le r o IV by means o f a m o d if ie d Hayward s t a n d a r d o r a n g e - p e e l b u c k e t (OPB) w ith an a r e a l c o v e ra g e o f 2 - 3 / 5 s q u a r e f e e t ( c a . 0 .2 5 m3 ) and a r a t e d c a p a c i t y o f 2 c u b ic f e e t ( 5 6 .6 l i t e r s ) . The n e a r s h o r e p o r t i o n o f th e s h e l f , i n w a t e r d e p t h s o f 2 . 4 t o 1 0 .1 m e t e r s , was sam pled fro m th e m otor la u n c h o f t h e R/V V e le ro IV u s in g a m o d ifie d l / l O s q u a r e m e te r Van Veen g r a b . The m ethods u t i l i z e d f o r th e s h ip b o a r d p r o c e s s i n g and t h e l a b o r a t o r y a n a l y s i s of t h e s e sa m p le s a r e d e s c r i b e d by Durham (1 9 5 5 ) and B a rn a rd and J o n e s ( 1 9 6 0 ) . The a n im a ls c o l l e c t e d w ere l i m i t e d by th e s i z e o f th e mesh ( s q u a r e o p e n in g s o f 0 .7 m i l l i m e t e r s ) th ro u g h w h ich s e d im e n ts were s c r e e n e d a b o a rd s h i p . The p r e s e r v a t i v e u se d was 10 p e r c e n t s e a w a te r f o r m a l i n . The t r e a t m e n t a c c o rd e d b e n t h i c sa m p le s i n th e l a b o r a t o r y in v o lv e d th e f o l l o w i n g p r o c e d u r e s : ( 1 ) p r o c e s s i n g was c o m p leted by w a sh in g and f l o t a t i o n , ( 2 ) s t a n d i n g c r o p , m easured a s w et w e ig h t i n g ra m s, was d e te r m in e d by p h y l e t i c g ro u p s (m ethod o f T h o rs o n , 1 9 5 7 ), ( 3 ) th e l a r g e s t and m ost c o n s p ic u o u s s p e c i e s w ere d e t e r m in e d , and ( 4 ) a l l a n im a ls g r e a t e r t h a n 1 m i l l i m e t e r ( l e a s t d im e n s io n ) w ere s o r t e d and i d e n t i f i e d . S p e c i f i c d e t e r m i n a t i o n s were made by t h e f o l low ing s c i e n t i s t s o f th e A l l a n Hancock F o u n d a tio n : D r. O lg a H artm an, p o l y c h a e t o u s a n n e l i d s ; D r. J . L a u re n s B a rn a rd (now w ith t h e U. S . N a t i o n a l Museum), c r u s t a c e a n s e x c e p t i n g cum aceans; Mr. R o b e r t R. G iv e n , cum aceans; C a p t a i n F re d C. Z ie s e n h e n n e , e c h in o d e rm s ; and th e a u t h o r , m o l l u s k s . 43 The o rg a n is m s s t u d i e d i n t h i s s u r v e y a r e t h e i n v e r t e b r a t e m e ta z o a n s t h a t w ere c a p t u r a b l e by th e OPB and Van Veen g r a b and w ere l a r g e e n o u g h t o be r e t a i n e d b y th e s i e v e em ployed i n sam ple p r o c e s s i n g . T h e se o b v i o u s l y r e p r e s e n t o n ly a f r a c t i o n o f t h e f a u n a . E x c lu d e d a r e any m o t i l e a n i m als t h a t e s c a p e d c a p t u r e , an y d e e p - b u r r o w in g a n im a ls l i v i n g b elo w t h e d e p th o f p e n e t r a t i o n o f t h e g r a b , and t h e f a u n a t h a t p a s s e d t h r o u g h t h e s i e v e s i n th e s c r e e n i n g p r o c e s s . The f a u n a o f c o n s o l i d a t e d s e d i m e n t s , r o c k s i n p l a c e , was n o t s a m p le d . Only a d e f i n e d a r b i t r a r y f r a c t i o n o f t h e f a u n a , " t h e b e n t h i c m a c ro fa u n a o f u n c o n s o l i d a t e d s e d i m e n t s , " o f t h e l i m i t e d s t u d y a r e a , " t h e m a in la n d s h e l f , " was i n v e s t i g a t e d . The d e t e r m i n a t i o n o f a s s o c i a t i o n s ( te r m e d "com m uni t i e s " ) on t h e m a in la n d s h e l f was made b y D r. J . L a u re n s B a r n a r d o f t h e A l l a n H ancock F o u n d a tio n S u rv e y S t a f f . At f i r s t he a t t e m p t e d to f o l l o w th e s y s te m o u t l i n e d by T h o rs o n (1 9 5 7 , p . 477) b u t ab an d o n ed i t a s u n w o rk a b le . I n s t e a d he u t i l i z e d a s y s te m w h e re b y t h e "d o m in a n t a n i m a l s , " f o r w h ic h t h e a s s o c i a t i o n s a r e nam ed, w ere d e t e r m in e d by t h e i r r a n k i n s t a n d i n g c r o p . " A l l s a m p le s a l l o c a t e d t o a community m ust h av e t h e a p p r o p r i a t e a n i m a l s d o m in a tin g i n th e u p p e r r a n k s o f 1 to 4” ( B a r n a r d [ a ] , i n S t e v e n s o n , 1 961, p . 2 3 ) . T h e re was no f i x e d m a t h e m a t i c a l way t o d e f i n e " d o m in a n ts " (n o f i x e d lo w e r l i m i t ) and i n t h i s s e n s e th e s y ste m i s s u b j e c t i v e . U n l i k e T h o r s o n Ts m eth o d , B a r n a r d Ts r e q u i r e d t h a t a sam ple f i t t h e r e q u i r e d c r i t e r i o n t o be a l l o c a t e d t o an 44 a s s o c i a t i o n ; t h o s e sam p les t h a t d i d n o t were l a b e l e d "n o d o m in a n t" ( B a r n a r d [ a ] , i n S t e v e n s o n , 1 9 6 1 ). Some o f th e a s s o c i a t i o n s d e r i v e d by t h i s method w ere i d e n t i f i e d b y two "d o m in a n t a n i m a l s " (= " c o - d o m i n a n t s " ) . The d i s t r i b u t i o n s o f t h e s e a s s o c i a t i o n s are mapped on t h e b a s i s o f t h i s a n a l y s i s . S e d im e n ta ry a n a l y s e s were made by t h e g e o l o g i s t s o f th e A l l a n Hancock F o u n d a tio n Survey S t a f f u s i n g t h e f o l l o w in g t e c h n i q u e s : ( 1 ) g r a i n s i z e by a s e t t l i n g tu b e (E m ery , 1938) and a p i p e t t e method ( R i t t e n h o u s e , 1 9 3 9 ) , (2 ) p e r c e n t c a lc iu m c a r b o n a t e by a g a s o m e t r i c m ethod ( B i e n , 1 9 5 2 ), and (3 ) p e r c e n t o r g a n i c n i t r o g e n by t h e K j e l d a h l method ( N i e d e r l and N i e d e r l , 1947) . The s o r t i n g c o e f f i c i e n t s r e p o r te d a r e by t h e method o f T ra s k (K rum bein and P e t t i j o h n , 1 9 3 8 ). A d e t a i l e d d i s c u s s i o n o f th e m eth o d s o f s a m p lin g and a n a l y s i s em ployed by t h e s u rv e y g e o l o g i s t s i s i n c l u d e d i n A p p e n d ix B o f t h i s p a p e r . H y d r o g ra p h ic a n a l y s e s were made by t h e o c e a n o g r a p h e rs o f th e A l l a n Hancock F o u n d a tio n S u rv e y S t a f f u s i n g th e f o l l o w i n g t e c h n i q u e s : ( 1 ) w a te r t e m p e r a t u r e s by a 2 0 0 - f o o t b a th y th e r m o g r a p h and a l a b o r a t o r y th e rm o m e te r ( s u r f a c e t e m p e r a t u r e s ) (AHF:USC, 1 9 6 5 ) , (2 ) v i s u a l t r a n s p a r e n c y w ith a S e c c h i d i s k (AHF:USC, 1 9 6 5 ) , (3) s a l i n i t y b y t i t r a t i o n w ith s i l v e r n i t r a t e u s in g a p o t a s s i u m ch ro m a te i n d i c a t o r and c a l i b r a t e d a g a i n s t an a p p r o p r i a t e " w a te r s t a n d a r d " (AHF:USC, 1965; S v e r d ru p , J o h n s o n a n d F le m in g , 1 9 4 2 ), (4 ) d i s s o l v e d oxygen by th e P o m ero y -K irch m an ( 1 9 4 5 , c i t e d i n S t a f f , AHF, 1958) m o d i f i c a t i o n o f t h e W in k le r m e th o d , (5) i n o r g a n i c p h o s p h a te by a c o l o r i m e t r i c m ethod (R o b in s o n and Thompson, 1948, c i t e d i n S t a f f , AHF, 1 9 5 8 ), (6 ) i n o r g a n i c s i l i c a t e by a c o l o r i m e t r i c m ethod (R o b in so n an d Thompson, 1948, c i t e d i n S t a f f , AHF, 1 9 5 8 ), and ( 7 ) i n o r g a n i c n i t r a t e by two m eth o d s (AHFrUSC, 1 9 6 5 ). A l l w a te r s a m p le s w ere c o l l e c t e d fro m d e p t h u s i n g Nansen r e v e r s i n g b o t t l e s ; a b u c k e t was u s e d t o c o l l e c t s u r f a c e w a te r s a m p le s . T h e se h y d r o - g r a p h i c m eth o d s a r e d i s c u s s e d i n d e t a i l i n A p p e n d ix B o f t h i s p a p e r . A Summary o f th e R e s u l t s o f t h e A l l a n H ancock F o u n d a tio n S u r v e y : th e B e n t h i c M a c ro fa u n a T h re e m a jo r a n i m a l a s s o c i a t i o n s o c c u r on t h e n o r t h e r n p o r t i o n o f th e m a in la n d s h e l f : th e A m p h io d ia - C a r d i t a , th e L i s t r i o l o b u s , and t h e N o t h r i a - T e l l i n a a s s o c i a t i o n s (B a r n a rd and H artm an , 1959; B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). F i g u r e s 5 and 6 i l l u s t r a t e t h e i r g e o g r a p h i c d i s t r i b u t i o n s . The A m p h io d ia - C a r d i t a a s s o c i a t i o n i s a m o d i f i c a t i o n o f t h e more e x t e n s i v e l y d i s t r i b u t e d o p h i u r o i d a s s o c i a t i o n " d o m in a te d " by t h e sm ooth re d o p h i u r o i d A m p h io d ia u r t i c a . The " c o - d o m i n a n t " C a r d i t a v e n t r i c o s a i s a p e le c y p o d m o l l u s k . The A m p h io d ia - C a r d i t a a s s o c i a t i o n i s th e p r o m in e n t f e a t u r e o f t h e b i o t a o f t h e P o i n t C o n c e p tio n s h e l f b e tw e e n t h e s h a l l o w - s h e l f b e n t h o s and th e d e e p - w a t e r b e n t h o s , t h u s Figure 5 The D i s t r i b u t i o n o f B e n th ic M a c ro f a u n a l A s s o c i a t i o n s on th e M ain lan d S h e l f , P o i n t A r g u e l l o ( P o i n t C o n c e p tio n ) to S a n ta B a r b a r a ( F ig u r e 46, B a rn a rd [a ], i n S te v e n s o n , 1 9 6 1 ). N o te: O nly t h e m a jo r ( w id e ly d i s t r i b u t e d ) a s s o c i a t i o n s a r e mapped; th e sm oothed c u r v e s o f t h i s map p r e s e n t a somewhat i d e a l i z e d v e r s i o n o f t h e s e d i s t r i b u t i o n s o b s c u r in g s l i g h t l y more r e t i c u l a t e d p a t t e r n s . 46 50‘ 2 t f S O f 40' PT. ARGUELLO SANTA BARBARA w > V , Diopotro Amphiodia -Cardita Litttiolobut N o th ria -T e llin o STATlftC ITILCI PT. ARGUELLO TO SANTA BARBARA C O M M U N IT IE S Figure 5 - < i Figure 6 The D i s t r i b u t i o n o f B e n t h i c M a c ro fa u n a l A s s o c i a t i o n s on t h e M a in la n d S h e l f , S a n ta B a r b a r a t o P o i n t Dume ( F ig u r e 4 7 , B a r n a r d l a ] , i n S te v e n s o n , 1 9 6 1 ). N o te: O n ly th e m a jo r ( w i d e l y d i s t r i b u t e d ) a s s o c i a t i o n s a r e m apped; th e sm oothed c u r v e s o f t h i s map p r e s e n t a somewhat i d e a l i z e d v e r s i o n o f t h e s e d i s t r i b u t i o n s o b s c u r in g s l i g h t l y more r e t i c u l a t e d p a t t e r n s . The a s s o c i a t i o n l i s t e d i n th e l e g e n d as ,T C h l o e i a tT i s th e P e c t i n a r i a - C h l o e i a a s s o c i a t i o n . 48 VENTURA v»\ v A m p h io d ia C o rd ite SANTA BARBARA TO POINT DUME N othria — Tellino COMMUNITIES \ \ \ Figure 6 •f* v D 50 f o rm in g a r o u g h ly banded p a t t e r n o f a n im a l a g g r e g a t i o n s . The A m p h io d ia - C a r d i t a a s s o c i a t i o n a l s o e x te n d s a c r o s s th e S a n ta B a r b a r a s h e l f and i s a n i m p o r t a n t f e a t u r e o f t h i s a r e a . S o u th o f Hueneme s u b m a rin e c a n y o n t h i s a s s o c i a t i o n i s no l o n g e r a p a r t o f th e s h e l f b i o t a . I n f a c t , t h e "d o m i n a n t" C a r d i t a v e n t r i c o s a i n h a b i t s t h e s lo p e o f San P e d ro B asin w h ere i t s c e n t e r o f d i s t r i b u t i o n i s b e tw e e n 220 and 366 m e t e r s (s e e "D om inant P e le c y p o d F au n a 6 , " i n Bandy, 1958) ( B a r n a r d and Z i e s e n h e n n e , 1961; G. J o n e s , 1 9 6 4 ). I n s h o r e fro m th e A m p h io d ia - C a r d i t a a s s o c i a t i o n , i n th e l a r g e s i l t d e p o s i t of t h e S a n ta B a r b a r a s h e l f and i n a s i m i l a r d e p o s i t on th e P o i n t C o n c e p tio n s h e l f , i s a u n iq u e a s s o c i a t i o n " d o m in a te d ” by t h e e c h i u r o i d L i s t r i o l o b u s p e lo d e s ( B a r n a r d and H artm an , 1 9 5 9 ). T h is a s s o c i a t i o n o c c u r s i n d e p t h s o f 30 m e te r s t o 60 m e t e r s w i t h i t s g r e a t e s t d e v e lo p m e n t a lo n g th e 37 m e te r c o n t o u r where t h e mean number o f L i s t r i o l o b u s i s 1 0 0 / s q u a r e m e t e r , r e p r e s e n t i n g a s t a n d i n g c ro p o f a b o u t 1000 g r a m s /s q u a r e m e te r (w et w e i g h t ) . The e a s tw a r d e x t e n s i o n o f t h i s a s s o c i a t i o n n a rro w s o f f V e n tu r a and m e rg e s w ith t h e N o t h r i a - T e l l i n a a s s o c i a t i o n . Beyond t h i s p o i n t th e L i s t r i o l o b u s a s s o c i a t i o n d o e s n o t a p p e a r a s a d i s t i n c t f a u n a l u n i t ( B a r n a r d and H a rtm a n , 1 9 5 9 ; G. J o n e s , 1 9 6 4 ). In s h a l l o w e r w a t e r , w here s e d im e n t s a r e c o a r s e r , s e v e r a l a n im a l a s s o c i a t i o n s i n h a b i t t h e b o tto m . The D i o p a t r a o r n a t a a s s o c i a t i o n o c c u r s i n a r e a s w h ere k e l p and 51 " r u b b l e " ( b r o k e n r o c k , g r a v e l and s h e l l s ) a r e p r o m i n e n t . T h is a s s o c i a t i o n i s w i d e l y d i s t r i b u t e d on th e i n n e r p o r t i o n o f th e P o i n t C o n c e p tio n segm ent o f t h e s h e l f , b u t i s p r o b a b l y n o t a s e x t e n s i v e l y d i s t r i b u t e d a s i n d i c a t e d i n F ig u r e 5. The N o t h r i a e l e g a n s - T e l l i n a b u t t o n i a s s o c i a t i o n i s an im p o r t a n t f e a t u r e o f t h e S a n ta B a r b a r a s h e l f b i o t a . A long m o st p a r t s o f t h e m a in la n d s h e l f t h e N o t h r i a - T e l l i n a a s s o c i a t i o n i s r e s t r i c t e d t o b o tto m s n e a r s h o r e and o c c u r s o n ly a s a n a r ro w b e l t i n s h o r e o f t h e Li s t r i o l o b u s a s s o c i a t i o n i n th e w e s t e r n p o r t i o n o f th e S a n t a B a r b a r a s h e l f . H ow ever, s e d im e n ts on t h e e a s t e r n p o r t i o n o f t h e S a n ta B a r b a r a s h e l f , o f f V e n t u r a , a r e much c o a r s e r t h a n t h o s e t o t h e w e s t . Here e x t e n s i v e sa n d b o tto m s p r e s e n t a s u i t a b l e h a b i t a t i n w h ich t h e N o t h r i a - T e l l i n a a s s o c i a t i o n can e x t e n d f a r fro m s h o re ( B a r n a r d and H artm an , 1959; B a r n a r d , 1963; G. J o n e s , 1 9 6 4 ). P r i o n o s p i o m a l m g r e n i , a s m a l l p o l y c h a e t e , i s th e m o st c o n s p ic u o u s f a u n a l e le m e n t i n an a s s o c i a t i o n t h a t p o p u l a t e s t h e m a j o r i t y o f t h e san d b o tto m s i n w a t e r d e p t h s o f l e s s th a n 10 m e t e r s ( B a r n a r d , 1 9 6 3 ). Seaw ard o f th e A m p h io d ia - C a r d i t a a s s o c i a t i o n o f t h e n o r t h e r n p o r t i o n o f t h e m a in la n d s h e l f and o f t h e A m phiodia u r t i c a a s s o c i a t i o n a lo n g th e s o u t h e r n p o r t i o n s o f t h e s h e l f , b o tto m s o f t h e d e e p s h e l f and s lo p e a r e p o p u l a t e d b y a s s o c i a t i o n s i n w h ich t h e p o l y c h a e t e s Q n u p h is n e b u l o s a , P e c t i n a r i a c a l i f o r n i e n s i s , C h l o e i a p i n n a t a , T r a v i s i a pupa and P i s t a d i s j u n c t a , t h e o p h i u r o i d s A m phia'cantha 52 am p h a c a n th a and A m phiodia d i g i t a t a , t h e e c h i n o i d s B r i s a s t e r to w n s e n d i and B r i s s o p s i s p a c i f i c a and t h e p e le c y p o d m o llu s k s A c i l a c a s t r e n s i s and Amygdalum p a l l i d u l u m a r e p r o m in e n t. T h is d e e p e r s h e l f f a u n a i s common t o a l l o f t h e a r e a s o f th e m a in la n d s h e l f . The P e c t i n a r i a - C h l o e i a a s s o c i a t i o n , th e m ost w i d e l y d i s t r i b u t e d f e a t u r e o f t h e o u t e r s h e l f and s l o p e b i o t a , i s n o t a d e q u a t e l y r e p r e s e n t e d i n F i g u r e s 5, 6, 7 and 8 . S o u th o f Hueneme su b m a rin e can y o n th e A m phiodia u r t i c a a s s o c i a t i o n o c c u r s g e n e r a l l y on t h e o u t e r p o r t i o n a lo n g th e e n t i r e l e n g t h o f th e s o u t h e r n s h e l f . The e x t e n t o f i t s d e v e lo p m e n t i s v a r i a b l e and i t s d i s t r i b u t i o n i s d i s c o n t i n u o u s ( F i g u r e s 7 and 8 ) . I t i s r e d u c e d o r m is s in g i n a r e a s o f s u b s t r a t e c o m p l e x i t y su c h a s th e c e n t r a l s h e l f p r o j e c t i o n i n S a n t a M onica Bay, th e P a l o s V e rd e s S h e l f , t h e San P e d ro Bay S h e l f and t h e s o u t h e r n p o r t i o n o f t h e San D ieg o S h e l f ( B a r n a r d and Z ie s e n h e n n e , 1961; G. J o n e s , 1 9 6 4 ). I n s h o r e o f th e A m p h io d ia a s s o c i a t i o n , i n m ost r e g i o n s , san d b o tto m s a r e p o p u l a t e d by a s s o c i a t i o n s s i m i l a r to t h o s e p r o m in e n t i n t h e s h a l l o w r e g i o n s o f t h e n o r t h e r n p a r t o f th e m a in la n d s h e l f . The m o st i m p o r t a n t o f t h e s e a r e t h e N o t h r i a - T e l l i n a , D i o p a t r a and P r i o n o s p i o a s s o c i a t i o n s . The r e g i o n s g e n e r a l l y c o n fo rm in g t o t h i s p a t t e r n o f f a u n a l a s s o c i a t i o n s a r e ( 1 ) t h e s h o r t , n a rro w Mugu s h e l f , ( 2 ) t h e n o r t h e r n p o r t i o n o f t h e S a n t a M onica Bay s h e l f , (3 ) t h e lo n g b u t n a rro w N ew p o rt-L a J o l l a s h e l f , and ( 4 ) t o Figure 7 The D i s t r i b u t i o n o f B e n t h i c M a c r o f a u n a l A s s o c i a t i o n s on t h e M a in la n d S h e l f , P o i n t Dume t o N ew p o rt ( F i g u r e 4 8 , B a r n a r d [ a ] , i n S t e v e n s o n , 1 9 6 1 ) . N o t e : O nly t h e m a jo r ( w i d e l y d i s t r i b u t e d ) a s s o c i a t i o n s a r e m apped; t h e sm o o th e d c u r v e s o f t h i s map p r e s e n t a som ew hat i d e a l i z e d v e r s i o n o f t h e s e d i s t r i b u t i o n s o b s c u r i n g s l i g h t l y m ore r e t i c u l a t e d p a t t e r n s . The a s s o c i a t i o n l i s t e d i n t h e l e g e n d a s lfC h l o e i a lr i s t h e P e c t i n a r i a - C h l o e i a a s s o c i a t i o n . 53 A m phiodia POINT DUME TO NEWPORT \ \ C O M M U N IT IE S Figure 7 U l r Figure 8 The D i s t r i b u t i o n o f B e n t h i c M a c ro fa u n a l A s s o c i a t i o n s on t h e M a in la n d S h e l f , N ew port t o M exico ( F ig u r e 4 9 , B a rn a rd [ a ] , i n S t e v e n s o n , 1 9 6 1 ) . N o te : O nly t h e m ajo r ( w i d e l y d i s t r i b u t e d ) a s s o c i a t i o n s a r e m apped; t h e sm oothed c u r v e s o f t h i s map p r e s e n t a som ew hat i d e a l i z e d v e r s i o n o f t h e s e d i s t r i b u t i o n s o b s c u r i n g s l i g h t l y more r e t i c u l a t e d p a t t e r n s . 55 NEW PORT TO MEXICO COM M UNITIES Figure 8 L a o 57 a l e s s e r e x t e n t t h e n o r t h e r n p o r t i o n o f t h e San D ieg o s h e l f . The r e m a i n i n g p o r t i o n s o f t h e s o u t h e r n p a r t o f t h e m a in la n d s h e l f a r e c h a r a c t e r i z e d by c o m p le x p a t t e r n s o f s u b s t r a t e and f a u n a l a s s o c i a t i o n s . Much o f t h e S a n t a M o n ic a Bay S h e l f , t h e P a l o s V e rd e s S h e l f , t h e S an P e d r o Bay S h e l f an d t h e s o u t h e r n p o r t i o n o f t h e San D ie g o S h e l f a r e c h a r a c t e r i z e d by r e t i c u l a t e d ( o r p a t c h y ) d i s t r i b u t i o n p a t t e r n s . N e a r l y a d o z e n a s s o c i a t i o n s e x i s t i n t h e s e a r e a s . I n a d d i t i o n t o t h e w i d e l y d i s t r i b u t e d A m p h io d ia , N o t h r i a - T e l l i n a , D i o p a t r a and P r i o n o s p i o a s s o c i a t i o n s , t h e r e a r e a num ber o f r a t h e r s p e c i a l i z e d a s s o c i a t i o n s w h ic h o c c u p y o n l y a s m a l l f r a c t i o n o f t h e b o t t o m a r e a . T h e s e m in o r a s s o c i a t i o n s w e re i n f r e q u e n t l y s a m p le d and h e n c e a r e p o o r l y know n. T h e i r d i s t r i b u t i o n s a r e n o t shown i n F i g u r e s 7 and 8 . T h re e s o u t h e r n s h e l f a s s o c i a t i o n s m e r i t a t t e n t i o n ; t h e s e a r e t h e A m p h io p lu s h e x a c a n t h u s a s s o c i a t i o n o f t h e San P e d r o Bay s h e l f , t h e N o t h r i a s t i g m a t i s - S p i o p h a n e s bombyx a s s o c i a t i o n o r " r e d s a n d " a s s o c i a t i o n o f a l l f o u r r e g i o n s o f c o m p le x s u b s t r a t e p a t t e r n s , and t h e C h a e t o p t e r u s v a r i o p e d a t u s com m unity o f t h e P a l o s V e r d e s s h e l f . The A m p h io p lu s h e x a c a n t h u s a s s o c i a t i o n i s a m o d i f i c a t i o n o f t h e A m p h io d ia u r t i c a a s s o c i a t i o n ( F i g u r e 7 ) . The l a t t e r s p e c i e s i s c o n s i d e r e d " s u b d o m i n a n t " ( B a r n a r d and Z i e s e n h e n n e , 1 9 6 1 ) . The i n a r t i c u l a t e b r a c h i o p o d G l o t t i d i a a l b i d a r e a c h e s i t s maximum a b u n d a n c e i n t h i s a s s o c i a t i o n ( J o n e s and B a r n a r d , 1 9 6 3 ) . 58 The r e l i c c o a r s e r e d ( i r o n o x id e s t a i n e d ) sa n d d e p o s i t s a r e th e m ost d i s t i n c t i v e c o a r s e f r a c t i o n ty p e on t h e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f . The m a c r o fa u n a o f t h i s s u b s t r a t e - t y p e i s e q u a l l y i n t e r e s t i n g . The p o l y c h a e t e s N o t h r i a s t i g m a t i s and S p io p h a n e s bombyx a r e th e m o st p r o m i n e n t i n v e r t e b r a t e s . The N o t h r i a - S p io p h a n e s a s s o c i a t i o n i s i l l u s t r a t e d o n ly i n F i g u r e 8 ( " S p io p h a n e s bombyx and N o t h r i a s t i g m a t i s " ) . A u n iq u e f e a t u r e o f th e b i o t a on t h e P a l o s V erd es s h e l f i s th e C h a e t o p t e r u s a s s o c i a t i o n . I n r e l a t i v e l y s h a l low d e p t h s c l o s e t o s h o r e t h e p a rc h m e n t worm C h a e t o p t e r u s v a r i o p e d a t u s fo rm s m a sse s o f i t s t u b e s on b l a c k e n e d s e d i m e n ts. P r o m in e n t w ith i t i s th e p e le c y p o d Lima d e h i s c e n s . T h is a s s o c i a t i o n i s n o t i n d i c a t e d on F i g u r e 7. A p p e n d ix D o f t h i s p a p e r i n c l u d e s a c o m p re h e n siv e d i s c u s s i o n o f t h e r e s u l t s o f th e A l l a n H ancock F o u n d a tio n S u rv e y p e r t a i n i n g to t h e b e n t h i c m a c r o fa u n a o f t h e s h e l f . The R e p o r t s o f th e A l l a n Hancock F o u n d a tio n S u rv e y A f i n a l r e p o r t , e d i t e d b y D r. R o b e r t E. S te v e n s o n , P r o j e c t D i r e c t o r , was s u b m i t t e d t o t h e S t a t e W ater P o l l u t i o n C o n t r o l B oard u n d e r t h e t i t l e "The O c e an o g rap h y o f t h e S o u th e r n C a l i f o r n i a M a in la n d S h e l f " and b e a r i n g t h e d a t e A u g u st 31, 1 9 6 1 . As s u b m i t t e d i t c o m p ris e d f i v e v o lu m e s: Volume I , S e c t i o n I . The Sea o v e r t h e M a in la n d S h e l f o f S o u th e r n C a l i f o r n i a , 116 p a g e s , 59 B. C. Volume A. B. Volume Volume Volume A. B. 182 f i g u r e s . The sea o v e r th e m a in la n d s h e l f of s o u t h e r n C a l i f o r n i a , by R o b e r t E. S te v e n s o n l a ] , p a g e s 3 - 5 2 , f i g u r e s 1-3 5 ; C hem ical a n d p h y s i c a l p r o p e r t i e s of t h e w a te r o v e r t h e m a in la n d s h e l f , 1 9 5 9 -1 9 6 0 , b y R ic h a rd B. T ib b y , pages 5 3 - 1 1 6 , f i g u r e s 36-122; The s t a t e o f th e s h e l f s e a , b y R o b e rt E . S te v e n s o n [ b ] , p a g e s 11 7 -1 6 6 , f i g u r e s 1 2 3 - 1 8 2 f . I , S e c tio n I I . M a rin e G eology o f th e S o u th e rn C a l i f o r n i a M ain lan d S h e l f , 32 p a g e s , 68 f i g u r e s , 2 p l a t e s . P a r t I : P h y s i c a l p r o p e r t i e s o f s e d im e n t s , b y S t a n l e y W im b e rle y , pages 1 6 9 -1 9 8 , f i g u r e s 1 - 5 6 ; P a r t I I : -Chemical p r o p e r t i e s o f s e d i m e n t s , b y E l a z a r U ch u p i, p a g e s 1 9 2 -1 9 8 , f i g u r e s 5 7 -6 8 , p l a t e s 1-2. I I , S e c t i o n I . M i c r o - p l a n k t o n over t h e M ainland S h e l f o f S o u th e r n C a l i f o r n i a , March 1957-D ecem ber 1959, by Jo h a n n a M. R e s ig , p a g e s 1 -6 0 , f i g u r e s 1 - 3 5 . I I , S e c t i o n I I . The B e n th ic M a rin e F l o r a of S o u th e rn C a l i f o r n i a , by E. Y a l e Dawson, p ag es 6 1 - 1 8 7 , 1 f i g u r e . I I I , S e c t i o n I . The B e n th ic B io lo g y o f S o u th e rn C a l i f o r n i a , 106 p a g e s , 117 f i g u r e s , 25 p l a t e s . Methods o f sa m p lin g and a n a l y s i s , by G i l b e r t F . J o n e s [ a ] , pages 4 - 1 6 , f i g u r e s 1- 11; S ta n d in g c r o p o f t h e b e n th o s o f s o u t h e r n C a l i f o r n i a , by J . L a u r e n s B a r n a r d [a ] , p ag es 1 7 - 5 6 , f i g u r e s 12-58; V a r i a t i o n i n two b e n t h i c c o m m u n itie s o f th e s o u th e r n C a l i f o r n i a m a in la n d s h e l f , b y G i l b e r t F. J o n e s [ b ] , p a g e s 5 7 - 9 3 , p l a t e s 1 -2 5 ; 60 D. C r u s t a c e a , by J . L a u re n s B a rn a rd [ b ], p a g e s 9 4 -1 0 6 , f i g u r e s 5 9 -1 1 7 . Volume I I I , S e c t i o n I I . The D i s t r i b u t i o n and Abun d an ce o f th e B e n th ic M o llu s c a o f t h e M ain la n d S h e l f o f S o u th e r n C a l i f o r n i a , by G i l b e r t F. J o n e s [ c ] , p a g e s 1 0 9 -1 7 0 , f i g u r e s 1 1 8 -1 7 2 . Volume IV, P o l y c h a e t e F a u n a , 120 p a g e s , 66 f i g u r e s , 2 p l a t e s . A. Q u a n t i t a t i v e a s p e c t s o f t h e p o l y c h a e t e s o f th e m a in la n d s h e l f o f s o u t h e r n C a l i f o r n i a , by O lg a H artm an , p a g e s 1 - 1 0 8 , f i g u r e s 1 -5 8 , p l a t e s I - I I ; B. Cum acea, by R o b e r t R. G iv e n , p a g e s 1 0 9 -1 1 5 ; C. S y s t e m a t i c l i s t o f E c h in o d e r m a ta , by F red C. Z ie s e n h e n n e , p a g e s 1 1 7 -1 2 0 , f i g u r e s 1 -8 . Volume V. B i o l o g i c a l D a ta from a Study o f th e B e n th o s o f t h e S o u th e rn C a l i f o r n i a M ain lan d S h e l f , by O lg a H artm an, J . L a u re n s B a r n a r d , G i l b e r t F. J o n e s , R o b e rt R. G iv en and F re d C. Z i e s e n h e n n e , 850 p a g e s . A p p r o x im a te ly 50 c o p i e s o f t h e f i r s t f o u r volum es o f t h i s r e p o r t w ere r e p r o d u c e d by m u l t i l i t h p r o c e s s and c i r c u l a t e d t o th e a u t h o r s , to members o f t h e S t a t e W ater P o l l u t i o n C o n t r o l B oard and o t h e r i n t e r e s t e d p e r s o n s . A lth o u g h th e r e p o r t i s a m a t t e r o f p u b l i c r e c o r d , i t s l i m i t e d d i s t r i b u t i o n h a s made i t a lm o s t c o m p l e t e l y u n a v a i l a b l e t o th e p u b l i c and t h e s c i e n t i f i c com m unity. A lth o u g h a p p ro v e d i n m a n u s c r i p t fo rm by t h e Con s u l t i n g B oard o f th e S t a t e W a te r P o l l u t i o n C o n t r o l Board p r i o r t o i t s p u b l i c a t i o n , t h e 1961 r e p o r t f o l l o w i n g i t s l i m i t e d p a r a - p u b l i c a t i o n was r e j e c t e d b y th e S t a t e W ater P o l l u t i o n C o n t r o l B oard and i t s Board C o n s u l t a n t s . The 61 A l l a n H ancock F o u n d a tio n a g r e e d to make a r e q u i r e d s u b s t a n t i a l r e v i s i o n (AHF:USC, 1965; I n t r o d u c t i o n ) . D r. L e s l i e A. C ham bers, D i r e c t o r o f th e A l l a n H an co ck F o u n d a tio n , comments on th e r e a s o n s f o r th e r e v i s i o n o f th e 1961 r e p o r t i n h i s ’'L e t t e r of T r a n s m i t t a l " w h ic h f o l l o w s th e F orw ard o f th e 1965 r e p o r t . H is l e t t e r i s a d d r e s s e d t o t h e C a l i f o r n i a S t a t e W ater Q u a l i t y C o n t r o l B o a rd , S a c ra m e n to 14, C a l i f o r n i a . D r. C h a m b e rs’ w ords a r e a s f o l lo w s : The r e p o r t h e r e w i t h s u b m i t t e d t o th e C a l i f o r n i a S t a t e W ater Q u a l i t y C o n t r o l B oard em bodies t h e a c c u m u la te d r e s u l t s o f a f i v e - y e a r s t u d y o f m a r in e e n v i r o n m e n t a l phenomena r e l a t a b l e t o th e p r a c t i c e o f w a s te d i s c h a r g e i n t o t h e c o a s t a l w a t e r s o f f s o u t h e r n C a l i f o r n i a . The e x t e n s i v e f i e l d s u r v e y s , fu n d e d by t h e S t a t e B oard w i t h a u x i l i a r y s u p p o r t from th e U n ite d S t a t e s P u b l i c H e a l t h S e r v i c e , w ere c o m p le te d i n 1961. An i n i t i a l r e p o r t c o n s i s t i n g o f i n d i v i d u a l m a n u s c r i p t s from e a c h o f th e s c i e n t i f i c s t a f f was s u b m i t t e d i n t h a t y e a r . The S t a t e B o a rd , and t h e H ancock F o u n d a t i o n , c o n s i d e r e d t h a t c o m p le te r e o r g a n i z a t i o n and i n t e g r a t i o n o f d a t a fro m i n d e p e n d e n t l y c o n d u c te d b i o l o g i c a l , g e o l o g i c a l , c h e m ic a l, and o c e a n o g r a p h ic p h a s e s o f t h e w ork, and e x t e n s i v e r e w r i t i n g , w ere n e c e s s a r y i n o r d e r t o p r e s e n t t h e c o n c l u s i o n s i n a fo rm m o st u s e f u l to th o s e c o n c e r n e d w i t h p ro b le m s o f w a s te d i s c h a r g e . The r e v i s e d v e r s i o n o f th e 1961 r e p o r t a p p e a r s a s P u b l i c a t i o n No. 27 o f th e S t a t e W ater Q u a l i t y C o n t r o l B o ard u n d e r th e t i t l e "An O c e a n o g ra p h ic and B i o l o g i c a l S u rv e y o f th e S o u th e rn C a l i f o r n i a M a in la n d S h e l f . " I t c o n s i s t s o f two p a r t s ; th e r e p o r t h a s 232 p a g e s , 199 f i g u r e s and 20 t a b l e s ; th e A p p e n d ix -D a ta t o th e r e p o r t c o n s i s t s o f 445 p a g e s o f d a t a s u b d iv i d e d i n t o 9 a p p e n d ix t a b l e s . The 62 r e v i s e d r e p o r t was p r e p a r e d by D r s . R ic h a rd B. T ib b y , O c e a n o g ra p h e r, A l l a n H ancock F o u n d a tio n , U n i v e r s i t y o f S o u th e r n C a l i f o r n i a and R ic h a r d D. Pom eroy, Pomeroy and A s s o c i a t e s , P a s a d e n a , C a l i f o r n i a ; Dr. Pomeroy i s t r a i n e d a s a s a n i t a r y e n g i n e e r . D r. Chambers comments on t h e i r work i n h i s l e t t e r a s f o l l o w s : To a c c o m p lis h t h i s r e v i s i o n , th e D i r e c t o r o f th e F o u n d a tio n r e q u e s t e d D r. R ic h a r d T ib b y t o assume r e s p o n s i b i l i t y . He h a s d e v o te d a s u b s t a n t i a l p o r t i o n o f h i s e n e r g i e s t o th e t a s k f o r a b o u t e i g h t e e n m o n th s. I n th e w ork he h a s b e e n a s s i s t e d a b ly by D r. R ic h a rd D. Pom eroy, e n g i n e e r i n g c o n s u l t a n t to th e F o u n d a tio n . I t i s a p l e a s u r e t o acknow ledge th e c o n t r i b u t i o n o f D rs . T ib b y and Pom eroy, a s w e l l as th e re m a rk a b le c o o p e r a t i o n g iv e n them by th e s e n i o r i n v e s t i g a t o r s r e s p o n s i b l e f o r th e s e v e r a l b lo c k s t u d i e s o r i g i n a l l y c o n d u c te d . The r e v i s e d r e p o r t i s c r e d i t e d o n ly to The A l l a n H ancock F o u n d a tio n , U n i v e r s i t y o f S o u th e rn C a l i f o r n i a (AHF:USC, 1 9 6 5 ). Many s e c t i o n s o f th e r e v i s e d r e p o r t a p p e a r as th e y d id i n t h e o r i g i n a l v e r s i o n ; o th e r p a r t s a re s l i g h t l y a l t e r e d and somewhat r e a r r a n g e d ; some o r i g i n a l ma t e r i a l i s p r e s e n t e d . C r e d i t c i t a t i o n s o f th e o r i g i n a l a u t h o r s a r e l a c k i n g e x c e p t f o r a l i s t i n g o f t h e i r names i n th e A cknow ledgem ents (AHF:USC, 1965, p . 2 8 ) . No c i t a t i o n o f th e 1961 r e p o r t i s made i n th e 1965 v e r s i o n ; i t c a n n o t be fo u n d e i t h e r i n t h e R e f e r e n c e s C i t e d (AHF:USC, 1965, p a g e s 2 2 8 -2 3 1 ) or i n th e Addendum; P u b l i c a t i o n s and R e p o r ts (AHF:USC, 1965, page 232) by c h e c k in g f o r AHF:USC, S t e v e n so n , R. E . , or f o r th e names o f any o f th e a u t h o r s o f th e s e v e r a l s e c t i o n s o f th e 1961 r e p o r t . 63 T h ese two r e p o r t s po se a r a t h e r d i f f i c u l t p ro b le m f o r th e p r e s e n t a u t h o r . The 1965 r e p o r t (AHF:USC, 1965) c o n t a i n i n g t h e o r i g i n a l work o f s e v e r a l a u t h o r s i s q u i t e a v a i l a b l e and c o n t a i n s m ost o f th e m a t e r i a l p r e s e n t e d i n th e e a r l i e r r e p o r t , much o f i t v e r b a t i m i n f a c t , b u t t h e r e i s no way o f i d e n t i f y i n g i n d i v i d u a l i t y o f a u t h o r s h i p . C o r r e c t c i t a t i o n o f th e m a t e r i a l i n c l u d e d i n t h e 1961 r e p o r t ( S t e v e n s o n , 1961) becom es somewhat i n v o l v e d i f t h e o r i g i n a l a u t h o r s a r e t o be g i v e n f u l l and c o m p le te c r e d i t f o r t h e i r w o rk , and i f i n a d d i t i o n , an a v a i l a b l e s o u r c e o f t h i s m a t e r i a l i s c i t e d . The f o ll o w i n g p r o c e d u r e i s f o ll o w e d to d e a l w i t h t h i s p ro b le m : ( 1 ) M a t e r i a l i n c l u d e d i n t h e 1961 r e p o r t and a l s o i n c lu d e d i n t h e r e v i s e d r e p o r t and i n o t h e r s o u r c e s ( s u c h a s p u b l i c a t i o n s and d i s s e r t a t i o n s ) w i l l be c r e d i t e d t o th e o r i g i n a l a u t h o r i n S te v e n s o n , 1961, and an a d d i t i o n a l s o u r c e a n d / o r th e r e v i s e d r e p o r t w i l l a l s o be g i v e n . As an exam p l e , W im b e rle y ’ s p a p e r on s h e l f s e d i m e n t s , w h ich was l a t e r p r e s e n t e d o n ly s l i g h t l y m o d if ie d a s h i s d i s s e r t a t i o n and f i n a l l y i s r e p o r t e d n e a r l y u n ch an g ed i n th e r e v i s e d r e p o r t , w i l l be c i t e d a s f o l l o w s : W im b erle y , i n S t e v e n s o n , 1961; W im b erle y , 1965; and i n AHF:USC, 1965. (2 ) M a t e r i a l i n c l u d e d i n th e 1961 r e p o r t and a l s o i n c lu d e d i n th e r e v i s e d r e p o r t b u t n o t i n o t h e r p u b l i c a t i o n s w i l l be c i t e d a s f o l l o w s : G. J o n e s l b ] , i n S te v e n s o n , 1961; and i n AHF:USC, 1965. 64 ( 3 ) M a t e r i a l i n c l u d e d i n th e 1961 r e p o r t and a l s o i n c lu d e d i n o t h e r s o u r c e s , b u t n o t i n th e r e v i s e d r e p o r t , w i l l be c i t e d a s f o l l o w s : G. J o n e s [ c ] , i n S te v e n s o n , 1 9 6 1 ; G. J o n e s , 1964. (4 ) M a t e r i a l i n c l u d e d i n t h e 1961 r e p o r t and n o t a v a i l a b l e e l s e w h e r e w i l l be c i t e d as f o l l o w s : G. Jo n e s [ b ] , i n S te v e n s o n , 1961. F or a u t h o r s w i t h more th a n one p a p e r i n th e 1961 r e p o r t d e s i g n a t i o n o f th e p a r t i c u l a r p a p e r w i l l be i n d i c a t e d b y p l a c i n g t h e a p p r o p r i a t e a l p h a b e t i c c h a r a c t e r im m e d ia te ly a f t e r th e a u t h o r * s nam e; f o r e x a m p le , G. J o n e s [a], i n S t e v e n s o n , 1961, w o u ld be t h e c o r r e c t c i t a t i o n w here th e "M ethods o f s a m p lin g and a n a l y s i s " p a p e r i s c i t e d . A cknow ledgem ents A p p r e c i a t i o n i s c o r d i a l l y e x te n d e d t o th e c h a irm a n o f my g u id a n c e c o m m itte e , D r. J o h n L. Mohr, whose p o s i t i v e c r i t i c i s m h a s c o n t r i b u t e d im m e a su ra b ly to t h e form o f th e f i n a l r e p o r t . C o m p le tio n o f t h i s d i s s e r t a t i o n h as b e e n f a c i l i t a t e d by t h e o t h e r members o f my g u id a n c e c o m m itte e : D r. J a y M. S a v a g e , D r. R o b e rt M. Chew, D r. R u s s e l L. Zimmer and D r. Donn S. G o r s l i n e . T h is p a p e r i s t h e r e s u l t o f p a r t o f s e v e r a l s t u d i e s c o n d u c te d u n d e r c o n t r a c t w ith th e S t a t e o f C a l i f o r n i a W ater P o l l u t i o n C o n t r o l B o ard and g r a n t s from th e N a t i o n a l S c ie n c e F o u n d a tio n and t h e U n i t e d S t a t e s P u b l i c H e a l t h S e r v i c e f o r 65 r e s e a r c h on th e i n f l u e n c e s o f w a s te d i s c h a r g e on t h e b e n t h i c f a u n a and on n a t u r a l m arin e e n v i r o n m e n t s . The w r i t e r i s e s p e c i a l l y i n d e b t e d t o t h e S t a t e B o a rd , t o th e N a t i o n a l S c i en ce F o u n d a tio n , to C a p ta in A l l a n H ancock, and t o t h e A l l a n H ancock F o u n d a tio n o f th e U n i v e r s i t y o f S o u t h e r n C a l i f o r n i a f o r s u p p o r t , f o r t h e u se o f l a b o r a t o r y f a c i l i t i e s and f o r th e u se o f th e r e s e a r c h v e s s e l , V e le r o I V . The p r e p a r a t i o n o f t h e d a t a f o r e l e c t r o n i c p r o c e s s in g and t h e i n i t i a l p h a s e s o f com puter program m ing w ere s u p p o r t e d by a g r a n t from t h e U. S. P u b l i c H e a l t h S e r v ic e CWP-001 5 8 -0 4 ) t o D r. O r v i l l e L. Bandy, D e p a rtm e n t o f G eo lo g y . The w r i t e r i s f u r t h e r i n d e b t e d t o D r. O lg a H artm an f o r d i r e c t i o n o f t h e b i o l o g i c a l w ork and f o r i d e n t i f i c a t i o n o f th e p o l y c h a e t e s ; t o D r. J . L a u re n s B a rn a rd o f th e U n i t e d S t a t e s N a t i o n a l Museum f o r many o f t h e i d e a s t h a t have g u id e d me i n th e a n a l y s i s o f t h i s m a t e r i a l and f o r h i s d e t e r m i n a t i o n by p l a n i m e t r i c a n a l y s i s o f th e a r e a l e x t e n t o f s h e l f b i o t o p e s and r e g i o n s and f o r h i s i d e n t i f i c a t i o n o f c r u s t a c e a n s ( e x c e p t i n g c u m a c e a n s ); t o D r s . R o b e r t E. S te v e n s o n and R i c h a r d B. T i b b y , D i r e c t o r s o f O f f s h o r e R e s e a r c h a t th e A l l a n Hancock F o u n d a tio n , f o r s u p p l y i n g t h e p h y s i c a l d a t a ; t o Mr. R o b e rt R. G iven f o r i d e n t i f i c a t i o n o f th e cu m acean s; t o C a p t a i n F r e d C. Z ie s e n h e n n e f o r th e i d e n t i f i c a t i o n o f t h e e c h in o d e r m s ; to D r. A. Myra K een o f S t a n f o r d U n i v e r s i t y and Mr. E. P. Chace o f t h e San D iego 66 N a t u r a l H i s t o r y Museum f o r t h e i r a i d i n i d e n t i f i c a t i o n o f c e r t a i n o f th e more d i f f i c u l t s p e c i e s o f m o l l u s k s . I am a l s o i n d e b t e d t o my f r i e n d s and c o l l e a g u e s , Mr. V i c t o r A. G a l l a r d o and Mr. K r i s t i a n F a u c h a ld , f o r t h e i r h e l p f u l d i s c u s s i o n s o f t h e p ro b le m s i n v o l v e d i n t h e a n a l y s i s o f a b e n t h i c m a rin e s u r v e y . The c o m p le tio n o f t h i s r e s e a r c h w ould have b e e n im p o s s i b l e w i t h o u t th e f u l l c o o p e r a t i o n o f th e s t a f f o f th e Computer S c i e n c e s L a b o r a t o r y o f th e U n i v e r s i t y o f S o u th e r n C a l i f o r n i a . T h e i r h e l p p l u s t h e use o f th e f a c i l i t i e s , e s p e c i a l l y th e H o n e y w e ll 800 C o m p u ter, w ere e s s e n t i a l t o s u c c e s s . I w is h t o e s p e c i a l l y t h a n k Mr. L y le K n o w le s, who t a u g h t me FORTRAN IV p ro g ram m in g , and Mr. G a r s t R ee se f o r h e l p i n a d a p t i n g t h e R e c u r r e n t Group A n a l y s i s p ro g ra m t o th e H -800. M iss Sue S o r e n s o n , Mr. L a z io E nglem an and Mr. H al Roach a l s o p r o v id e d program m ing a s s i s t a n c e . T h an k s f o r t h e i r p a t i e n c e and c o o p e r a t i o n i s due t h e s t a f f o f o p e r a t o r s a t CSL who t a u g h t me to r u n t h e c o m p u te r. Mr. N i e l G o d fre y was p a r t i c u l a r l y h e l p f u l when t h e ” b e a s t ,T became t r o u b l e s o m e . The h e l p and c o o p e r a t i o n o f D r. A l f r e d W. E b e li n g and Mr. R ic h a r d I b a r a ( U n i v e r s i t y o f C a l i f o r n i a a t S a n ta B a r b a r a ) and D r. F. Jam es R o h lf ( D e p a rtm e n t o f S t a t i s t i c a l B io lo g y ) and D r. Jo h n K ish p a u g h (D e p a rtm e n t o f E l e c t r i c a l E n g i n e e r i n g , U n i v e r s i t y o f K a n s a s ) made i t p o s s i b l e f o r me to o b t a i n t h e r e s u l t s from t h e NTSYS ( N u m e ric a l Taxonomy 67 S ystem ) p ro g ra m . T hese a n a l y s e s w ere made w i t h th e IBM 7040 a t th e U n i v e r s i t y o f K a n s a s ; Mr. I b a r a and D r. K is h p a u g h p e rfo rm e d t h e t a s k s n e c e s s a r y t o i n p u t th e r u n s to t h e ma c h i n e ; Dr. R o h l f p r o v id e d th e m ach in e ti m e . I w is h t o a c k n ow ledge th e c o n t r i b u t i o n o f D r. E . W. P a g e r (D e p a rtm e n t o f B i o l o g i c a l O c e a n o g ra p h y , S c r i p p s I n s t i t u t e o f O c e a n o g ra p h y ) i n p r o v i d i n g me w i t h th e p ro g ra m d e c k o f h i s R e c u r r e n t G roup A n a l y s i s and h i s w i l l i n g n e s s t o c o n s u l t w i t h me on th e p r o b lem s c o n n e c te d w i t h a d a p t i n g i t t o o ur c o m p u te r. T e c h n i c a l a s s i s t a n c e i n p r e p a r i n g t h e d a t a f o r e l e c t r o n i c d a t a r e d u c t i o n was p r o v id e d by M rs. Renee B e r t o l i n o and M iss K a t h i e B r i t t o n ; th e a s s i s t a n c e o f C h r i s t o p h e r J o n e s and Nancy J o n e s i s a l s o g r a t e f u l l y a c k n o w le d g e d . E s s e n t i a l t o t h i s r e s e a r c h w ere th e e f f o r t s o f t h e many s c i e n t i s t s and crew members who s e r v e d a b o a rd th e R/V V e le r o IY ; w i t h o u t t h e i r e f f o r t s t h i s i n v e s t i g a t i o n w ould n o t hav e b e e n p o s s i b l e . F i n a l l y , I w is h t o t h a n k my w i f e , D r. E l i z a b e t h J . J o n e s , f o r h e r c o n s u l t a t i o n on m a t t e r s s t a t i s t i c a l and r h e t o r i c a l an d f o r a l l o f t h o s e o t h e r t h i n g s a w if e can p r o v i d e . I a s k f o r g i v e n e s s o f th e " l i t t l e p e o p l e " who have b e e n m ost p a t i e n t w i t h t h e G r e a t B a lr o g t h r o u g h a l l o f t h i s . T h is work i s d e d i c a t e d w i t h g r e a t a f f e c t i o n t o M r. B ilb o B a g g in s , E s q . , and h i s nephew , F ro d o B a g g in s , who p r o v id e d some l i g h t i n t h i s t u n n e l o f d a r k n e s s . METHODS The A l l a n H ancock F o u n d a tio n S u rv ey S am p lin g P ro g ram The A l l a n Hancock F o u n d a tio n S u rv e y o f t h e S o u th e r n C a l i f o r n i a n M a in la n d S h e l f was i n i t i a l l y d e s ig n e d a s a p u r e ly d e s c r i p t i v e a n a l y s i s o f th e b i o t a o f th e m a in la n d s h e l f , acco m p an ied b y p a r a l l e l g e o l o g i c and o c e a n o g r a p h i c i n v e s t i g a t i o n s . S am p lin g b e g a n on a s y s t e m a t i c random g r i d p a t t e r n . From November 1956 to May 1957, t h e p ro g ra m re m a in e d a g e n e r a l e n v i r o n m e n t a l s t u d y . T hen, a t t h e d i r e c t i o n o f th e R e s e a r c h C o n s u l t i n g B oard o f th e S t a t e W ater P o l l u t i o n C o n t r o l B o a rd , t h e s a m p lin g p ro g ra m was changed t o a r e p l i c a t i n g sa m p le a n a l y s i s . The m a in la n d s h e l f was d i v i d e d i n t o 15 g e o g r a p h i c z o n e s ; t h e s e w ere d e s i g n a t e d " g r e e n , ” " b lu e " and " r e d ” z o n e s a s f o l l o w s : ( 1 ) ” g r e e n ” z o n e s w e re r e g i o n s where w a s te d i s c h a r g e s w ere n o t a f f e c t i n g th e e n v iro n m e n t and p r e s u m a b ly w ould n o t do so i n t h e fo re s e e a b le fu tu r e , (2 ) " b l u e ” z o n e s w ere r e g i o n s w h ere w a s te d i s c h a r g e s were n o t a f f e c t i n g th e e n v ir o n m e n t, b u t m ig h t do so i n th e n e a r f u t u r e , and ( 3 ) " r e d " z o n e s w ere r e g i o n s w here w a s t e d i s c h a r g e s w ere p r e s u m a b ly i n f l u e n c i n g th e e n v ir o n m e n t 68 69 (H artm an and B a r n a r d , 1957; S te v e n s o n , i n S te v e n s o n , 1 9 6 1 , P r e f a c e ) . The s a m p lin g l o c a t i o n s w i t h i n e ach zone w ere a r ra n g e d i n t r a n s e c t s a p p r o x i m a t e l y n o r m a l to t h e c o a s t l i n e ; e a c h t r a n s e c t c o n t a i n e d fro m t h r e e t o s i x s t a t i o n s , e a c h t o be o c c u p ie d two or more t i m e s a y e a r . T h i s m o d if ie d s a m p lin g p ro g ra m was i n t e n d e d to f a c i l i t a t e th e i n v e s t i g a t i o n o f two p r o b le m s a d d i t i o n a l t o th e p u r e l y d e s c r i p t i v e o b j e c t i v e t h a t h ad s e r v e d a s the u n d e r l y in g m o tiv e f o r th e d e s i g n o f th e o r i g i n a l s a m p lin g p ro g ra m . For now, an e f f o r t was t o be made t o a s s e s s t h e e f f e c t s o f w a s te d i s c h a r g e i n th e m a rin e e n v ir o n m e n t t h r o u g h th e com p a r i s o n o f c o n d i t i o n s w i t h i n th e t h r e e ty p e s o f z o n e s. F u r t h e r , i t was hop ed t h a t t h e p e r i o d i c r e s a m p l i n g a t s t a t i o n s e s t a b l i s h e d a s a p a r t o f t h i s p ro g ra m w ou ld s e r v e a s a m easu re o f s e a s o n a l v a r i a t i o n of t h e b e n t h i c i n v e r t e b r a t e p o p u l a t i o n s . T h is i n f o r m a t i o n c o u ld t h e n be ta k e n i n t o a c c o u n t when a t t e m p t i n g t o d e te r m in e t h e v a r i a t i o n c a u se d by p o l l u t i o n a l o n e . U n f o r t u n a t e l y , th e sa m p lin g p ro g ra m d i d n o t a c h i e v e th e d e s i r e d r e s u l t s . The p r im a r y r e a s o n f o r t h e f a i l u r e was th e p o o r d e s i g n o f t h e s a m p lin g p r o g ra m . The z o n e s w e re d e l i n e a t e d w i t h o u t due r e g a r d f o r s u c h s i g n i f i c a n t e n v i r o n m e n ta l d i f f e r e n c e s a s g e n e r a l to p o g r a p h y and s u b s t r a t e c h a r a c t e r . The n a t u r a l d i f f e r e n c e s b e tw e e n (and a l s o w i t h i n , f o r t h a t m a t t e r ! ) m o st o f t h e zo n es w e r e f a r g r e a t e r t h a n any d i f f e r e n c e s t h a t m ig h t be in d u c e d b y th e r a t h e r l o c a l i z e d i n f l u e n c e o f m a n - i n i t i a t e d w a s te d i s c h a r g e o p e r a t i o n s . A ls o , t h e a r r a n g e m e n t o f s t a t i o n t r a n s e c t s was such t h a t c r i t i c a l e v a l u a t i o n o f t h e e n v ir o n m e n t i n th e im m e d ia te a r e a o f sew er o u t f a l l s w as n o t p o s s i b l e . The a t t e m p t to i n v e s t i g a t e s e a s o n a l i t y f a i l e d b e c a u s e t h e l e v e l o f n a v i g a t i o n a l a c c u r a c y a t t a i n a b l e by th e r e s e a r c h v e s s e l w i t h s t a n d a r d m odern a i d s was s t i l l to o c o a r s e f o r p r e c i s e r e s a m p lin g o p e r a t i o n s ; o f t e n a t t e m p t s to re o c c u p y a s t a t i o n w ere s u f f i c i e n t l y i n a c c u r a t e t h a t t h e se co n d sam p le a p p e a r e d t o r e p r e s e n t a com m unity d i s t i n c t fro m th e o r i g i n a l . T h is s a m p lin g p l a n was t h u s ab a n d o n e d , and a s t r a t i f i e d s a m p lin g p ro g ra m was i n s t i t u t e d (G. J o n e s [ a ] , i n S t e v e n s o n , 1 9 6 1 ). F o r t h i s a n a l y s i s , th e s h e l f was d i v i d e d i n t o e i g h t g e o g r a p h i c d i v i s i o n s s e l e c t e d , a s much a s p o s s i b l e , on th e b a s i s o f n a t u r a l d i f f e r e n c e s i n s u c h f a c t o r s a s o r i e n t a t i o n , g e n e r a l s h a p e , s e d im e n t c h a r a c t e r , to p o g ra p h y and r e l a t i v e d e p t h . S u b m arin e c a n y o n s o r p r o m in e n t h e a d l a n d s w e re u sed t o d e l i m i t t h e s e a r e a s . The g e o g r a p h ic f e a t u r e s s e l e c t e d a s b o u n d a r i e s do n o t n e c e s s a r i l y fo rm b i o l o g i c a l b a r r i e r s , b u t do r e p r e s e n t m a r k e rs by w h ich t h e s h e l f may be c o n v e n i e n t l y d i v i d e d . The m a in la n d s h e l f d i v i s i o n s a s i l l u s t r a t e d i n F ig u r e 9 ( a f t e r AHF:USC, 1965, F i g . 1 .2 0 ) a r e t h e f o l lo w in g : A rea I , th e P o i n t C o n c e p tio n s h e l f , P o i n t C o n c e p t i o n t o S a n ta B a r b a r a P o i n t ; 71 A re a I I , t h e S a n t a B a r b a r a s h e l f , S a n t a B a r b a r a P o i n t t o Hueneme s u b m a rin e can y o n ( s o m e tim e s s u b d iv i d e d a t L as P i t a s P o i n t i n t o s u b - a r e a I l a , w e s t e r n , and s u b - a r e a l i b , e a s t e r n ) ; A re a I I I , t h e Mugu s h e l f , Hueneme s u b m a rin e canyon t o P o i n t Dume; A re a IV, t h e S a n ta M onica Bay s h e l f , P o i n t Dume t o Redondo s u b m a rin e c a n y o n ; A re a V, t h e P a l o s V e rd e s s h e l f , Redondo su b m a rin e canyon t o P o i n t F e rm in ; A re a V I, t h e San P e d ro Bay s h e l f , P o i n t F erm in to N ew port su b m a rin e c an y o n ; A re a V I I , t h e N e w p o rt--L a J o l l a s h e l f , N ew port s u b m a rin e c a n y o n t o La J o l l a s u b m a rin e canyon (s o m e tim e s s u b d i v i d e d i n t o t h r e e s u b - a r e a s w i t h d i v i s i o n s a t Dana P o i n t and C a r l s b a d ) ; A re a V I I I , t h e San D iego s h e l f , La J o l l a su b m a rin e canyon t o C oronado s u b m a rin e can y o n ( o f f t h e M exican b o r d e r ) (s o m e tim e s s u b d i v i d e d a t P o i n t Loma i n t o two s u b - a r e a s , V i l l a , n o r t h e r n , and V U I b , s o u t h e r n ) ( 6 . J o n e s [ a ] , i n S t e v e n s o n , 1961; G. J o n e s [ c ] , i n S t e v e n s o n , 1961, F i g . 118; G. J o n e s , 1964, F i g . 1; G. J o n e s and B a r n a r d , 1963, F i g . 2 ) . The " C h a r t o f A r e a s , " F i g u r e 1 .2 0 (AHF:USC, 1965) a s o r i g i n a l l y p u b l i s h e d i s i n c o r r e c t in one p a r t i c u l a r ; th e l i n e i n d i c a t i n g t h e b o u n d a ry b e tw e e n A re a I and A re a I I i s p la c e d a t Las P i t a s P o i n t r a t h e r t h a n a t S a n ta B a r b a r a P o i n t . Figure 9 A Map o f th e M a in la n d S h e l f o f S o u th e r n C a l i f o r n i a Showing t h e E i g h t G e o g ra p h ic D i v i s i o n s Cor A r e a s ) . 72 SANTA X-ONTECJTO BARBARA V > ------ PT. s ' LAS PITAS . P I - VENTURA GAVKJTA AREA II AREA I PT HUENEME P T . lONCEPTII 9Q M . MUGU CANYON. DUME \ CANYON DANA' P I ^ NEWPORT OCEANSIDE 9 0 M - SANTA MONICA NEW PORT C A N Y O N CARLSBAD CANYON SAN AREA EC , - - f \ PALOS ; 1 I VERDES. / 7 ; f e r ./R E D O N BO-..................... .... CANTON AREA ST LA JC CAN' V S A N D E G O ' DUME CANYON PT. LOMA AREA3ZE Figure 9 I 74 The same t y p e o f e r r o r i s to b e seen i n t h e i l l u s t r a t i o n o f t h e s h e l f s u b d i v i s i o n s p r e s e n t e d by G. J o n e s and B a rn a rd (1 9 6 3 , F i g . 2 ) ; i n t h e i r f i g u r e th e b o u n d a r y b e tw e e n A reas 4 and 5 i s s h i f t e d s l i g h t l y t o th e s o u t h o f i t s p r o p e r l o c a t i o n . A s im p le p l a n i m e t r i c m ethod ( B a r n a r d [ a ] , i n S te v e n s o n , 1961; B a rn a rd and J o n e s , 1960; G. J o n e s [ a ] , i n S t e v e n s o n , 1961) w as em ployed t o d e t e r m in e t h e a r e a l e x t e n t o f t h e b o tto m i n c l u d e d w i t h i n e a c h s h e l f segm ent and w i t h i n each d e p t h c l a s s . The r e s u l t s o f t h i s a n a l y s i s a r e p r e s e n t e d i n T a b le 1 ( a f t e r B a r n a r d [ a ] , i n S te v e n s o n , 1961, T a b le 3 ). The s i z e o f e a c h A r e a -D e p th s u b f i l e i s g i v e n i n s q u a r e n a u t i c a l m i l e s ; th e r e l a t i v e s i z e o f each s u b f i l e i s i n d i c a t e d a s a p e r c e n t a g e o f t h e t o t a l . These d a t a s e r v e d a s th e b a s i s f o r t h e d e v e lo p m e n t o f th e s t r a t i f i e d s a m p lin g sy stem u s e d f o r much o f t h e a n a l y s i s o f th e s h e l f m a c ro fa u n a by t h e b i o l o g i s t s o f t h e H ancock M ain lan d S h e l f S u rv e y . In i t s c o n s t r u c t i o n e x i s t i n g s a m p le s w ere a s s i g n e d to r e p r e s e n t e a c h A re a -D e p th s u b f i l e on a p r o p o r t i o n a l b a s i s . Where n e c e s s a r y , a d d i t i o n a l s a m p le s w ere c o l l e c t e d to c o m p le te t h e p a t t e r n (G. J o n e s , 1 9 6 4 ). The o r i g i n a l s t r a t i f i e d sam ple c o m p r is e d 176 OPB s a m p le s ; t h e s e a re l i s t e d by V e le r o IY S t a t i o n Number in A p p e n d ix T a b l e A - l . The a r ra n g e m e n t o f t h e s e s a m p lin g l o c a t i o n s f o rm s an i r r e g u l a r p a t t e r n t h a t e n c o m p a s s e s th e d e p t h s o f 5 t o 100 f a th o m s ( 9 . 1 t o 1 8 2 .8 m) b e tw e e n TABLE 1. A rea o f D epth C l a s s e s f o r th e E ig h t G e o g ra p h ic A r e a s - - t h e B a s is f o r th e S t r a t i f i e d Sam pling System D eveloped by J . L a u re n s B a rn a rd ( a f t e r B a rn a rd [ a ] , i n S te v e n s o n , 1961, T a b le 3 ) . The f o u r num bers o f e ach e n t r y a r e (1 ) t h e s i z e o f th e d e p th c l a s s i n n a u t i c a l s q u a re m i l e s , (2 ) th e p e r c e n t o f t h i s a r e a c a l c u l a t e d a g a i n s t th e t o t a l a r e a o f t h e m a in la n d s h e l f , (3) th e number o f s t a t i o n s u sed t o r e p r e s e n t t h i s u n i t , and (4 ) t h e t h e o r e t i c a l number o f s t a t i o n s t h a t s h o u ld be employed to r e p r e s e n t th e u n i t o f a r e a on a p e r c e n ta g e b a s i s . D e p th C l a s s e s i n Fathom s A re a s 0 -1 0 11-20 21-30 31-40 41-50 51-100 T o t a l A rea o f S h e l f D i v i s i o n s I 2 2 .9 ;2 .2 % 4 ( 3 . 8 ) 1 6 .7 ;1 .6 % 3 ( 2 .8 ) 2 1 .4 ;2 .0 % 4 ( 3 . 5 ) 3 7 .6 ;3 .5 % 6 ( 6 . 2 ) 2 7 .0 ;2 .5 % 4 ( 4 .5 ) 2 3 .0 ;2 .2 % 2 ( 3 .8 ) 1 4 8 .6 ;1 3 .9 % 2 3 ( 2 4 .4 ) I I 4 4 .8 ;4 .2 % 7 ( 7 .5 ) 4 3 .9 ;4 .1 % 1 1 ( 7 .3 ) 4 1 .3 ;3 .9 % 7 ( 7 .4 ) 2 8 .8 ;2 .7 % 5 ( 4 .8 ) 2 8 .0 ;2 .6 % 5 ( 4 .6 ) 4 6 .5 ;4 .4 % 6 ( 7 .7 ) 2 5 6 .7 ;2 4 .2 % 4 1 ( 4 2 .6 ) I I I 1 3 .1 ;1 .2 % 2 ( 2 . 2 ) 1 0 .8 ;1 .0 % 2 ( 1 . 8 ) 9 .5 ;0 .9 % 2 ( 1 .6 ) 8 .1 ;0 .8 % 1 ( 1 .3 ) 5 .6 ;0 .5 % 1 ( 0 .9 ) 9 .8 ;0 .9 % 2 ( 1 .6 ) 5 6 .9 ;5 .3 % 1 0 ( 9 .4 ) IV 2 6 .7 ;2 .5 % 4 ( 4 .4 ) 2 2 .0 ;2 .1 % 4 ( 3 . 7 ) 2 8 .7 ;2 .7 % 5 ( 4 .8 ) 2 3 .3 ;2 .2 % 4 ( 3 . 9 ) 1 6 .0 ;1 .5 % 3 ( 2 .7 ) 1 8 .5 ;1 .7 % 3 ( 3 .1 ) 1 3 5 .2 ;1 2 .7 % 2 3 ( 2 2 .4 ) V 5 .6 ;0 .5 % 1 ( 0 .9 ) 5 .0 ;0 .5 % 1 ( 0 .8 ) 0 1 1 .3 ;1 .1 % 1 ( 1 .9 ) 1 3 .1 ;0 .3 % 0 ( 0 .5 ) 2 5 .0 ;2 .3 % 4 ( 4 .0 ) VI 3 0 .4 ;2 .9 % 5 ( 5 .0 ) 5 1 .6 ;4 .9 % 8 ( 8 .5 ) 2 5 .4 ;2 .5 % 4 ( 4 .4 ) 1 1 5 . 5 ; 1 . 5% 2 ( 2 .6 ) 1 0 .4 ;1 .0 % 1 ( 1 . 7 ) 1 3 3 .3 ;1 2 .5 % 2 1 ( 2 2 .0 ) - aJ 3 • h c r ai < u p S P P P < u o O >. u cm pi Pi < u •H 3 P D * P < D O P C O P P Pi Q J P Pi >* O O U Pi ai co 3 O a 1 O a ; p U P u o ■ p a p i p! < u o E •H 3 cr ■ a < u c u p co P POLYCHAETES: (8 ) (6 ) (4) (5 ) (4 ) (6) (3 ) (4 ) (6 ) P r io n o s p i o p i n n a t a +++ +++ +++ +++ +++ ++ + + + +++ +++ P r io n o s p i o m alm greni + • 1 — h +++ +++ ++ +++ ++ + ++ +++ +++ P e c t i n a r i a c a l i f o r n i e n s i s ++ +++ ++ +++ +++ ++ + + + +++ +++ P h o lo e g l a b r a +++ ++ ++ +++ +++ ++ + + + +++ +++ P a r a o n i s g r a c i l i s ++ ++ +++ ++ ++ ++ + + + +++ +++ S p io p h a n e s m i s s i o n e n s i s + + +++ ++ ++ +++ ++ + + + +++ + 116 + + *+ o 8 > a o p t o in f D o 3 r+ H | u . 3 t o p 3 > O 3* t o P* P O P* t+ p a n a •c 3 t o o g f D t o p a zj p p 1 0 w t / 1 o 3 » I P* ■a p f t p O • 3 3 3 3 a o W f D P- b N a 3 o P> p + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + CO 00 00 + + + + + + + + + + + + + '~ N + + + + M + + + + + + + + + DO + + 3 O t - < o in K i ~ 3 3 P c+ p 3* 3 * • < fD 3 P Q o * n 3 p* 3 p ; 3 fD 3 o 5 P* 3 P t o tri 3 p t o r > H fD 3 o r+ w 1 - 4 o p- p* fD t/1 P- p t o o t o to •3 to < — » p* H h p* fD o O r+ O o P * o 3 P to to P 3 P r+ to r+ r+ N P o fD P * fD 3 p ! V -/ 3 o * • to 3 P» C fQ to p r+ P to + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 00 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + pj P cr p* fD U t in 73 C' fD O * ts 03 -P p r* bO -rl < 1 3 ■ r * « s o i n r» P i p i p - p p d p < 1 3 P ■ d rs d P 03 d e 03 03 u > •H > . O >* d > . d d o Q o o o o p o o >> U P o d d txo d o d d d o P ■ h d O 0) d aj d 03 03 03 03 •rl d C L ) d d d •h d r o d 6 d T3 W d p p a 1 •h a 1 p a 1 O o 1 •ri o ’ d d b o d rH < 1 3 T3 03 P 03 O 0) *0 03 d < U p o •H p 03 P O P d p 03 P CO T3 O O C/3 P S P C /3 P O P C /3 P ( 4 ) ( 5 ) ( 4 ) ( 6 ) ( 3 ) ( 4 ) ( 6 ) +++ +++ 4"4- 4- 4* +++ +++ ++ 4*4* 4-4* 4* +++ +++ ++ H * + + + 4*4-4- 4- + ++ + + + + + 4-4- 4*4- C2) + + + + + + 4- (3 ) + + + + + + + + + + (2 ) (2 ) (2 ) + + + + + + + + + +++ + + + 4-4- + + + +++ +++ + + + ++ ++ + ++ +++ +++ +++ ++ +++ ++ +++ ++ +++ p* oo 6TI 0 1 O W O H l-»* P* fD H P OQ K* P O p P nd a 1 P 1 D . i— 1 fD fD fes i- j H 01 P o 3 3 fD H i £1 H* r+ pi fD H* P H H c+ H H C/1 O l O Pi H O r+ r ■a 4 01 a a fD (D P fD K* fD Pi o Q o H Pi 01 P ■ > H - o n> p* 01 fD p cd P > p 01 c+ p . M p P • tn P p W (-» J_A a o P CO P pi sj o CO fD 3 c o o H i O P * H - 1 01 ► P p pi H fD o + + + /— I CO • + + + 00 ■ P * O l + + H i • CO O O ' H vO CO o + ✓ — \ + S ~ \ vO H « CO + O ' U i O l + a • CO f t CO cm H fD CO o + + + -''N fD c n + + + ■ p> 01 H O ' + + * CO o U l H i H i CO o + + + / " I H H • + O l fD CO O ' + I— ' fD « CO a o o 3 + + + + + + p> /"S + + z 1 H + + P CO + O ' H + c+ P* fD + + + O + + + CO • + O H* H + + + /~ s n> + + + -P* <J + + + V -' fD H O H i + + + s~\ <5 C /l P p H o ' H* Hi P H O ' H * H fD fD 01 01 A re a , d e n s i t y D ep th , d e n s i t y + + O Sand C o n t e n t , d e n s i t y O r g a n ic N i t r o g e n C o n t e n t , d e n s i t y S i l t C o n t e n t , f r e q u e n c y M edian D ia m e te r , f r e q u e n c y S o r t i n g C o e f f . , f r e q u e n c y CaCOg C o n t e n t , f r e q u e n c y S ed im e n t °C, f r e q u e n c y 120 Sample volum e w as m easured f o r 169 o f th e 176 sam p l e s c o n s t i t u t i n g th e s t r a t i f i e d s a m p le s e t ; m easu red v o l umes ra n g e d fro m 1 .7 to 9 7 .9 l i t e r s (mean, 3 2 . 0 l i t e r s ) . The f o llo w in g s i x s u b f i l e s were d e l i n e a t e d w i t h i n t h i s r a n g e : l e s s t h a n 7 .1 0 l i t e r s (18 s a m p l e s ) , 7 . 1 1 to 1 4 .1 0 l i t e r s (19 s a m p l e s ) , 1 4 .1 1 to 2 1 .2 0 l i t e r s ( 2 8 s a m p l e s ) , 2 1 .2 1 to 2 8 .3 0 l i t e r s (1 8 s a m p l e s ) , 2 8 .3 1 t o 4 2 .4 0 l i t e r s (3 4 s a m p le s ) , an d g r e a t e r t h a n 4 2 . 4 0 l i t e r s (5 1 s a m p l e s ) . The r e s u l t s o f s p e c i e s r a n k i n g o f t h e 100 t o p - r a n k e d s p e c i e s i n t h e 1 7 6 -sa m p le s e t w i t h i n t h e s e s u b f i l e s r e v e a l t h a t only- one c a t e g o r y , l e s s th a n 7 .1 0 l i t e r s , f a i l e d t o c o n t a i n a l l 100 s p e c i e s , and i t c o n t a i n e d 99 o f t h e 100. The number o f s p e c i e s c o l l e c t e d i n 40 p e r c e n t or m ore o f th e s a m p le s in e a c h o f t h e s i x sam p le volume s u b f i l e s i n o rd e r fro m lo w e s t (< 7 .1 l i t e r s ) t o h i g h e s t ( > 4 2 .4 l i t e r s ) a re a s f o l l o w s : 4 4 , 44, 5 5 , 37, 6 1 , and 49. The mean o f t h e s e n u m b e rs i s 4 8 .3 . T h i s mean v a l u e was u s e d as t h e b a s i s f o r a n u l l h y p o t h e s i s t h a t th e v a r i a t i o n among s u b f i l e s c o u ld be e x p e c te d by c h a n c e . The v a l u e o f X2 was c a l c u l a t e d a s 7 . 7 3 ; t h i s v a lu e i s n o t s i g n i f i c a n t a t t h e 0 . 0 5 l e v e l (X3 = 1 1 .0 7 ) and t h e n u l l h y p o t h e s i s i s s u p p o r t e d : th e o b s e rv e d v a r i a t i o n i n th e number o f s p e c i e s w i t h f r e q u e n c i e s o f 40 p e r c e n t or more i n t h i s g r o u p of s u b f i l e s c a n b e e x p l a i n e d on the b a s i s o f c h a n c e a l o n e and n e e d n o t be a t t r i b u t e d t o s a m p lin g v a r i a t i o n . 121 A s i m i l a r r a n k i n g a n a l y s i s b a s e d on p o p u l a t i o n d e n s i t y (mean number o f i n d i v i d u a l s p e r s q u a r e m e te r ) o r d e re d t h e same 100 s p e c i e s w i t h i n e a c h s u b f i l e . On th e b a s i s o f t h i s a n a l y s i s a K e n d a l l C o e f f i c i e n t o f C oncordance was c a l c u l a t e d , y i e l d i n g a W v a lu e o f 0 .6 8 5 . The X2 d e r i v e d from t h i s W i s 4 0 6 , w e l l above th e v a l u e ( 1 3 3 .3 ) a t th e 0 .0 1 l e v e l o f s i g n i f i c a n c e . A s i g n i f i c a n t d e g r e e o f ag re e m e n t t h u s e x i s t s among t h e s i x s e t s o f s p e c i e s r a n k i n g s by volume s u b f i l e s . The m a g n itu d e o f W s u g g e s t s t h a t t h e s a m p lin g te c h n iq u e (OPB) em ployed to c o l l e c t t h e s e sa m p les i s l e s s i m p o r t a n t a f a c t o r i n i n f l u e n c i n g th e r e s u l t s th a n m ig h t be d ed u ced fro m th e r e l a t i v e l y w id e ra n g e o f sam ple v o lu m es. R anking b y B e n th ic A s s o c i a t i o n s B ecau se e a c h b e n t h i c sam ple was a s s ig n e d an a s s o c i a t i o n d e s i g n a t i o n by th e AHF s u rv e y b i o l o g i s t s (A p p en d ix T a b le A - 3 ) , th e 1 7 6 -sa m p le s e t i s d i v i d e d i n t o a s e r i e s o f g ro u p s r e p r e s e n t i n g th e p r e v i o u s l y d e s c r i b e d s h e l f m acro - f a u n a l a s s o c i a t i o n s . These sam ple g r o u p s w ere t r e a t e d as . _ f. s u b f i l e s i n th e p r e s e n t i n v e s t i g a t i o n , and t h e 100 t o p - ra n k e d s p e c i e s by f r e q u e n c y o f o c c u r r e n c e o f th e 1 7 6 -sam p le s e t were ra n k e d w i t h i n e a c h a s s o c i a t i o n s u b f i l e . T hese s u b f i l e s a r e as f o l l o w s : th e A m phiodia a s s o c i a t i o n (38 sam p l e s ) , th e A m p h io d ia- C a r d i t a a s s o c i a t i o n (23 s a m p l e s ) , th e A m p h io d ia- O nuphis a s s o c i a t i o n (5 s a m p l e s ) , th e A m phioplus h e x a c a n th u s a s s o c i a t i o n (10 s a m p l e s ) , th e C h l o e i a - P e c t i n a r i a 122 a s s o c i a t i o n (5 s a m p l e s ) , th e N o t h r i a - T e l l i n a a s s o c i a t i o n (35 s a m p l e s ) , th e D i o p a t r a a s s o c i a t i o n (1 1 s a m p l e s ) , th e L i s t r i o l o b u s a s s o c i a t i o n (1 0 s a m p l e s ) , and th e N o t h r i a - S p io p h a n e s a s s o c i a t i o n (7 s a m p l e s ) . M inor a s s o c i a t i o n s , t h o s e r e p r e s e n t e d by f e w e r t h a n f i v e s a m p le s , w ere n o t co n s i d e r e d i n t h i s a n a l y s i s . The r e s u l t s o f t h e s p e c i e s r a n k i n g s by f r e q u e n c y o f o c c u r r e n c e i n e a c h s u b f i l e f o r th e 100 t o p - r a n k e d s p e c i e s i n th e 1 7 6 -sa m p le s e t w ere exam ined and a b s t r a c t e d ; th e 33 s p e c i e s o c c u r r i n g i n 40 p e r c e n t o r more o f th e s a m p le s i n s i x o r more of t h e n i n e a s s o c i a t i o n s a r e l i s t e d i n T a b le 6 . W ith in e a c h c a t e g o r y s p e c i e s a r e a r r a n g e d fro m h i g h e s t t o lo w e s t by t h e mean o f th e f r e q u e n c i e s w i t h i n e a c h a s s o c i a t i o n . S p e c i e s common to t h i s l i s t and T a b le 4 a r e i d e n t i f i e d by an a s t e r i s k . Four s p e c i e s , " n e ra e rte a n s u n k n o w n ,” P r i o n o s p i o p i n n a t a , A m p h io d ia u r t i c a , and A m p h ip h o lis s q u a m a ta , o c c u r above t h e minimum l e v e l i n a l l n i n e a s s o c i a t i o n s ; t h e s e f o u r s p e c i e s a r e ra n k e d f i r s t , s e c o n d , t h i r d and f i f t h i n T a b le 4 . S i x s p e c i e s o c c u r i n e i g h t o f t h e n i n e a s s o c i a t i o n s , and f o u r o f t h e s e a r e l i s t e d i n T a b le 4; t e n s p e c i e s o c c u r i n s e v e n o f th e n in e a s s o c i a t i o n s , and f i v e o f t h e s e a r e l i s t e d i n T a b le 4; 15 s p e c i e s o c c u r i n s i x o f t h e n in e a s s o c i a t i o n s , and t e n o f t h e s e a r e common t o T a b le 4 . Table 6. S p e c ie s R an k in g s by A s s o c i a t i o n s . The 33 s p e c i e s o f th e 100 t o p - r a n k e d s p e c i e s i n th e 17 6 -sam p le s e t o c c u r r i n g i n 40% or more o f th e sam p les i n s i x or more o f th e n in e a s s o c i a t i o n s u b f i l e s . The S pearm an’ s r s v a lu e c a l c u l a t e d on th e com p a r i s o n o f t h e r a n k s o f th e 100 to p - r a n k e d s p e c i e s i n th e 17 6 -sam p le s e t w i t h t h e i r r a n k s i n e a c h a s s o c i a t i o n . O = p r e s e n t i n l e s s th a n 40% o f th e sam p les o f th e s u b f i l e ) . ctS •rl ■ o O •r| X i S S 3 O •rl P ctS •rl O o p w w < ■r| X L P S 3 O i i cti •H ’ O o ■ H X i e < a o rl P ctS rl O o C O t o < (0 3 x i p S 3 ctS o C tS X < u XL to P i— i p j o • H XL e < S 3 o r l P C tS 'H O o to to < ctS S 3 •rl r-l 1—1 (U H i i ctS •H U xi p o S S 3 o ■rl P C t S •rl O O to to < ctS •rl tu 0 1 — I j:3 O 1 I ctS •r| P C tS S 3 •H P O C U PU S 3 o rl P ctS rl U O to t o & ctS p •r| rO u ctS O I I ctS •r| X f o •rl S 3 o •r| P C t S •r| O O to C O < c t S u p ctS S 3 o rl P ctS rl O O •rl Q to < U S 3 c t S A P 0 •rl P. S 3 1 0 o 1 « H I P P O C O C O < ctS •r| S - 4 X p o s ctS rl u o to to < to p x o iH o •rl p to •rl 1 -1 S 3 o •rl P ctS •rl O O to C O < V alue o f r„ 0 .7 0 7 0 .6 5 2 0 .5 9 2 0 .5 2 6 0 .4 7 5 0 .4 5 2 0 .4 0 7 0 .2 2 6 0 .1 5 5 S p e c i e s : n e m e rte a n s unknown* 89% 100% 100% 100% 100% 100% 100% 71% 90% P r io n o s p i o p i n n a t a * 92 100 100 94 100 96 91 43 90 A m phiodia u r t i c a * 100 100 100 86 100 100 64 43 100 A m p h ip h o lis squam ata* 92 80 90 94 60 65 82 .57 50 P r io n o s p i o m alm greni* 92 100 90 92 80 70 91 86 + oo PZT < p > hd i-3 hd f 00 o r+ M 3 3* 3 * fD p o P 3 >3 o P O o H * 3 3 fD fD M h r+ 3 O H * P H 1 O H * ( - * • * d p H * o M * ft X 3 o 3 * a a H i 01 P fD p p 01 O 00 c+ H 3 H P M fD H - O fD o' 3 01 P 01 P H* 01 H 3 O* O 1 01 H 3 X 1 H fD O H 3 3 3 fD P M P P jj. 3 O < * P H* c+ Ol fD H* « + H - P 01 P 3 01 P H i H > * H * * O O 3 H 3 3 3 fD i — 1 H - 3 P fD 0 1 r+ 3 H * P 01 01 * H* * 01 * h - 1 o 0 0 vO O O l O ' - 4 1 O ' • o o o W oo -41 O -41 I — 1 I - 1 O o o O ' o O ' 0 0 O ' 0 0 • o o O o o o o o O ' O l t o o O i \D 0 0 -41 O ' -41 O l 00 « o o O o o O o o O l VO CO o O l + O l -P -£■ O ' -41 • •P - o VO - o O ' -41 0 0 O l CO O ' M H* H - o • p O 00 O O ' O ' O 00 • O O o O o o O o -41 O l o <1 NO - n vO 00 O ' O l -41 • 00 H* 00 O ' - 1 O l - 1 00 - p O l CO o 0 0 + O ' •P = . O l O l • O l C O : -P O l O l O l o -41 o + + + + + • CO CO O ' o -'J O ' + vO ■ -P O l O l - p • o o o o o o o L a La A m phiodia A s s o c i a t i o n Amphi od i a - - O nuphis A s s o c i a t i o n A m p h io p lu s h e x a c a n th u s A s s o c i a t i o n N o t h r i a - ~ T e l l i n a A s s o c i a t i o n P e c t i n a r i a - - C h l o e i a A s s o c i a t i o n A m phi o d i a - - Card i t a A s s o c i a t i o n D i o p a t r a A s s o c i a t i o n N o t h r i a - - S p i o p h an es A s s o c i a t i o n Listriolobus Association Table 6 ( C o n t .) o i~ 3 hd h3 > Q o X 3 fD H * fD X H1 in P p 3 3 M H - O H - H * r+ fD 3 fD O H - H i H * 3* O1 H * •o c+ c+ P O H * fD X m 3* H- O •d P H » P P fD Q. o 3* H > < i I-1 H- a P O H - in 3 H * P l/l I/i i-i o. d) to P 3 fD fD P 3 P 3 in o H i 1 — 1 3 3 o 3 D* C T Q l - i in tfl o1 H * 3 fD P r+ t + H d o 3 r+ H i p O P H ‘ H - O l-i O X - p 3 H h fD 3 H* X p l-i 3 3 3 t+ O H - O p 3 c+ C O P -J oo O ' - P 00 00 o o + + 0 0 O ' o o vO vQ O n O ' -a o o o ^ U l J i . f i O ' -J CO 0 0 O l -4] OJ H* La O' oo o co co o o o o o o 4 ^ - L a C » O - 4 O ' O O O O O o L a CO -p o 4 ^ . O ' O ' O ' - f C O O J v O O J -P o L a O ' La L a + -41 -4 1 O J -P OJ 00 O ' o o La - P i + + -J -J -a oo 4^ oo + -P i O J O' + La -P -P oo o o o o o < p M 3 f D O H-i in -41 o - 4 ] O ' Ol CO Ol V O C O La C O O ' ■ P i - 4 1 Ol p La C O - 4 1 o w C O O ' M :O l O l A m p h io d ia A s s o c i a t i o n Amphi o d i a - - O n u p h is A s s o c i a t i o n A m p h io p lu s h e x a c a n t h u s A s so c i a t i o n N o t h r i a - - T e l l i n a A s s o c i a t i o n P e c t i n a r i a - - C h l o e i a A s s o c i a t i o n Amphi o d i a — C a r d i t a A s s o c i a t ion D i o p a t r a A s s o c i a t i o n N o t h r i a - - S p io p h a n e s A s s o c i a t i o n Listriolobus Association Table 6 ( C o n t.) o 3 a > X W a > * T l p i fD o 3 pi ri- ri* X ff Oi 3 in Td fD * < ! ri r i £ pi C /1 fD ri1 ri o ff ff ri- £ ri* O 3 fD o O £ O ri ri- to P i ri •3 3 to a P i in O (fl ff to ri- fD o O 3 ri- in t o in o p i M ri- O a id p i O in P I pi e ra • £ 3 n t d ri 3 a ri I — 1 Hi ri- in ff W r i - ri- o O ri fD ff 3 a in in in f f ri ri O p i ri- in ri ri f f * Sj * P i fD o ff ri ri- p ri" M ri * ff to * P I * O 3 era p i ri ff to X - * ff ri ff * X - on + O J O' O' o o v O o o O' O' O J o + + + + + - p = > on - 41 oo M O' -41 -P* o o 921 O' - P ^ 00 O ' oo o o ■ p i O' o o + 00 O J •ff + o 'O + + 0/1 on -I O' ■ff O' o '• O o 00 O' . f f o O' - p i "■I -41 o o 00 vO vO t-» M K M H O' O O O o o o o on on on + o o o + + + .ff v O O' -ff O' C O o o o o ~-J CO 'O vD 0 0 OJ M O ' + + v O o v O o - 4 1 o - 4 1 O O' o < J ff r i * £ I D o H i 0 1 -41 O -4] O ' On D O on v O DO O n DO O' -41 O n •ff on C O .-P i o '■41 to DO O' on cn A m p h io d ia A s s o c i a t i o n Amphi od j a - - O nuphi s A s s o c i a t i o n A m p h io p lu s h e x a c a n t h u s A s s o c i a t i o n N o t h r i a - - T e l i i n a A s s o c i a t i o n P e c t i n a r i a - - C h l o e i a A s s o c i a t T o n A m p h io d ia - - C a r d i t a A s s o c i a t i o n D i o p a t r a A s s o c i a t i o n N o t h r i a — S p io p h a n e s A s s o c i a t i o n fcistriolobus Association Table 6 ( C o n t .) * II o o 3 3 o y r + O H s» D * M f D y H * n > y n > i n i n y i n •o R - y o i n y > r - o ( - * • D . f D y R* O 1 3 f D N R - * fD X T r + '< i n i n > d * + L n 4s> O i - O ■f* O ' O ' o o o - 3 CO CO o o o O ' O l O ' v O -0 v O • R - + -y o o + + + O l O l O l O l O l O l C jJ w AST < ! s » I - * y fD o H i i n O ' O l CO O l v O ( O O l to O ' -R. - 3 O l - R * O l to -R o -o CO CO O ' O l : O l Amphi odia. A s s o c i a t i o n Amphi o d i a - - O nuphis A s s o c i a t i o n A m phioplus h e x a c a n th u s A s s o c i a t i o n N o t h r i a - - T e l l i n a A s s o c i a t i o n P e c t i n a r i a - - C h i d e i a A s s o c i a t io n A m p h io d ria - - C a r d i t a A s s o c i a t i o n D i o p a t r a A s s o c i a t i o n N o t h r i a - - S p io p h a n e s A s s o c i a t i o n Listriolobus Association Table 6 ( C o n t.) 128 The K e n d a ll C o e f f i c i e n t o f C o n c o rd a n c e a n a l y s i s was a p p l i e d t o a s s e s s t h e e f f e c t o f a s s o c i a t i o n a f f i l i a t i o n on t h e s e l e c t e d f a u n a l f r a c t i o n . Mean d e n s i t y , n o t f r e q u e n c y o f o c c u r r e n c e , was u s e d a s t h e b a s i s f o r r a n k i n g t h e s e s p e c i e s a s i t r e d u c e d th e number o f t i e d r a n k s . The v a lu e o f W c a l c u l a t e d f o r th e r a n k i n g s o f t h e 100 s p e c i e s i n t h e n i n e a s s o c i a t i o n s i s 0 . 3 5 9 ; th e X2 v a l u e d e r i v e d fro m t h i s W i s 359, s i g n i f i c a n t a t th e 0 .0 1 l e v e l . The c o n c o rd a n c e b e tw e e n t h e s e n i n e r a n k i n g s i s c o n s i d e r a b l y lo w er t h a n t h a t f o r any o f t h e fo u r p h y s i c a l v a r i a b l e s t e s t e d ( f o r w h ich W = from 0 .5 3 2 t o 0 . 6 3 5 ), b u t i t i s g r e a t e r t h a n t h a t w h ic h w ould be e x p e c t e d t o o c c u r by c h a n c e a l o n e . The a s s o c i a t i o n s u b f i l e r a n k i n g s may be f u r t h e r com p a r e d by d e t e r m i n i n g t h e i r s i m i l a r i t y to some s t a n d a r d l i s t in g o f th e same 100 s p e c i e s . The s t a n d a r d s e l e c t e d was th e o r d e r i n g o f t h e s e s p e c i e s by d e n s i t y f o r a l l 176 s a m p le s . The d e g r e e o f a s s o c i a t i o n b e tw e e n two v a r i a b l e s , i n t h i s c a s e d i f f e r e n t sam ple g r o u p s , may be d e t e r m in e d by S p e a rm a n ’s Rank C o r r e l a t i o n C o e f f i c i e n t ( r o r rh o ) fro m th e r a n k e d s c o r e s o f t h e s e v a r i a b l e s m e a su re d on N i n d i v i d u a l s , th e 100 s p e c i e s ( S i e g e l , 1 9 5 6 ). The v a l u e o f S p e a rm a n ’ s rh o was c a l c u l a t e d f o r e a c h a s s o c i a t i o n s u b f i l e r a n k in g com pared w i t h th e s t a n d a r d r a n k i n g l i s t . T h e se d a t a a r e shown i n T a b le 7 . 129 T a b le 7 . The S p e a rm a n ’ s r_ v a l u e s and t v a l u e s f o r t h e R a n k in g s by A s s o c i a t i o n S u b f i l e s . . i c i a t i o n S u b f i l e r — s t A m ph io d ia 0 .7 0 7 9 .8 9 Amphi o d ia -O n u p h i s 0 .6 5 2 8 .3 0 A m p h ioplus h e x a c a n t h u s 0 .5 9 2 7 .2 7 N o t h r i a - - T e l l i n a 0 .5 2 6 6 .1 1 C h l o e i a - - P e c t i n a r i a 0 .4 7 5 5 .3 1 A m p h i o d i a - - C a r d i t a 0 .4 5 2 4 .9 9 Di o p a t r a 0 .4 0 7 4 .4 1 N o t h r i a — S p io p h a n e s 0 .2 2 6 4 .3 0 - 0 . 0 1 l e v e l -------------------------------------------------- 2 . 6 3 ------- ------------------------- 0 . 0 5 l e v e l -------------------------------------------------- 1 . 9 8 ------- L i s t r i o l o b u s 0 .1 5 5 1 .7 4 130 The s i g n i f i c a n c e o f r u n d e r t h e n u l l h y p o t h e s i s may s be t e s t e d b y a t v a lu e d e f i n e d by t h e f o r m u la For l a r g e s a m p l e s , N e q u a l t o o r g r e a t e r t h a n 10, t i s d i s t r i b u t e d a s S t u d e n t ’ s t_ w i t h d f = N - 2 . The _t v a l u e s a r e l i s t e d w i t h t h e i r c o r r e s p o n d i n g r s v a l u e s i n T a b l e 7. a t e l y a p p a r e n t fro m th e r v a l u e s i n T a b le 7 . T h ese v a l u e s r a n g e fro m 0 . 7 0 7 f o r t h e A m p h io d ia s u b f i l e t o 0 .1 5 5 f o r th e L i s t r i o l o b u s a s s o c i a t i o n . The l a t t e r v a l u e i s n o t s i g n i f i c a n t a t t h e 5 p e r c e n t l e v e l . For two a s s o c i a t i o n s , N o t h r i a - S p io p h a n e s and L i s t r i o l o b u s , r s v a l u e s w ere b e lo w 0 .3 0 0 ( 0 .2 2 6 and 0 .1 5 5 r e s p e c t i v e l y ) . The l a t t e r v a l u e m ig h t be e x p e c t e d by c h a n c e a l o n e . H ow ever, i n my o p i n i o n i t i s more l i k e l y t h a t t h e f a u n a l d i f f e r e n c e s o f t h e s e two a s s o c i a t i o n s , a s com pared t o th e e n t i r e s h e l f by th e r a n k c o r r e l a t i o n a n a l y s i s , a r e d u e to t h e i r d i s t i n c t i v e s e d i m e n t s . T a b l e s 8 and 9 com pare s e d im e n t c h a r a c t e r i s t i c s o f t h e s e two a s s o c i a t i o n s w i t h t h o s e o f t h e s h e l f a s a w h o le . d o m in a te d " a s s o c i a t i o n s , A m p h io d ia , A m p h io d ia - Q n u p h i s , A m p h io p lu s h e x a c a n t h u s , and Amphi od j a - C a r d i t a , show good a g r e e m e n t w i t h t h e ra n k o r d e r f o r t h e o v e r a l l sam ple s e t , w i t h v a l u e s o f 0 .7 0 7 , 0 . 6 5 2 , 0 .5 9 2 , and 0 .4 5 2 r e s p e c t i v e l y . The p o l y c h a e t e a s s o c i a t i o n s , N o t h r i a - T e l l i n a , ( S i e g e l , 1956, p . 212) The r e a s o n f o r t h e low v a l u e o f W ( 0 . 3 5 9 ) i s im m ed i- A l l o t h e r v a l u e s a r e above 0 . 4 0 0 . The " o p h i u r o i d - 131 T a b le 8 . C o m p ariso n o f S ed im en t V a r i a b l e s o f N o t h r i a - - S p io p h a n e s A s s o c i a t i o n and th e M a in la n d S h e l f . The v a l u e s a r e m eans. Sand C o n t e n t , P e r c e n t S i l t C o n t e n t , P er c e n t C la y C o n t e n t , P e r c e n t M edian D ia m e te r , m i l l i m e t e r s S o r t i n g C o e f f i c i e n t E n t i r e S h e l f (176 s a m p le s ) 44.4% 48.4% 7.2% 0 .0 8 2 mm 1 .7 1 O r g a n ic N i t r o g e n C o n t e n t , P e r c e n t 0.046% N o t h r i a - - S ^ ro p h a n e s (.7 s a m p le s ) 96.7% 27 .7% (1.9% )* 0 . 321mm 1 .3 3 0.017% *A s i n g l e o b s e r v a t i o n 132 T a b le 9. C om parison o f S ed im en t V a r i a b l e s o f th e L i s t r i o lo b u s A s s o c i a t i o n and th e M a in la n d S h e l f . The v a l u e s a r e m eans. E n t i r e S h e l f L i s t r i o l o b u s (1 7 6 sa m p le s) (9 samples') Sand C o n t e n t , P er c e n t 44.4% 13.1% S i l t C o n t e n t , P er c e n t 48.4% 72.6% C lay C o n t e n t , P e r c e n t 7.2% 24.6% M edian D ia m e te r , m i l l i m e t e r s 0 .0 8 2 mm 0 .0 2 7 mm S o r t i n g C o e f f i c i e n t 1 .7 1 2 .4 6 O rg a n ic N i t r o g e n C o n te n t, P er c e n t 0.046% 0.064% 133 C h l o e i a - P e c t i n a r i a , and D i o p a t r a , show m o d e ra te a g r e e m e n t, w i t h v a l u e s o f 0 .5 2 6 , 0 .4 7 5 , and 0 .4 0 7 r e s p e c t i v e l y . Summary D i s c u s s i o n O nly a few s p e c i e s out o f a l l t h o s e c o l l e c t e d w ere b o t h f r e q u e n t ( i n 40 p e r c e n t o r more o f t h e s a m p le s ) and r e a s o n a b l y num erous (1 5 s p e c im e n s p e r s q u a r e m e te r o r m o re ). By co m p a rin g t h r e e l i s t s o f th e 50 t o p - r a n k e d s p e c i e s o r d e r e d b y f r e q u e n c y o f o c c u r r e n c e , by p o p u l a t i o n d e n s i t y and by number o f a f f i n i t i e s ( F a g e r , 1 9 5 7 ), th e f a u n a l e l e m e n t s i n c l u d e d i n a l l t h r e e r a n k i n g s w ere d e t e r m i n e d . T h e re a r e 24 o f t h e s e p r e v a l e n t s p e c i e s ( T a b le 4 ; e x c l u d i n g e l e m e n t s i d e n t i f i e d o n ly t o h i g h e r t a x o n s ) . T h e se 24 c o m p ris e o n ly 1 .6 p e r c e n t o f t h e b e n t h i c m a c r o f a u n a l i n v e r t e b r a t e s o f t h e m a in la n d s h e l f . N e v e r t h e l e s s , b e c a u s e o f t h e i r n e a r l y u b i q u i t o u s d i s t r i b u t i o n , t h e i r r e l a t i v e ab u n d an ce and t h e i r t e n d e n c y t o c o - o c c u r f r e q u e n t l y w i t h a number o f o t h e r s p e c i e s , t h i s g r o u p o f s p e c i e s m u st be c o n s i d e r e d a m a jo r f a u n a l com ponent o f th e m a in la n d s h e l f . They i n c l u d e th e o p h i u r o i d A m phiodia u r t i c a , d e s i g n a t e d a s th e " d o m in a n t" o r g a n is m o f t h e m ost w i d e l y d i s t r i b u t e d c l a s s i c a l l y d e f i n e d a s s o c i a t i o n on th e s h e l f . A m ph io d ia u r t i c a i s a l s o c o n s i d e r e d " c o - d o m in a n t" o r " s u b - d o m in a n t" i n s e v e r a l r e l a t e d a s s o c i a t i o n s ( B a r n a r d and Z i e s e n h e n n e , 1 9 6 1 ). E i g h t o t h e r s p e c i e s l i s t e d i n T a b le 4 h a v e b e e n r e c o g n i z e d a s i m p o r t a n t f a u n a l e le m e n ts o f t h e o p h i u r o i d a s s o c i a t i o n s : P e c t i n a r i a 134 c a l i f o r n i e n s i s , G ly c e r a c a p i t a t a , S t e r n a s p i s f o s s o r , A x in o p s id a s e r r i c a t a , P r i o n o s p i o m a lm g r e n i, P r i o n o s p i o p i n n a t a , A m p h ip h o lis s q u a m a ta and G l o t t i d i a a l b i d a ( B a r n a r d and Z ie s e n h e n n e , 1961; T a b le s 3 , 4 , 5, 6 , 7 , 8 and 9 ) . Among t h e s p e c i e s l i s t e d i n T a b le 4 a r e f o u r o t h e r s t h a t w ere d e s i g n a t e d a s a s s o c i a t i o n " d o m in a n ts ” i n t h e p r i o r a n a l y s i s o f t h e s h e l f f a u n a : P e c t i n a r i a c a l i f o r n i e n s i s ( " c o - d o m i n a n t " w i t h C h l o e i a p i n n a t a o f an o u t e r - s h e l f and s lo p e a s s o c i a t i o n ) , P r i o n o s p i o m alm g ren i ( " d o m in a n t" o f a s h a llo w - z o n e sa n d a s s o c i a t i o n ) and T h a ry x t e s s e l a t a and S p io p h a n e s m i s s i o n e n s i s (m in o r a s s o c i a t i o n " d o m i n a n t s " ) . The 24 s p e c i e s d e s c r i b e d above a s p r e v a l e n t o c c u r r e d above a d e s i g n a t e d minimum l e v e l ( f r e q u e n c y , 40 p e r c e n t o f sa m p le s ; d e n s i t y , 15 s p e c im e n s p e r s q u a r e m e te r ) i n n e a r l y a l l s u b f i l e s o f a l l v a r i a b l e s m e a s u re d . When t h e y w ere a b s e n t fro m a s u b f i l e i t was u s u a l l y one a t e i t h e r e x tr e m e o f t h e r a n g e o f t h e p a r t i c u l a r v a r i a b l e (S e e T a b le 5 )1 On th e o t h e r h a n d , a number o f s p e c i e s d i s t r i b u t i o n s w ere c l e a r l y r e l a t e d t o v a r i a t i o n w i t h i n one or m ore e n v i r o n m e n ta l v a r i a b l e s . K e n d a l l C o e f f i c i e n t o f C o n c o rd a n c e (W) v a l u e s f o r r a n k i n g s w i t h i n s u b f i l e s o f fo u r v a r i a b l e s ( a r e a , d e p t h , san d c o n t e n t , and o r g a n i c n i t r o g e n c o n t e n t ) ra n g e d fro m 0 .5 3 2 t o 0 .6 3 5 (Xs = 251 t o 4 2 4 , p < 0 .0 1 ) . T hese c o r r e l a t i o n s i n d i c a t e good a g re e m e n t b e tw e e n th e s e t s o f r a n k i n g s f o r e a c h v a r i a b l e and s u g g e s t t h a t t h e d i v e r g en ce c r e a t e d by s p e c i e s l i m i t e d t o a p a r t i c u l a r p o r t i o n o f 135 t h e ra n g e (o n e o r a few s u b f i l e s ) i s o f f s e t by t h o s e t h a t e x te n d t h r o u g h o u t t h e r a n g e . The 24 p r e v a l e n t s p e c i e s o c c u r r e d i n a t l e a s t tw o - t h i r d s o f t h e c l a s s i c a l l y d e f i n e d a s s o c i a t i o n s o f th e s h e l f . When t h e 100 m ost f r e q u e n t s p e c i e s i n t h e 1 7 6 -sa m p le s e t w ere r e o r d e r e d w i t h i n n i n e a s s o c i a t i o n s u b f i l e s , 33 s p e c i e s a p p e a re d i n 40 p e r c e n t o r more o f t h e sa m p le s i n a t l e a s t s i x o f th e n in e s u b f i l e s . I n c l u d e d w e re 19 o f t h e 24 s p e c i e s o f T a b le 4 . The K e n d a l l C o e f f i c i e n t of C o n c o rd a n c e a n a l y s i s , a p p l i e d t o d e n s i t y r a n k i n g s by a s s o c i a t i o n , y i e l d e d a W o f 0 .3 5 9 . The c o n c o rd a n c e b e tw e e n t h e s e n i n e r a n k i n g s i s c o n s i d e r a b l y lo w e r t h a n t h a t f o r any o f th e f o u r p h y s i c a l v a r i a b l e s t e s t e d by W, b u t i t i s g r e a t e r th a n t h a t w h ich w ould be e x p e c t e d by ch a n c e ( p < 0 . 0 1 ) . T h is r e l a t i v e l y low c o r r e l a t i o n r e f l e c t s d i f f e r e n c e s among a s s o c i a t i o n s i n th e e x t e n t t o w h ich t h e i r r a n k d i s t r i b u t i o n o f s p e c i e s i s s i m i l a r t o t h a t f o r th e e n t i r e s h e l f a s s a m p le d . C a l c u l a t i o n o f S p e a rm a n ’ s rh o f o r e a c h com m unity s u b f i l e r a n k i n g com pared w i t h t h e s e l e c t e d s t a n d a r d r a n k i n g l i s t y i e l d e d r s v a l u e s r a n g i n g from 0 .7 0 7 t o 0 . 1 5 5 . The " o p h i u r o i d - d o m i n a t e d " a s s o c i a t i o n s show g e n e r a l a g re e m e n t ( 0 .7 0 7 t o 0 .4 5 2 ) w i t h th e r a n k o r d e r f o r t h e o v e r a l l sam ple s e t . The p o l y c h a e t e a s s o c i a t i o n s show m o d e ra te a g re e m e n t ( 0 .5 2 6 t o 0 . 4 0 7 ) . Two a s s o c i a t i o n s , t h e N o t h r i a - S p io p h a n e s ( 0 .2 2 6 ) and L i s t r i o l o b u s ( 0 . 1 5 5 ) , show p o o r a g r e e m e n t. Each o f t h e s e two d i s t i n c t i v e 136 f a u n a l a s s o c i a t i o n s i n h a b i t s s e d im e n ts t h a t d e v i a t e m a rk e d ly fro m th e g e n e r a l s e d im e n t a r y e n v ir o n m e n t o f th e s h e l f ( T a b l e s 8 and 9 ) . S p e c i e s D i s t r i b u t i o n a l P a t t e r n s and M a c ro f a u n a l A s s o c i a t i o n s I n t h e p r e c e d i n g s e c t i o n th e e m p h a s is i s p l a c e d u p o n th e i d e n t i f i c a t i o n o f th e p r e v a l e n t s p e c i e s o f th e b e n t h i c i n v e r t e b r a t e m a c ro fa u n a o f t h e s h e l f . T h i s f a u n a l f r a c t i o n i s p r o m in e n t (o n t h e b a s i s o f t h e r a n k o r d e r o f i t s m em bers) o v e r th e r a n g e o f t h e s e l e c t e d e n v ir o n m e n ta l v a r i a b l e s i n v e s t i g a t e d . T h e se s p e c i e s a r e a l s o t i m p o r t a n t e l e m e n t s i n m ost ( 2 / 3 ) o f th e p r e v i o u s l y d e f i n e d a s s o c i a t i o n s o f th e s h e l f . T h is s e c t i o n e x p a n d s t h e e v a l u a t i o n o f s p e c i e s d i s t r i b u t i o n a l p a t t e r n s r e l a t i v e t o th e b e n t h i c m a c r o f a u n a l a s s o c i a t i o n s i n w h ic h t h e y a r e c o n s i d e r e d m em bers. The a n a l y s i s i s l i m i t e d t o th e c o n s i d e r a t i o n o f t h e t h r e e m a jo r b e n t h i c a s s o c i a t i o n s o f th e S a n t a B a r b a r a s h e l f (A re a I I ) : th e N o t h r i a - T e l l i n a a s s o c i a t i o n , t h e L i s t r i o l o b u s a s s o c i a t i o n and th e A m p h io d ia - C a r d i t a a s s o c i a t i o n . T hese t h r e e a s s o c i a t i o n s a r e p a r t i a l l y s e g r e g a t e d by d e p t h ; t h e N o t h r i a - T e l l i n a a s s o c i a t i o n i s r e s t r i c t e d to t h e s h a l l o w p o r t i o n o f t h e s h e l f ( c a . 1 0 -3 5 m e t e r s ) ; th e L i s t r i o l o b u s a s s o c i a t i o n , to t h e i n t e r m e d i a t e p o r t i o n o f t h e s h e l f ( c a . 25 -7 0 m e t e r s ) ; and t h e A m p h io d ia - C a r d i t a a s s o c i a t i o n , to t h e o u t e r 137 ( d e e p e r ) p o r t i o n o f t h e s h e l f ( c a . 5 0 -1 0 5 m e t e r s ) . The 38 s p e c i e s s e l e c t e d f o r c o n s i d e r a t i o n i n t h i s a n a l y s i s have a l l b een i d e n t i f i e d a s i m p o r t a n t e l e m e n t s o f one o r more o f t h e s e t h r e e a s s o c i a t i o n s ( B a r n a r d and H a r t man, 1959, T a b l e s 1, 2 and 3 f o r L i s t r i o l o b u s , T a b le 4 f o r A m p h io d ia - C a r d i t a , and T a b le 5 f o r N o t h r i a - T e l l i n a ; B a r n a r d and Z i e s e n h e n n e , 1961, T a b le 4 f o r A m p h io d ia - C a r d i t a , and B a r n a r d , 1963, T a b le s 4 , 5 and 6 f o r N o t h r i a - T e l l i n a ) . The d e p t h d i s t r i b u t i o n o f e a c h o f t h e s e s p e c i e s i s i l l u s t r a t e d i n F i g u r e s 1 0 a, b , c and d . T h e se p l o t s a r e b a s e d on d a t a fro m 56 s t a t i o n s ( t h e 41 s a m p le s of t h e 176 s a m p le s o f t h e s t r a t i f i e d s e t s u p p l e m en ted by 14 a d d i t i o n a l c o m p l e t e l y s o r t e d s a m p l e s ) . The s a m p le s w ere g ro u p e d by d e p t h o f c o l l e c t i o n i n t o i n c r e m e n t s o f 5 m e t e r s b e g i n n i n g w i t h a d e p t h o f 10 m e t e r s ; d a t a fro m s a m p le s c o l l e c t e d a t d e p t h s o v e r 105 m e t e r s w ere n o t u s e d a s t h i s d e p t h i s s l i g h t l y b e lo w th e o u t e r l i m i t o f th e d e e p e s t a s s o c i a t i o n (A m p h io d ia - C a r d i t a ) s t u d i e d . The mean d e n s i t y (mean n u m b e r /0 .2 5 s q u a r e m e t e r s ) o f e ach s p e c i e s c o n s id e r e d was c a l c u l a t e d f o r e a c h g ro u p o f s a m p le s i n c l u d e d w i t h i n e a c h 5 m e te r d e p th i n c r e m e n t . The p l o t s a r e p la c e d so t h a t t h e s u c c e s s i v e s p e c i e s show a g e n e r a l p r o g r e s s i o n fro m s h a l l o w e r t o d e e p e r w a t e r i n o r d e r to com pare t h e i r d i s t r i b u t i o n s w i t h th e d e p t h d i s t r i b u t i o n s o f t h e t h r e e a s s o c i a t i o n s . For c o m p a r a tiv e p u rp o ses, a t th e b o tto m o f e a c h f i g u r e t h r e e h o r i z o n t a l b a r s i n d i c a t e Figures lOa-lOd P o p u l a t i o n D e n s i t y P l o t s f o r 38 S e l e c t e d S p e c i e s from th e N o t h r i a - T e l l i n a , L i s t r i o l o b u s and A m p h io d ia - C a r d i t a A s s o c i a t i o n s o f th e S a n t a B a r b a r a S h e l f A rra n g e d by D e p th . H o r i z o n t a l b a r s i n d i c a t e th e d e p th d i s t r i b u t i o n o f t h e sa m p le s d e s i g n a t e d a s r e p r e s e n t a t i v e o f th e t h r e e a s s o c i a t i o n s (A p p e n d ix T a b le A - 3 ) . P o p u l a t i o n d e n s i t y i s e x p r e s s e d as t h e mean number o f s p e c im e n s p e r q u a r t e r s q u a re m e te r b a s e d on th e s a m p le s o f e a c h f i v e m e te r d e p t h i n c r e m e n t . 138 139 tr Ld H IT < Z> o i n CM < tr U J c n < iij S SPIOPHANES BOMBYX _ O LIVELL A BAETICA 100 — 9 0 — 8 0 — MAGELONA SACCULATA 7 0 — HAPL0SC0L0PL0S ELONGATUS 6 0 — 0 5 0 4 0 — 3 0 PRIONOSPIO MALMGRENI 20 CHAETOZONE CORONA 1 0 — o l MACOMA YOLDIFORMIS NOTHRIA ELEGANS TELL1NA BUTTONI SOLEN SP. P IS T A ^ S J U N C T A AXIOTHELL A RUBROCINCTA NOTHRIA-TELLINA •LISTRIOLOBUS -AM PHIO DIA-CARDITA I I I I I I I I I I I I I I I I I I I I I 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0 8 5 9 0 9 5 1 0 0 1 0 5 1 1 0 DEPTH IN M ETER S Figure 10a 140 = — .G LY C E R A AMERICANA e f t C E L lJ h- UJ Z u i C C 4 Z> o « 0 lO C M m 2 D Z 4 li i 2 loo se - 00 — 7 0 — I SPIOPHANES MISSIONENSIS , LISTRIOLOBUS PELODES STERNASPIS FOSSOR 0 MARPHYSA DISJUNCTA 0 ■ — — PHORONIDS , c o m p s o m y a x s u b d ia p h a n a 6 0 - 5 0 — AMPHIPHOLIS SQUAMATA 4 0 — 0 1 3 0 — 20 — C ALLIA N ASA CALIFO RNIENSIS 10 — LISTR IELLA GOLETA 0 — 1TEREBELLIDES STROEM I l SAXICAVELLA PACIFICA 0 iCERATO CEPHALA C. AMERICANA ■NOTHRIA-TELLINA ■LISTRIOLOBUS ■AMPH10DIA- CARDITA I I I I I I I I I I I I I I I I I I I I I 10 1 5 2 0 25 3 0 35 4 0 45 5 0 5 5 6 0 65 7 0 7 5 8 0 8 5 9 0 9 5 100 105 1 1 0 DEPTH IN M E TE R S Figure 10b 141 I p r io n o s p io p in n a t a 0 P EC TIN A RIA CALIFORNIENSIS < /) O r UJ l- L U 2 U l CL < 3 O UJ o r UJ m X < UJ 2 100 ■ 9 0 ■ 8 0 ■ 7 0 • 6 0 ■ 5 0 4 0 3 0 20 1 0 0 CARDITA VENTRIOO SA 0 NUCULA SPP. AXINOPSIDA SERRICATA P S E P H ID IA LORDI B ITTIUM R. SUBPLANATUM 0 N O TH R IA -TE LU N A ■LISTRIOLOBUS -A M P H IO D IA - CARDITA I I I I I I I I I I I I I I I I I I I I I 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0 8 5 9 0 9 5 1 0 0 1 0 5 1 1 0 DEPTH IN M ETER S Figure 10c 142 in 100 — tr £ 9 0 — u j < r < 3 a CV j a . UJ c a -2 « s UJ 5 8 0 — ?0 — 6 0 — 5 0 — 4 0 3 0 — 20 — 1 0 — AMPHIODIA URTICA AMPELISCA PACIFICA MALDANE SARSI CHLOEIA PINNATA ADONTORHINA CYCLIA 'N O T H R IA -T E L L IN A -LISTRIOLOBUS “AMPHIODIA- CARDITA I I I I I I I I I I I I i I I I I I I I 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0 8 5 9 0 9 5 1 0 0 1 0 5 1 1 0 DEPTH IN METERS F i g u r e lOd 143 th e d e p t h d i s t r i b u t i o n o f th e s a m p le s d e s i g n a t e d b y B a rn a rd (A p p e n d ix T a b le A-3) a s r e p r e s e n t a t i v e o f t h e t h r e e a s s o c i a t i o n s . The p l o t s fo rm a c o n t i n u o u s s e r i e s o f o v e r l a p p i n g d i s t r i b u t i o n a l p a t t e r n s a lo n g t h e d e p t h c o n tin u u m . The ma j o r i t y o f th e p l o t s h av e com plex c o n f i g u r a t i o n s m aking g e n e r a l i z e d d e s c r i p t i o n d i f f i c u l t . I n s p e c t i o n o f F i g u r e s 1 0 a, b , c , and d r e v e a l s t h a t s u b s t a n t i a l d i f f e r e n c e s among t h e s p e c i e s e x i s t a s to t h e e x t e n t o f t h e i r d e p t h r a n g e s , t h e i r r e l a t i v e ab u n d an ce and th e sh a p e o f t h e i r d e n s i t y p r o f i l e s w i t h d e p t h . Many o f t h e p l o t s have com plex s h a p e s w i t h m u l t i p l e h i g h d e n s i t y p e a k s . The P e c t i n a r i a c a l i f o r n i e n s i s p l o t i s an ex am p le o f t h i s d i s t r i b u t i o n a l p a t t e r n . Some o f th e c u r v e s a r e b im o d a l ( N o t h r i a e l e g a n s , F ig u r e 1 0 a ) . Normal c u r v e s a r e n o t t y p i c a l ( c l o s e s t a p p r o x i m a t i o n i s C a l l i a n a s a c a l i f o r n i e n s i s , F i g u r e 1 0 b ) . F o u r te e n o f t h e 38 s p e c i e s s p a n th e e n t i r e d e p th co n tin u u m ; o t h e r s a lm o s t r e a c h t h i s w id e r a n g e , i n c l u d i n g n i n e p r e v a l e n t s p e c i e s (T a b le 4 ) . S p e c i e s w i t h p e a k s o f ab u n d an ce a t t h e e x tr e m e s o f th e r a n g e , p a r t i c u l a r l y t h o s e i n d e e p w a t e r , o f t e n show skewed d i s t r i b u t i o n a l c u r v e s w i t h lo n g " t a i l s ” o f low d e n s i t y . S p e c ie s w i t h r e l a t i v e l y r e s t r i c t e d r a n g e s a r e more p r e v a l e n t i n s h a ll o w w a te r th a n i n d e e p e r w a t e r . T h e re a r e a lm o s t no s p e c i e s w i t h l i m i t e d d e p th r a n g e s a t i n t e r m e d i a t e d e p t h s . P o i n t s o f h i g h d e n s i t y a r e a b o u t e q u a l l y d i s t r i b u t e d w i t h i n t h e d e p t h r a n g e o f e a c h 144 a s s o c i a t i o n . T h e re i s a te n d e n c y f o r some s h a l l o w - w a t e r s p e c i e s to be r e s t r i c t e d to a d e p t h ra n g e n o t much g r e a t e r t h a n t h a t o f th e N o t h r i a - T e l l i n a a s s o c i a t i o n . Any g ro u p o f s p e c i e s s u c h a s t h i s i s , o f c o u r s e , d i s t r i b u t e d a lo n g as many c o n t i n u a as t h e r e a r e v a r i a b l e s t o w hich th e s p e c i e s r e a c t . C o n s e q u e n tly i t i s p o s s i b l e to d e f i n e in n u m e ra b le c o n t i n u a w i t h i n any com plex e n v ir o n m e n t. W hile n - d i m e n s i o n a l r e l a t i o n s h i p s a r e i m a g i n a b l e , th e y a r e i m p o s s i b l e to r e p r e s e n t i n a s im p le g r a p h i c fo rm . The n e x t s t e p fro m t h e s i n g l e v a r i a b l e i s a s c a t t e r g r a p h d e f i n e d by two v a r i a b l e s . I n t r o d u c t i o n o f a se co n d v a r i a b l e i n c r e a s e s th e f a c i l i t y w i t h w h ic h s p e c i e s d i s t r i b u t i o n a l p a t t e r n s can be r e l a t e d to th e c o n f i g u r a t i o n s o f t h e s e t h r e e a s s o c i a t i o n s . A s e d im e n t v a r i a b l e , m e d ia n d i a m e t e r i n m ic r o n s , and d e p t h ( i n m e t e r s ) h av e been com bined to c o n s t r u c t a g r a p h . The 55 s a m p le s ( s e d i m e n t d a t a i s l a c k i n g f o r one sa m p lin g l o c a t i o n ) o f A re a I I w ere p l o t t e d on t h i s g ra p h by e a c h o f t h e s e v a r i a b l e s ; th e s c a l e o f th e a b s c i s s a (m e d ia n d i a m e t e r ) i n t h e p r e s e n t f i g u r e s i s p l a c e d so t h a t th e c o a r s e d i a m e t e r s a r e a t th e same c o r n e r a s th e s h a ll o w d e p t h s , a s t h i s c o m b in a tio n a p p r o a c h e s th e s i t u a t i o n e x i s t in g on th e s h e l f . The d i s t r i b u t i o n s o f 44 s p e c i e s ( i n c l u d i n g th e 38 shown i n F i g u r e s 1 0 a, b , c and d ) a r e p l o t t e d on su ch g ra p h s i n F i g u r e s 11 t o 54. The c u rv e d c o n t o u r s o f e ach Figures 11-54 A S e r i e s o f 44 S p e c i e s D e n s i t y D i s t r i b u t i o n s P l o t t e d a t 55 S am p lin g L o c a t i o n s o f th e S a n ta B a r b a r a A re a A r ra n g e d on a G raph D e fin e d by a S e d im e n t V a r i a b l e , M edian D ia m e te r i n M ic r o n s , and b y D epth i n M e t e r s . The c u rv e d c o n t o u r s i n d i c a t e p o p u l a t i o n d e n s i t i e s o f 1 or m o re, 10 or m ore and 75 or more ( a s i n g l e f i g u r e , A m ph io d ia u r t i c a , p . 163) s p e c i mens p e r q u a r t e r s q u a r e m e te r . The num bers w i t h i n th e a r e a s e n c l o s e d by t h e s e c o n t o u r s a r e th e minimum v a l u e s . S t a t i o n s o f th e N o t h r i a - T e l l i n a , L i s t r i o l o b u s and A m p h io d ia - C a r d i t a a s s o c i a t i o n s a r e e n c l o s e d i n p o l y g o n a l s h a p e s by s t r a i g h t l i n e s . A s i n g l e f i g u r e i e g e n d i s u se d f o r t h i s s e r i e s so t h a t t h e s e f i g u r e s may more e a s i l y be v ie w e d i n s e q u e n c e . 145 SPIOPHANES BOMBYX NOTHRIA TELLINA AMPHIODIA.- CARDITA MEDIAN DIAMETER IN MICRONS -P=> o Figure 11 DEPTH I N METERS GONIADA LITTOREA 5- 0- 15- 20- NOTHRIA 2 5 - TELLINA 3 0 - 35- 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - A M PH IO D IA - CARDITA 8 0 - 8 5 - 9 0 - 95- 100 - 1 0 5 - 110 5 0 120 100 90 8 0 7 0 6 0 40 30 130 110 20 MEDIAN DIAMETER IN MICRONS Figure 12 0 5 - 10- 15- 2 0 - 2 5 - 3 0 - 35- 4 0 - 4 5 - 5 0 - 5 5 ~ 6 0 - 6 5 7 0 — | 7 5 8 0 - 8 5 - 9 0 9 5 - 100- 1 0 5 110 to < r U J i- U J z I I- C L U J Q MAGELONA SACCULATA NOTHRIA TELLIN'A. A M P H IO D IA - CARDITA I • J T " T " 10 13 0 120 1 1 0 T T 1 0 0 9 0 8 0 7 0 6 0 5 0 MEDIAN DIAM ETER IN MICRONS 4 0 I 3 0 20 Figure 13 CHAETOZONE CORONA 5 - 10- 5 — 20- NOTI 25- TELLINA 3 0 - 35- 4 0 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - AMPHIODIA - CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 110 100 9 0 8 0 7 0 MEDIAN DIAMETER IN MICRONS 3 0 20 130 6 0 5 0 4 0 120 Figure 14 in ce UJ i- tu 5 X i— X ui o 0L1VELLA BAETICA 5 - 10- 15- 2 0 - 2 5 - TELLINA 3 0 - 3 5 - 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - AMPHIODIA - CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 105 110 130 100 9 0 8 0 7 0 6 0 5 0 MEDIAN DIAMETER IN MICRONS 120 4 0 20 3 0 H L n O Figure 15 DEPTH I N METERS TELLINA BUTTONI NOTHRIA TELLINA AMPHIODIA - CARDITA MEDIAN DIAMETER IN MICRONS Figure 16 NOTHRIA TELLINA AM PHIODIA- CARDITA 130 120 110 100 9 0 8 0 7 0 6 0 5 0 4 0 3 0 2 0 10 MEDIAN DIAMETER IN MICRONS Figure 17 AXIOTHELLA RUBROCINGTA NOTHRIA TELLINA AM PHIO DIA- CARDITA 130 120 110 100 9 0 8 0 7 0 6 0 5 0 4 0 3 0 2 0 10 MEDIAN DIAMETER IN MICRONS U l U > Figure 18 PRIONOSPIO MALMGRENI NOTHRIA T E L L IN A A M P H IO D IA - CARDITA MEDIAN DIAM ETER IN MICRONS SPIOPHANES MISSIONENSIS NOTHRIA TELLINA AM PHIODIA- CARDITA 130 120 110 100 9 0 8 0 7 0 6 0 5 0 4 0 3 0 2 0 10 MEDIAN DIAMETER IN MICRONS U l U \ Figure 20 PRIONOSPIO PINNATA NOTHRIA TELLIN AMPHIODIA _ CARDITA 130 120 110 100 9 0 8 0 7 0 6 0 -5 0 4 0 3 0 2 0 10 MEDIAN DIAMETER IN MICRONS Figure 21 DEPTH I N METERS AMPHIPHOLIS SQUAMATA 5 - 10- 1 5 - 20- 2 5 - -T.ELLINA 3 0 - 35- 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 75- A M PH IO D IA - CARDITA 6 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 110 100 9 0 8 0 7 0 6 0 MEDIAN DIAMETER IN MICRONS 5 0 4 0 3 0 20 130 120 .Figure 22 DEPTH I N METERS GONIADA BRUNNEA 5 - 10- 7 15- 20 — NOTHRIA - 2 5 - TELLINA . 3 0 - 35- 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - M PHIO DIA- CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100 - 1 0 5 - 110 4 0 3 0 7 0 6 0 5 0 20 100 9 0 8 0 MEDIAN DIAMETER IN MICRONS 130 120 F ig u re 23 m < r H I 2 T h- Q . U ] Q HAPLOSCOLOPLOS ELONGATUS 5 - 10- 15- 2 0 - N0TH R 1A - 2 5 - TELLIN A 3 0 - 3 5 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - A M P H IO D IA - CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 110 3 0 20 5 0 4 0 8 0 7 0 6 0 1 0 0 9 0 MEDIAN DIAM ETER IN MICRONS 120 1 1 0 1 3 0 i-1 U 'l o F ig u re 24 k 0 5 -i 1 0 15- 20 - 25- 3 0 - 35 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - 8 0 - 85- 9 0 - 9 5 - 100 105 no (/) IT UJ s z I H * CL UJ o © R 0C H EF0RTIA ALEUTICA 7 O TH R IA - TEL LIN A AM PHIO DIA- CARDITA Q G ) r •y ✓ / — r ~ 70 — I -------- 1 6 0 50 — r ~ 30 T" 1 0 130 T T 120 1 1 0 i 80 100 9 0 MEDIAN DIAMETER IN MICRONS 40 20 O F ig u re 25 SOLEN SP. 5 - 10- r ~ ~ 1 5 - 20- 2 5 - NOTHRIA- TELLINA 3 0 - 35- 4 0 - V) sr UJ t- L U s 4 5 - 5 0 - 5 5 - z 6 0 - x 6 5 - 7 0 - H Q . UJ O 7 5 - A M PHIO DIA- CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 1 10 4 0 100 9 0 8 0 7 0 MEDIAN DIAMETER IN MICRONS 50 30 20 60 130 120 O' I-1 F igure 26 DEPTH I N METERS MACOMA YOLDIFORMIS 15- 2 0 - OTHRIA - TELLINA 3 0 - 35- 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - AM PHIODIA- CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 1 1 0 100 9 0 8 0 70 MEDIAN DIAMETER IN MICRONS 130 50 4 0 30 120 6 0 20 F ig u re 27 I 0 5 - 10- 15- 20 - 2 5 - 3 0 - 3 5 - 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 65- 7 0 - 7 5 - 8 0 - 8 5 9 0 - 9 5 - 100 - 1 0 5 - 11 0 w > a . U J i- U J S I i- D . U J Q © PISTA DISJUNCTA A M PH IO D IA - CARDITA G NOTHRIA- TELLINA * ) ■ / / —i ------------ 1 ------------ 1 -------------1 ------------1 ------------ 1 ------------ 1 ------------ 1 ------------ 1 ------------ 1 ------------ 1 ------------ 1 ------------ r - 130 120 110 100 9 0 8 0 7 0 6 0 5 0 4 0 3 0 2 0 10 MEDIAN DIAMETER IN MICRONS F ig u re 28 GLYCERA AMERICANA 5 - 10- 15- 20 - NOTHRIA- 2 5 - TELLINA 3 0 - 3 5 - 4 0 - 4 5 - U J 5 0 - iii S 5 5 - 6 0 - 6 5 - u i 7 0 - 7 5 - A M PHIO DIA- CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 110 4 0 3 0 20 100 9 0 8 0 7 0 6 0 MEDIAN DIAMETER IN MICRONS 50 130 120 o • £ > F igure 2 9 MAGELONA PACIFICA N2IURIA. TELLINA AM PHIO DIA- CARDITA 130 120 110 100 9 0 8 0 7 0 6 0 50 4 0 30 20 MEDIAN DIAMETER IN MICRONS O' L n F igure 30 0 5 - 10- 15- 2 0 - 2 5 - 3 0 - 3 5 - 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - MO (/) a: UJ H UJ I H Q . UJ O CERIANTHIDS r ~ - NOTHRIA- TELLiNA AM PHIO DIA- CARDITA — I -------- 1 -------- 1 -------- 1 -------- 1 -------- 1 -------- 1 -------- 1 -------- 1 -------- 1 -------- 1 -------- 1 -------- T " 130 120 110 100 9 0 8 0 7 0 6 0 5 0 4 0 3 0 20 10 MEDIAN DIAMETER IN MICRONS I — 1 O' O ' F ig u re 31 DEPTH I N METERS MARPHYSA DISJUNCTA 5 - 10- 15- 20- NOTHRIA- 25- TELLINA 3 0 - 3 5 - 4 0 - 4 5 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - AM PH IO D IA - CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100 - 1 0 5 - 110 30 100 9 0 8 0 7 0 6 0 MEDIAN DIAMETER IN MICRONS 5 0 4 0 20 120 130 F igure 32 0 5 - 10- 15 20-1 25 3 0 - 3 5 - 4 0 - 4 5 - 50 55 6 0 6 5 - 7 0 - 75 8 0 - 8 5 - 9 0 9 5 - 100 - 1 0 5 - 1 1 0 < /) tr llJ f — L U S X t- CL UJ o CALLIANASA CALIFORNIENSIS ; © - \ \ NOTHRIA- TELLINA AM PHIODIA- CARDITA / • / / / ~ r~ 60 !30 120 n o 100 I 90 80 70 i 50 i 40 30 20 1 0 MEDIAN DIAMETER IN MICRONS o 00 F ig u re 33 LISTRIOLOBUS PELOOES 5 - 10- • J l . * f t 20- NOTHRIA- 2 5 - TELLINA 3 0 - 3 5 - 4 0 - < / ) < r 4 5 - 5 0 - ui 5 5 5 - z 6 0 - x H C L UJ O 7 5 - AM PHIO OIA- CARDITA 8 0 - 8 5 - 9 0 - 100 - 1 0 5 - 11 0 30 130 120 100 9 0 8 0 MEDIAN DIAMETER IN MICRONS 50 40 20 1 1 0 70 6 0 I - 1 o vO F ig u re 34 DEPTH I N METERS 5 - SAXICAVELLA PACIFICA 10- ©- 15- 20 - NOTHRIA- 2 5 - TELLINA 3 0 - 3 5 - 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - AMPHIODIA - CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 110 130 100 9 0 8 0 7 0 6 0 50 MEDIAN DIAMETER IN MICRONS 4 0 120 1 1 0 30 20 F ig u re 35 DEPTH I N METERS PHORONIDS NOTHRI, ELLINA A M PHIO DIA- CARDITA 130 120 110 100 9 0 8 0 7 0 6 0 5 0 4 0 3 0 2 0 10 MEDIAN DIAMETER IN MICRONS F ig u re 36 0 5 10- 15- 2 0 - 2 5 - 3 0 - 3 5 - 4 0 4 5 - 5 0 - 55 6 0 - 6 5 - 7 0 - 75- 8 0 - 8 5 - 9 0 - 9 5 - 100— 1 0 5 - M O to o c UJ h UJ S x H Q- UJ Q LISTRIELLA 6 0L E T A N O TH R IA - TELLINA f t 1 0 AM PHIO DIA- CARDITA / T — T~ 100 9 0 8 0 7 0 6 0 50 MEDIAN DIAMETER IN MICRONS T 130 120 “I — no T T 4 0 30 20 1 0 1 - * -4 b o F ig u re 37 COMPSOMYAX SUBDIAPHANA 5 - 10- 15- 20 - NOTHRIA 2 5 - TELLINA 35- 4 0 - w a . 4 5 - LU \— UJ 2 5 0 - 5 5 - z 6 0 - x h - CL UJ O 75- AM PHIO DIA- CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 110 130 120 1 1 0 100 9 0 8 0 7 0 MEDIAN DIAMETER IN MICRONS 6 0 50 4 0 30 20 U ) F ig u re 38 PSEPHIDIA LORDI 10- ---- 0 15- 20 - NOTHRIA- 2 5 - TELLINA 35- 4 0 - c o 4 5 - L l ) 5 0 - U J 5 5 - z 6 0 - i 65- t- Q. LU O 7 0 - 7 5 - AM PH IO D IA - CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 1 0 5 - 1 1 0 30 20 5 0 4 0 100 9 0 8 0 7 0 MEDIAN DIAMETER IN MICRONS 60 130 120 F ig u re 39 MALDANE SARSI 5 - 10- 15- 20 - NOTHRIA - 2 5 - TELLINA 3 0 - 35- 4 0 - 4 5 - 5 0 - L l ) U J 5 5 - 6 0 - 6 5 - 7 0 - 7 5 - AMPHIODIA — CAROITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 110 100 90 80 7 0 60 50 40 30 20 1 0 130 120 1 1 0 MEDIAN DIAMETER IN MICRONS F ig u re 40 CERATOCEPHALA C. AMERICANA NOTHRIA TELLINA AMPHIODIA - CARDITA 130 120 1 1 0 100 90 80 70 60 50 40 30 20 10 MEDIAN DIAMETER IN MICRONS F ig u r e 4 1 CARDITA VENTRICOSA 5 - 10- 15- 20- NOTHRIA " 2 5 - TELLINA 3 0 - 35- 4 0 - v > IE UJ H UJ S 45~ 5 0 - 5 5 - z 6 0 - x i- Q . UJ o 6 5 - 7 0 - 75- AM PHIODIA- CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 105- 1 1 0 30 100 90 80 70 60 50 MEDIAN DIAMETER IN MICRONS 40 20 120 130 H 1 ~4 F ig u re 42 AMPELISCA PACIFICA NOTHRIA TELLINA AM PH IO D IA - CARDlTA' MEDIAN DIAMETER IN MICRONS F ig u r e 4 3 GLYCERA CAPITATA NOTHRtA TELLINA AM PHIODIA- CARDITA MEDIAN DIAMETER IN MICRONS F ig u r e 4 4 TEREBELLIDES STROEMI 5 - 10- 5 - 2 0 - NOTHRIA- TELLINA 3 0 - 35- 4 0 - c c Ll I 4 5 - 5 0 - i- LlJ 5 5 - 6 0 - x i- Q . U J O 6 5 - 7 0 - 7 5 - AMPHIODIA - CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 105- 110 100 90 80 70 MEDIAN DIAMETER IN MICRONS 130 120 50 40 30 20 no 60 l-1 00 o F ig u re 45 AMPHIODIA URTICA NOTHRIA TELLINA AM PHIO DIA- CARDITA MEDIAN DIAMETER IN MICRONS PECTINARIA CALIFORNIENSIS NOTHRIA TELLINA AM PHIO DIA- CARDITA MEDIAN DIAMETER IN MICRONS F ig u re 47 AXINOPSIDA SERRICATA NOTHRIA TELLINA M PH IO D IA - CARDITA 130 120 1 1 0 100 90 80 70 60 50 40 30 20 10 MEDIAN DIAMETER IN MICRONS F ig u re 4 8 to o r UJ l — UJ X C L L U O NUCULA SPP. 5 - 10- 20 - 2 5 - TELLINA 3 0 - 35- 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 65- 7 0 - 7 5 - AM PHIO DIA- CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 105- 11 0 30 20 70 60 50 40 130 120 1 1 0 100 90 MEDIAN DIAMETER IN MICRONS 80 I-4 o o ■ P * F ig u re 49 STERNASPIS FOSSOR 5 - 10- 15- 20 - NOTHRIA- 2 5 - TE LIIN A 3 0 - 3 5 - 4 0 - v > 4 5 - tii 5 0 - Ll I 5 5 - 6 0 - 6 5 - 7 0 - 75- AMPHIODIA - CARDUTA- 8 0 - 8 5 - 9 0 - 9 5 - 100 105- 1 1 0 30 20 40 60 100 90 MEDIAN DIAMETER IN MICRONS 80 70 50 120 130 F ig u re 50 CHLOEIA PINNATA NOTHRIA TELLINA A M PH IO D IA - CARDITA MEDIAN DIAMETER IN MICRONS BITTIUM R. SUBPLANATUM NOTHRIA TELLINA A M PHIODIA- CARDITA MEDIAN DIAMETER IN MICRONS 00 Figure 52 ADONTORHINA CYCLIA 5 - 10- 15- 2 0 - NOTHRIA- 25- • < TELLINA 3 0 - 35- 4 0 - (/} tr LJ h U J S 4 5 - 5 0 - 5 5 - z 6 0 - x t- 6 5 - 7 0 - Q . H I O 7 5 - AMPHIODIA - CARDITi 8 0 - 85- 9 0 - 9 5 - 100- 1 0 5 - 110 100 9 0 8 0 7 0 6 0 50 MEDIAN DIAMETER IN MICRONS 4 0 30 20 130 Figure 53 DEPTH I N METERS ONUPHIS NEBULOSA 5 - 0 - 15- 20 - NOTHRIA- 25- •6LLINA 3 0 - 3 5 - 4 0 - 4 5 - 5 0 - 5 5 - 6 0 - 6 5 - 7 0 - 75- AM PHIODIA- CARDITA 8 0 - 8 5 - 9 0 - 9 5 - 100- 1 0 5 - 110 30 20 8 0 70 6 0 50 40 130 120 1 1 0 100 9 0 MEDIAN DIAMETER IN MICRONS Figure 54 190 f i g u r e e n c l o s e p o i n t s w i t h v a l u e s o f one t o n in e sp e c im e n s p e r q u a r t e r s q u a r e m e te r ( o u t e r c o n t o u r ) and 10 or more s p e c im e n s p e r q u a r t e r s q u a r e m e te r ( i n n e r c o n t o u r ) ; i n one f i g u r e , A m ph io d ia u r t i c a , a t h i r d c o n to u r ( i n n e r m o s t ) has b e e n added t o i n d i c a t e 75 s p e c im e n s and o v e r per s q u a r e m e t e r . S t a t i o n s d e s i g n a t e d as i n d i c a t i v e o f th e N o t h r i a - T e l l i n a , L i s t r i o l o b u s , and A m p h io d ia - C a r d i t a a s s o c i a t i o n s a r e i n c l u d e d w i t h i n p o l y g o n a l s h a p e s fo rm ed o f s t r a i g h t l i n e s . The d i s t r i b u t i o n o f e v e r y s p e c i e s ca n t h e r e f o r e be com pared t o t h e d i s t r i b u t i o n o f t h e t h r e e a s s o c i a t i o n s . An a t t e m p t was made t o s t a r t t h e s e f i g u r e s w i t h s h a llo w w a te r s p e c i e s ( t h o s e c o i n c i d e n t w i t h th e N o t h r i a - T e l l i n a a s s o c i a t i o n ) and t o p r o c e e d t o s p e c i e s a p p r o x i m a ti n g th e d i s t r i b u t i o n o f t h e L i s t r i o l o b u s a s s o c i a t i o n , and f i n a l l y t o c o n c lu d e w ith t h o s e o f d e e p e r w a te r ( s p e c i e s p ro m in e n t i n th e A m p h io d ia - C a r d i t a a s s o c i a t i o n ) . P r e v a l e n t s p e c i e s o r o th e r w i d e - r a n g i n g fo rm s a r e p l a c e d i n t h e s e r i e s a t v a r i o u s p o i n t s ; t h e i r p o s i t i o n i n g was d e te r m in e d on th e b a s i s of t h e a s s o c i a t i o n s i n w h ich th e y a t t a i n e d t h e i r h i g h e s t popu l a t i o n d e n s i t i e s . The g r o u p in g o f a l l o f t h e s e s p e c i e s p a t t e r n s p r e s e n t e d h e r e i s i n p a r t s u b j e c t i v e and o t h e r a r r a n g e m e n ts c e r t a i n l y a r e p o s s i b l e . The r e s u l t o f t h i s a n a l y s i s i s a h i g h l y com plex s e r i e s o f p a t t e r n s . The d i s t r i b u t i o n s o f a number o f s p e c i e s conform c l o s e l y to th e a s s o c i a t i o n s w ith w h ich t h e y a r e a s s o c i a t e d . Such c o n f o r m i t y i s t r u e f o r S p jp p h a n e s bombyx, 191 G o n ia d a l i t t o r e a , C h a e to z o n e c o r o n a , M ageIona s a c c u l a t a , O l i v e l l a b a e t i c a , T e l l i n a b u t t o n ! , N o t h r i a e l e g a n s and S o le n s p . f o r th e N o t h r i a - T e l l i n a a s s o c i a t i o n ; L i s t r i o l o b u s p e l o d e s and S a x ic a v e 1 1 a p a c i f i c a f o r th e L i s t r i o l o b u s a s s o c i a t i o n ; and C a r d i t a v e n t r i c o s a , B i t t i u m r_. s u b p la n a tu m and A d o n to r h in a c y c l i a f o r th e C a r d i t a a s s o c i a t i o n . The r e m a in in g s p e c i e s do n o t co n fo rm t o any s i n g l e a s s o c i a t i o n d i s t r i b u t i o n . Some may be c o n c e n t r a t e d i n a l l o r a p a r t o f a s i n g l e a s s o c i a t i o n , b u t o t h e r s a r e p ro m in e n t i n more t h a n one a s s o c i a t i o n . Some s p e c i e s a r e p r e s e n t a t n e a r l y e v e r y s a m p lin g s t a t i o n . I t s h o u l d be a p p a r e n t from t h e e x a m i n a t i o n o f t h e s e f i g u r e s t h a t no two s p e c i e s h a v e e x a c t l y t h e same d i s t r i b u t i o n w ith r e s p e c t t o d e p t h and s e d im e n t g r a i n s i z e . The a p p a r e n t d i f f e r e n c e b e tw e e n d i s t r i b u t i o n a l p a t t e r n s o f s p e c i e s would b e e n h a n c e d i f th e s i m u l t a n e o u s c o n s i d e r a t i o n o f an a d d i t i o n a l number o f v a r i a b l e s w ere u n d e r t a k e n . Summary D i s c u s s i o n D i s t r i b u t i o n of s e l e c t e d s p e c i e s , a s w e l l a s o f th e t h r e e m a jo r b e n t h i c a s s o c i a t i o n s on t h e S a n ta B a r b a r a s h e l f , h a s b een p l o t t e d a g a i n s t a s i n g l e e n v i r o n m e n t a l v a r i a b l e , d e p t h , and a g a i n s t two v a r i a b l e s s i m u l t a n e o u s l y , d e p t h and m ed ian d i a m e t e r o f s e d im e n t g r a i n s . The t h r e e a s s o c i a t i o n s h av e d i f f e r e n t b u t o v e r l a p p i n g d i s t r i b u t i o n s w i t h r e s p e c t t o t h e s i n g l e v a r i a b l e ; th e y a r e i s o l a t e d when d e l i m i t e d by 192 th e two v a r i a b l e s . S p e c i e s d i s t r i b u t i o n s y i e l d a s e r i e s o f h i g h l y com plex p a t t e r n s . I n g e n e r a l , some s p e c i e s hav e r a n g e s l i m i t e d by d e p t h a l o n e o r b y b o th d e p t h and s e d im e n t , and c o n fo rm c l o s e l y t o t h e d i s t r i b u t i o n o f t h e a s s o c i a t i o n s w ith w h ic h t h e y have b e e n d e s c r i b e d a s a f f i l i a t e d . O th e r s ra n g e more w i d e l y ; some a re p r o m in e n t i n more t h a n one a s s o c i a t i o n and a few a r e p r e v a l e n t on t h e s h e l f . P r e v io u s d e s c r i p t i o n s o f t h e s e t h r e e b e n t h i c a s s o c i a t i o n s have te n d e d t o e m p h a siz e t h e i r d i f f e r e n c e s , e x c l u d i n g c o n s i d e r a t i o n o f s i m i l a r i t i e s i n t h e i r f a u n a l c o m p o s i t i o n s . C h a r a c t e r i s t i c d i f f e r e n c e s do e x i s t ( s e e A p p e n d ix D ) . How e v e r , th e t e n d e n c y t o d e s c r i b e a s s o c i a t i o n s a s d i s c r e t e ob s c u r e s th e p r e s e n c e o f common s p e c i e s . The p r a c t i c e o f i n c l u d i n g th e c o n s p ic u o u s f a u n a l e l e m e n t s i n i l l u s t r a t i o n s o f " t y p i c a l " a r e a l p l o t s ( b a s e d on s e l e c t e d c o n s p ic u o u s s p e c i e s ) h e i g h t e n s t h i s p o r t r a y a l o f d i s s i m i l a r i t y , s i n c e s p e c i e s w h ic h a r e p r e s e n t b u t n o t d i s t i n c t i v e l y c o n s p ic u o u s may b e o v e r lo o k e d . The i n v e s t i g a t i o n o f t h r e e b e n t h i c a s s o c i a t i o n s r e p o r t e d i n t h i s s e c t i o n o f f e r s an exam ple s u p p o r t in g t h e s e g e n e r a l i z a t i o n s . The d ia g r a m m a tic r e p r e s e n t a t i o n o f th e i n h a b i t a n t s o f a t y p i c a l o n e - q u a r t e r s q u a r e m e te r o f b o tto m s o i l i n th e L i s t r i o l o b u s a s s o c i a t i o n p r e s e n t e d by B a r n a r d and H artm an (1 9 5 9 , F i g u r e 1; a l s o A p p en d ix F i g u r e D-15) d i d n o t i n c l u d e s i x s p e c i e s w h ich t h e s e a u t h o r s c o n s i d e r e d p r o m in e n t members o f t h i s a s s o c i a t i o n ( T a b le 1 , p . 6 ) . T h e se a r e 193 C e r a t o c e p h a l a £ . a m e ric a n a (mean d e n s i t y , 76/m3 ) , M arphysa s p . (40/m 2 ) , H esp ero n o e s p . (56/m 3 ) , S t e r n a s p i s f o s s o r (16/m 2 ) , A m phiodia u r t i c a (98/m 3 ) and S a x i c a v e l l a p a c i f i c a (93/m 2 ) . T o g e th e r th e y r e p r e s e n t a p o p u l a t i o n o f 370 s p e c i mens p e r s q u a re m e t e r . The o m is s io n o f A m phiodia u r t i c a i s p a r t i c u l a r l y n o te w o r th y . W hile t h e a d d i t i o n o f th e a p p r o p r i a t e number ( 2 4 ) of sym bols r e p r e s e n t i n g t h i s s p e c i e s w ould n o t a l t e r th e g e n e r a l a p p e a ra n c e o f t h i s i l l u s t r a t i o n , i t would add a se co n d common e le m e n t ( P e c t i n a r i a c a l i f o r n i - e n s i s i s t h e f i r s t ) a l s o fo u n d i n th e i l l u s t r a t i o n s o f th e o p h i u r o i d a s s o c i a t i o n s ( F i g u r e s 6, 7 , and 8, B a rn a rd and Z ie s e n h e n n e , 1961; a l s o s e e A p p en d ix F i g u r e s D - l l , D-12 and D -1 3 ). The mean d e n s i t y o f A m phiodia u r t i c a , 98/m2 , i s n e a r l y a f o u r t h of t h a t i n t h e A m p h io d ia- C a r d i t a a s s o c i a t i o n (408/m 2 ) and a lm o st o n e - h a l f t h a t i n th e A m phioplus h e x a c a n th u s a s s o c i a t i o n . The p r e s e n c e o f i m p o r t a n t s p e c i e s su ch a s t h i s s h o u ld n o t be o b s c u re d i n th e p r o c e s s o f f a u n a l d e s c r i p t i o n . Ten s p e c i e s ( F i g u r e s 1 1 -5 4 ) o c c u r r i n g i n one o r b o th o f th e o t h e r two m a jo r b e n t h i c a s s o c i a t i o n s o f t h i s a r e a and i n th e L i s t r i o l o b u s a s s o c i a t i o n a re n o t i n c l u d e d i n th e l i s t o f t h e p ro m in e n t s p e c i e s o f th e L i s t r i o l o b u s a s s o c i a t i o n ( T a b le 1, B a rn a rd and H artm an , 1 9 5 9 ). M is s in g a r e t h e p r e v a l e n t s p e c i e s S p io p h a n e s m i s s i o n e n s i s ( F i g u r e 2 0 ) , P r i o n o s p i o p i n n a t a ( F ig u r e 2 1 ) , A m p h ip h o lis sq u a m a ta ( F i g u r e 22) and A x in o p s id a s e r r i c a t a ( F ig u r e 4 8 ) . The f a i l u r e to 194 i n c l u d e t h e s e and th e w ide r a n g i n g p o l y c h a e t e T e r e b e l l i d e s s tr o e m i ( F i g u r e 45) t e n d s to m in im iz e t h o s e s i m i l a r i t i e s t h a t do e x i s t b e tw e e n th e L i s t r i o l o b u s a s s o c i a t i o n and a d j a c e n t a s s o c i a t i o n s . Added e x a m p le s a r e fo u n d i n t h e p u b l i s h e d d e s c r i p t i o n s o f th e N o t h r i a - T e l l i n a a s s o c i a t i o n and th e A m p h io d ia - C a r d i t a a s s o c i a t i o n ( s e e A p p en d ix D ). The p r e v a l e n t o p h i u r o i d A m p h ip h o lis sq u a m a ta i s o m i t t e d from th e d e s c r i p t i o n o f t h e N o t h r i a - T e l l i n a a s s o c i a t i o n e v e n th o u g h i t i s b r o a d l y d i s t r i b u t e d t h e r e ( F i g u r e 2 2 ) . F u r t h e r , a l t h o u g h A m p h io d ia u r t i c a i s a b s e n t fro m o n ly 2 o f 18 s a m p lin g l o c a t i o n s i n t h i s a s s o c i a t i o n ( F i g u r e 4 6 ) , B a r n a r d r s i l l u s t r a t i o n s o f t h i s a s s o c i a t i o n a r e t o t a l l y d e v o id o f o p h i u r o i d s ( B a r n a r d , 1963; F i g u r e s 1, 2 and 3; a l s o s e e A p p en d ix F i g u r e s D -1 6 , D-17 and D - 1 8 ) . S ix o t h e r s p e c i e s B a r n a r d c o n s i d e r e d p r o m in e n t f a u n a l e le m e n ts o f one or b o th o f th e a d j a c e n t c o m m u n itie s and a l s o o c c u r r i n g i n sa m p le s fro m th e N o t h r i a - T e l l i n a a s s o c i a t i o n a r e o m i t t e d fro m i t s d e s c r i p t i o n . The same s i t u a t i o n o c c u r s w i t h f o u r s p e c i e s i n th e A m p h io d ia - C a r d i t a a s s o c i a t i o n . Of th e 44 s p e c i e s i l l u s t r a t e d i n F i g u r e s 11 t o 54, 38 ( 8 6 .5 p e r c e n t ) o f t h o s e th a t o c c u r i n t h e L i s t r i o l o b u s a s s o c i a t i o n , 33 ( 7 5 .0 p e r c e n t ) t h a t o c c u r i n t h e N o t h r i a - T e l l i n a a s s o c i a t i o n and 36 ( 8 2 .0 p e r c e n t ) t h a t o c c u r i n th e A m p h io d ia - C a r d i t a a s s o c i a t i o n a l s o o c c u r i n one or b o t h o f t h e a d j a c e n t a s s o c i a t i o n s . The t r a d i t i o n a l p r o c e d u r e s u s e d t o d e s c r i b e b e n t h i c ,■ 195 a s s o c i a t i o n s ( T h o r s o n , 1957) i n c l u d i n g t h a t u se d i n t h e p r e v i o u s d e s c r i p t i o n s o f th e b e n t h i c i n v e r t e b r a t e m a c ro f a u n a o f th e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f - - h a s o f t e n e m p h a siz e d f a u n i s t i c d i s s i m i l a r i t i e s a t t h e e x p e n se o f f a u - n i s t i c s i m i l a r i t i e s . The u se o f m ethods b a s e d on more ob j e c t i v e c r i t e r i a w ould be h e l p f u l i n o v erco m in g t h i s s h o r t com ing. S t a t i s t i c a l s p e c i e s g r o u p in g t e c h n i q u e s a r e b a s e d on such c r i t e r i a . The r e s u l t s o f th e a p p l i c a t i o n o f two o f t h e s e t e c h n i q u e s a r e exam ined i n t h e n e x t s e c t i o n . S p e c i e s G ro u p in g S p e c i e s g r o u p s , s p e c i e s a s s o c i a t e d s t a t i s t i c a l l y , can be r e c o g n i z e d i n th e d a t a fro m a l a r g e sam ple s e t by th e a p p l i c a t i o n o f com puter t e c h n i q u e s . The m ethods p r o grammed f o r t h i s p u rp o s e a r e b a s e d on e i t h e r o f two d i f f e r e n t b a s i c c r i t e r i a - ~ t h e o c c u r r e n c e v e r s u s t h e n o n -o c c u rre n c e o f s p e c i e s i n th e s a m p le s o f a sam p le s e t o r t h e s p e c i e s p o p u l a t i o n d e n s i t i e s as e s t i m a t e d by th e s a m p le s o f a s a m p l e - s e t . The two m e th o d s, th e R e c u r r e n t Group A n a l y s i s ( F a g e r , 1957; F a g e r and McGowan, 1963) and t h e 3NITSYS c l u s t e r a n a l y s i s ( R o h lf and K is h p a u g h , 1 9 6 6 ), s e l e c t e d f o r t h i s i n v e s t i g a t i o n e x e m p lif y th e two d i f f e r i n g s t a t i s t i c a l a p p r o a c h e s t o s p e c i e s g r o u p in g . R e c u r r e n t Group A n a l y s i s R e c u r r e n t g ro u p a n a l y s i s was a c c o m p lis h e d by th e p ro g ra m REGROUP ( s e e REGROUP, D a ta and E l e c t r o n i c D a ta 196 P r o c e s s i n g s e c t i o n ) u t i l i z i n g t h e H o n ey w ell 800 C o m p u ter. D e t e r m i n a t i o n o f an in d e x o f a f f i n i t y b e tw e e n a l l s p e c i e s p a i r s i s p r e r e q u i s i t e to t h e g ro u p in g p r o c e s s . The i n d e x o f a f f i n i t y i s d e f i n e d as th e g e o m e t r ic mean o f t h e p r o p o r t i o n o f j o i n t o c c u r r e n c e s as c o r r e c t e d f o r sa m p le s i z e . To be fo rm ed a r e c u r r e n t group m u st s a t i s f y th e a r b i t r a r y r e q u i r e m e n ts d e t a i l e d b y th e a u t h o r s o f t h i s t e c h n i q u e ( F a g e r , 1957; F a g e r and McGowan, 196 3 ) . The d a t a fro m th e 1 7 6 -sa m p le s e t w ere a n a ly z e d by t h i s m e th o d ; i n s u b s e q u e n t r u n s two s u b s e t s o f t h e s e d a t a w ere a n a l y z e d f o r r e c u r r e n t g r o u p s . S e p a r a t e i n p u t d e c k s were p r e p a r e d by t h e H-800 d i r e c t e d by t h e u t i l i t y p ro g ram w r i t t e n b y th e a u t h o r f o r t h i s p u r p o s e . The s i z e o f c o r e s t o r a g e o f c o m p u ter l i m i t e d t h e number o f s p e c i e s c o n s i d e r e d to 2 0 0 ; th e s p e c i e s s e l e c t e d w ere t h e to p 200 ra n k e d by f r e q u e n c y in t h e 1 7 6 -sam p le s e t . I n th e i n i t i a l ru n t h e a s s i g n e d v a l u e o f th e a f f i n i t y i n d e x was s e t a t 0.500 and th e maximum a l l o w a b l e com b i n a t i o n s to be c o n s i d e r e d was s e t a t 2 0 ,0 0 0 ( i n p u t as th e l o g a r i t h m 4 . 3 0 1 ) . However, t h e number o f c o m b in a tio n s i n t h e d a t a , c a . 8 2 4 ,1 0 0 ( l o g a r i t h m , 5 . 9 1 6 ) , g r e a t l y e x c e e d e d t h e number a l l o w e d ; and th e c o m p u ter t e r m i n a t e d t h e p r o c e s s i n g by an e r r o r r o u t i n e . The v a lu e o f th e c o n t r o l l i n g l o g a r i t h m was r a i s e d above t h a t o f th e number o f co m b in a t i o n s i n t h e d a t a and th e p ro g ra m r e - r u n . The pro g ram s u c c e s s f u l l y c o m p le te d th e i n p u t p h a s e ; made a f f i n i t y 197 c a l c u l a t i o n s and m a t r i x c o n s t r u c t i o n ; o u t p u t s p e c i e s l i s t ra n k e d by a f f i n i t i e s ; o u tp u t th e m a t r i x ; and e n t e r e d th e g ro u p in g s e q u e n c e . However, th e com puter had s t i l l f a i l e d to f i n d th e f i r s t s p e c i e s g ro u p 30 m in u te s a f t e r th e b e g i n n in g o f th e i n i t i a t i o n o f th e g ro u p in g p r o c e s s , and t h e p r o gram was t e r m i n a t e d from th e c o n s o le . The number o f com bin a t i o n s t h e com puter was c o n s i d e r i n g was to o h ig h to c o m p lete th e pro g ram i n a r e a s o n a b l e l e n g t h o f tim e . An i d e n t i c a l d i f f i c u l t y was e n c o u n te r e d i n th e i n i t i a l r u n s made u s in g s u b s e t s o f th e t o t a l d a t a a s i n p u t . R e s u l t s c o u ld be o b t a i n e d o n ly by r a i s i n g th e a s s ig n e d a f f i n i t y in d e x v a lu e to 0 .6 5 0 , t h u s s u b s t a n t i a l l y r e d u c in g th e number o f c o m b in a tio n s t o be c o n s id e r e d by th e c o m p u te r; th e a llo w a b le maximum number o f c o m b in a tio n s c o u ld th e n be re d u c e d to 5 0 ,0 0 0 ( l o g a r i t h m , 4 . 6 9 9 ) . T h is p ro b le m e l u c i d a t e s a c h a r a c t e r i s t i c o f th e d a t a , t h e m arked te n d e n c y o f a h ig h number o f s p e c i e s to c o - o c c u r w ith many o f th e o t h e r s p e c i e s a t or above th e in d e x o f a f f i n i t y s u g g e s t e d by F ag er ( 1 9 5 7 ) . W ith t h e i n dex o f a f f i n i t y s e t a t 0 .5 0 0 a t o t a l o f 89 o f t h e 200 to p ra n k e d s p e c i e s had a f f i n i t y w i t h 1 or more s p e c i e s ; th e f i r s t ra n k e d s p e c i e s , A m phiodia u r t i c a , had a f f i n i t i e s w i t h 88 o t h e r s p e c i e s i n th e 1 7 6 -sa m p le s e t . The 89 s p e c i e s w ith a f f i n i t i e s a v e ra g e d 3 0 .1 a f f i n i t i e s p e r s p e c i e s . When th e a s s i g n e d v a lu e was s e t a t 0 .6 5 0 o n ly 48 s p e c i e s had 1 o r more a f f i n i t i e s w ith o t h e r s p e c i e s . P r i o n o s p i o p i n n a t a 198 ra n k e d f i r s t w i t h 29; t h e mean f o r s p e c i e s w i t h a f f i n i t i e s was 8 .8 p e r s p e c i e s . The M a in la n d S h e l f R e c u r r e n t G roups The to p 200 s p e c i e s a s ra n k e d b y f r e q u e n c y i n t h e 1 7 6 -sa m p le s e t w ere a n a ly z e d by t h e r e c u r r e n t g ro u p m eth o d . O nly 48 s p e c i e s showed a f f i n i t y w i t h o t h e r s p e c i e s when th e a f f i n i t y i n d e x was s e t a t 0 .6 5 0 ; t h e s e i n c l u d e d 23 p o l y - c h a e t e s , 18 c r u s t a c e a n s , 2 e c h in o d e r m s , 2 m o llu s k s and 3 fro m o t h e r p h y l e t i c g r o u p s . A l l o f th e s p e c i e s l i s t e d i n T a b le 4 a r e i n c l u d e d among t h e s e 48 s p e c i e s . T w e n t y - e i g h t o f t h e s e s p e c i e s c o u ld be arran g ed i n 7 g r o u p s ; t h e r e m a in in g 20 s p e c i e s had a f f i n i t i e s w i t h some, b u t n o t a l l , o f t h e members o f one o r t h e o t h e r o f t h e s e g r o u p s . T a b le 10 p r e s e n t s th e 7 r e c u r r e n t g r o u p s l i s t i n g ( l ) t h e s p e c i e s c o n s t i t u t i n g e a c h g r o u p , ( 2 ) th e s p e c i e s show ing a f f i n i t y to a p a r t i c u l a r g ro u p a l o n e , ( 3 ) t h e num b e r o f o c c u r r e n c e s o f e a c h s p e c i e s i n t h e 1 7 6 -sa m p le s e t , (4 ) th e number o f a f f i n i t i e s th e s p e c i e s h a s w i t h o t h e r s p e c i e s , and ( 5 ) t h e s p e c i e s common t o T a b le 4 , a s i n d i c a t e d b y an a s t e r i s k . The i n t e r - r e l a t i o n s h i p o f t h e s e g ro u p s can be shown d i a g r a m m a t i c a l l y . I n t e r - g r o u p c o n n e c t i o n s i n d i c a t e t h a t t h e s p e c i e s i n one g ro u p have some a f f i n i t i e s w ith t h e s p e c i e s i n a n o t h e r g r o u p . The r e l a t i o n s h i p s o f th e 7 g ro u p s a r e shown i n F i g u r e 55; th e f r a c t i o n s a r e t h e r a t i o s o f th e o b s e rv e d i n t e r - g r o u p a f f i n i t i e s 199 T a b le 10. The R e c u r r e n t G roups o f t h e M a in la n d S h e l f B ased on th e A n a l y s i s o f th e 176-S am ple S e t , I . A. = 0 .6 5 0 . GROUP I : * P r i o n o s p i o p i n n a t a (P ) 159 29 * P h o lo e g l a b r a (P ) 124 28 ^A m phiodia u r t i c a (E ) 153 26 * P e c t i n a r i a c a l i f o r n i e n s i s (P ) 131 26 G n a t h i a c r e n u l a t i f r o n s (C) 92 18 * P a r a o n i s g r a c i l i s (P ) 108 15 * A x in o p s id a s e r r i c a t a (M) 92 14 T e r e b e l l i d e s s t r o e m i (P) 103 14 * G ly c e r a c a p i t a t a (P ) 94 13 * A m p e lisc a b r e v i s i m u l a t a (C) 101 13 A s s o c i a t e d w i t h Group I : A r i c i d e a s u e c i c a (P ) 84 1 A x i o t h e l l a r u b r o c i n c t a (P ) 87 1 P a ra p h o x u s r o b u s t u s (C) 73 1 C h l o e i a p i n n a t a (P ) 64 1 * A m p e lisc a c r i s t a t a CC) 89 2 * G l o t t i d i a a l b i d a (O) 91 2 G o n ia d a b r u n n e a (P ) 114 7 * H a p l o s c o l o p lo s e l o n g a t u s (P ) 105 5 L a o n ic e c i r r a t a (P ) 96 3 * L u m b r in e r is c r u z e n s i s (P ) 92 3 200 Table 10 (Cont.) R e c u r r e n t G ro u p s O c c u r r e n c e A f f i n i t i e s A s s o c i a t e d w i t h G ro u p I ( C o n t . ) : * S p i o p h a n e s m i s s i o n e n s i s (P ) 107 7 S t h e n e l a n e l l a u n i f o r m i s (P ) 84 2 * N e p h ty s s p . (P ) 90 2 H a lio p h a s m a g e m i n a t a (C) 93 9 * M e ta p h o x u s f r e q u e n s (C) 73 7 N e p h ty s f e r r u g i n e a (P ) 77 • 5 GROUP I I : * n e m e r t e a n unknown (O) 150 20 * P r i o n o s p i o m a lm g re n i (P ) 148 17 * A m p h ip h o lis s q u a m a ta (E ) 136 13 * t a n a i d unknown (C ) 105 13 * o s t r a c o d unknown (C ) 109 10 * T h a ry x t e s s e l a t a (P ) 105 7 A s s o c i a t e d w i t h G ro u p I I : * A m p e lis c a c r i s t a t a (C) 89 2 * G l o t t i d i a a l b i d a (O) 91 2 G o n ia d a b r u n n e a (P ) 114 7 * H a p l o s c o l o p l o s e l o n g a t u s ( P ) 105 5 L a o n ic e c i r r a t a (P ) 96 3 * L u m b r i n e r i s c r u z e n s i s ( P ) 92 3 * S p i o p h a n e s m i s s i o n e n s i s (P ) 107 7 S t h e n e l a n e l l a u n i f o r m i s ( P ) 84 2 2 0 1 Table 10 (Cont.) A s s o c i a t e d w i t h G roup I I ( C o n t . ) : * N ep h ty s s p . (P ) 90 2 H a lio p h a sm a g e m in a ta (C) 93 9 GROUP I I I : * H e te ro p h o x u s o c c u l a t u s (C) 97 17 * P a ra p h o x u s s i m i l i s (C) 76 12 * P a ra p h o x u s b i c u s p i d a t u s (C) 77 6 A m p e lis c a p a c i f i c a (C) 76 12 A s s o c i a t e d w i t h Group I I I : H a lio p h a s m a g e m in a ta (C) 93 9 *M etaphoxus f r e q u e n s (C) 73 7 N ic ip p e tu m id a (C) 50 2 N em ocardium c e n t i f i l o s u m (M) 53 1 E u d o r e l l a A (C ) 63 2 N e p h ty s f e r r u g i n e a (P ) 77 5 GROUP IV: * C o s s u r a C a n d id a (P ) ? ? * S t e r n a s p i s f o s s o r (P ) 95 10 GROUP V: * A r i c i d e a l o p e z i (P) 80 3 * nem atode unknown (O) 91 4 A s s o c i a t e d w i t h Group V: M ed io m astu s c a l i f o r n i e n s i s (P ) 65 1 202 Table 10 (Cont.) R e c u r r e n t G roups GROUP VI: D i a s t y l i d a e unknown (C) A m p e lis c a p u g e t i c a (C) GROUP V II: brown o s t r a c o d (C) r e c t a n g u l a r o s t r a c o d (C) O c c u r re n c e A f f i n i t i e s 70 69 46 34 4 6 1 1 * = s p e c i e s common t o T a b le 4 . Figure 55 A D ia g ra m m a tic R e p r e s e n t a t i o n o f th e I n t e r - r e l a t i o n s h i p o f th e R e c u r r e n t G ro u p s o f t h e M a in la n d S h e l f B ased on I n t e r - Group A f f i n i t i e s . The f r a c t i o n s a r e t h e r a t i o s o f th e o b s e r v e d i n t e r - g r o u p a f f i n i t i e s t o th e maximum p o s s i b l e i n t e r ■ g ro u p a f f i n i t i e s . 20 3 GROUP GROUP 3/12 27 60 GROUP T X 1/20 2/1 20, 2/8 GROUP m GROUP 6/20 GROUP HI w o ■ p * Figure 55 205 ( s p e c i e s - p a i r s w i t h a f f i n i t i e s ) t o t h e maximum p o s s i b l e s u c h a f f i n i t i e s . The f i r s t g ro u p , Group I , d e r i v e d by t h i s m ethod o f a n a l y s i s i s an a s se m b la g e o f 10 s p e c i e s - - 6 p o l y c h a e t e s , 2 c r u s t a c e a n s (1 am phipod and 1 i s o p o d ) , 1 o p h i u r o i d and 1 p e le c y p o d ( T a b le 1 0 ) . A m phiodia u r t i c a , an o p h i u r o i d e c h in o d e rm , i s th e f i r s t ra n k e d s p e c i e s by p o p u l a t i o n d e n s i t y ( 3 5 9 .1 s p e c im e n s p e r s q u a re m e t e r ) and t h e t h i r d - r a n k e d s p e c i e s by f r e q u e n c y (1 5 3 o c c u r r e n c e s o r 87 p e r c e n t ) i n th e 1 7 6 -sa m p le s e t . T h is g ro u p a l s o i n c l u d e s f o u r f r e q u e n t l y e n c o u n t e r e d and a b u n d a n t p o l y c h a e t e s : P r i o n o s p i o p i n n a t a ( l l t h - r a n k e d b y d e n s i t y , 2 n d -ra n k e d by f r e q u e n c y ) , P e c t i n a r i a c a l i f o r n i e n s i s ( 1 0 t h , 6 t h ) , P h o lo e g l a b r a ( 1 3 t h , 7 t h ) , and P a r a o n i s g r a c i l i s ( 1 9 t h , 1 0 t h ) . The o t h e r two p o l y c h a e t e s , T e r e b e l l i d e s s tr o e m i and G l y c e r a c a p i t a t a , a r e somewhat l e s s p r o m in e n t s t a t i s t i c a l l y . The am phipod c r u s t a c ean A m p e lis c a b r e v i s i m u l a t a i s r a n k e d 1 5 th b y d e n s i t y ( 3 5 .7 /m 2 ) and 1 6 th by f r e q u e n c y ; A x in o p s id a s e r r i c a t a , a p e le c y p o d m o l l u s k , r a n k s 7 t h i n ab u n d an ce ( 5 4 .7 / m 2 ) b u t o n ly 2 2 . 5 t h by f r e q u e n c y . The o t h e r s p e c i e s , th e is o p o d G n a t h i a c r e n u l a t i f r o n s , i s t h e l o w e s t - r a n k e d o f t h e 10 s p e c i e s o f t h i s g ro u p i n te r m s o f b o t h p o p u l a t i o n d e n s i t y and f r e q u e n c y . S i x t e e n s p e c i e s a r e a s s o c i a t e d w i t h G roup I on th e b a s i s o f t h e i r a f f i n i t y w i t h one o r more o f t h e s p e c i e s i n t h i s g r o u p . P o u r s p e c i e s - - t h e p o l y c h a e t e s A r i c i d e a s u e c i c a , 206 A x i o t h e l l a r u b r o c i n c t a , and C h l o e i a p i n n a t a and t h e amphipod P a ra p h o x u s r o b u s t u s — e a c h have a s i n g l e a f f i n i t y w i t h a s p e c i e s i n t h i s g r o u p . Of th e 12 a d d i t i o n a l s p e c i e s n i n e (7 p o l y c h a e t e s , an am phipod, and t h e i n a r t i c u l a t e b r a c h i o - pod G l o t t i d i a a l b i d a ) a r e a s s o c i a t e d w i t h Group I I and t h r e e s p e c i e s (2 c r u s t a c e a n s and a p o l y c h a e t e ) a r e a s s o c i a te d w i t h Group I I I ( T a b le 1 0 ). Group I h a s m u l t i p l e i n t e r - g r o u p c o n n e c t i o n s w i t h a l l m in o r g ro u p s e x c e p t G roup V and Group V II ( F i g u r e 5 5 ); i t s h a r e s o n ly a s i n g l e s p e c i e s - p a i r a f f i n i t y w i t h Group V and none w ith G roup V I I , w h ic h l a c k s i n t e r - g r o u p c o n n e c t i o n s . G roup I i s m ost i n t i m a t e l y bound to G roup IV; f o u r t e e n o f t h e p o s s i b l e 20 s p e c i e s - p a i r a f f i n i t i e s (7 0 per c e n t ) b e tw e e n t h e s e two g ro u p s o c c u r . Group I i s a l s o r a t h e r c l o s e l y l i n k e d to G roup I I I (2 4 o f 40 [60 p e r c e n t ] o f p o s s i b l e s p e c i e s - p a i r s h a v e a f f i n i t i e s ) and G roup I I (27 o f 60 [45 p e r c e n t] o f th e p o s s i b l e p a i r s ) . I t i s l i n k e d by 6 o f a p o s s i b l e 20 s p e c i e s - p a i r a f f i n i t i e s (30 p e r c e n t ) t o Group V I. The s i n g l e a f f i n i t y s h a r e d by Groups I and V i s b u t 5 p e r c e n t o f th o s e p o s s i b l e b e tw e e n t h e s e two g r o u p s . Group I was c o l l e c t e d a s a u n i t i n 29 s a m p le s , and a t l e a s t 9 members o f t h i s group w e re c o l l e c t e d a t 51 s a m p lin g l o c a t i o n s o u t o f 176 (29 p e r c e n t ) . S i x f a u n a l e l e m e n t s c o m p ris e Group I I - - 2 p o l y c h a e t e s , 2 c r u s t a c e a n s ( 1 t a n a i d and 1 o s t r a c o d ) , 1 o p h i u r o i d and 1 n e m e r te a n (T a b le 1 0 ) . The two c r u s t a c e a n s 207 and t h e n e ra e rte a n can b e r e g a r d e d a s s p e c i e s o n ly fro m a s t a t i s t i c a l s t a n d p o i n t . One o f t h e p o l y c h a e t e s , P r i o n o s p i o m a lm g r e n i, i s t h e 4 t h - r a n k e d s p e c i e s i n th e 1 7 6 -sa m p le s e t on t h e b a s i s o f b o t h p o p u l a t i o n d e n s i t y ( 9 2 .8 /m 3 ) and f r e q u e n c y (1 4 8 o c c u r r e n c e s o r 84 p e r c e n t ) ; th e o t h e r , T h a ry x t e s s e l a t a , i s 8 t h - r a n k e d by d e n s i t y ( 5 3 .6 /m 2 ) and 1 3 th - r a n k e d b y f r e q u e n c y (1 0 5 o c c u r r e n c e s o r 59 p e r c e n t ) . The e c h in o d e rm A m p h ip h o lis sq u a m a ta i s ra n k e d 1 2 th by d e n s i t y ( 3 9 .5 /m 3 ) and 5 t h by f r e q u e n c y (1 3 6 o c c u r r e n c e s o r 77 p e r c e n t ) . I n a d d i t i o n t o t h e n i n e s p e c i e s (7 p o l y c h a e t e s , 1 c r u s t a c e a n and 1 b r a c h i o p o d ) a s s o c i a t e d w i t h b o t h Group I and Group I I , t h r e e s p e c i e s have a f f i n i t i e s w i t h Group I I and Group I I I ( T a b le 1 0 ) . G roup I I was c o l l e c t e d a t 45 s t a t i o n s ( 2 5 .5 p e r c e n t ) . I t h a s i n t e r - g r o u p c o n n e c t i o n s w i t h two o t h e r g ro u p s b e s i d e s G roup I ; o f 12 p o s s i b l e c o n n e c t i o n s w i t h Group V, t h r e e (2 5 p e r c e n t ) o c c u r , w h ile 2 o f th e 12 p o s s i b l e c o n n e c t i o n s ( 1 6 . 7 p e r c e n t ) b e tw e e n Group I I and Group VI a r e p r e s e n t ( F i g u r e 5 5 ) . The t h i r d g ro u p ( I I I ) c o n s i s t s e n t i r e l y o f c r u s t a c e a n s , 4 am phipods ( T a b le 1 0 ) . S i x s p e c i e s a r e a s s o c i a t e d w i t h G roup I I I , o f w h ic h o n e , t h e is o p o d H a lio p h a s m a gem i n a t a , a l s o h a s a f f i n i t y w i t h G roups I and I I . Two o t h e r s p e c i e s , t h e amphipod M etap h o x u s f r e q u e n s and t h e p o l y - c h a e t e N e p h ty s f e r r u g i n e a , a r e a s s o c i a t e d w i t h G roup I . The r e m a i n in g 3 s p e c i e s , 2 c r u s t a c e a n s ( a n amphipod and a cum acean) and 1 p e l e c y p o d , have a f f i n i t i e s o n ly w i t h Group 208 I I I . Group I I I , i n a d d i t i o n t o i t s c l o s e c o n n e c t i o n w i t h Group I , i s c o n n e c te d by 2 o f 8 s p e c i e s - p a i r a f f i n i t i e s (2 5 p e r c e n t ) w i t h Group IV and 1 o f 8 p a i r - g r o u p s ( 1 2 . 5 p e r c e n t ) w i t h Group VI ( F i g u r e 5 5 ) . Group I I I was c o l l e c t e d a t 48 ( 2 7 . 3 p e r c e n t ) s t a t i o n s . Two p o l y c h a e t e s , C o s s u r a C a n d id a and S t e r n a p s i s f o s s o r , c o m p rise Group IV . No o t h e r s p e c i e s a r e a s s o c i a t e d w i t h t h i s g ro u p ( T a b le 1 0 ) . I t i s c o n n e c te d o n ly w i t h G roups I and I I I ( F i g u r e 5 5 ) . Group IV was c o l l e c t e d i n 69 ( 3 9 . 2 p e r c e n t ) s a m p le s . G roup V i n c l u d e s t h e p o l y c h a e t e A r i c i d e a l o p e z i and th e s t a t i s t i c a l s p e c i e s T ,n em atode unknown” (T a b le 1 0 ) . Be c a u s e o f t h e s m a l l s i z e o f m o st m a r in e n e m a to d e s and c o n s i d e r i n g t h e mesh s i z e o f t h e s c r e e n u s e d t o s i e v e th e sam p l e s c o l l e c t e d i n t h i s i n v e s t i g a t i o n , i t i s l i k e l y t h a t t h i s c a t e g o r y , te rm e d ”n em ato d e u n k n o w n ,” c o n t a i n s few s p e c i e s . M ed io m astu s c a l i f o r n i e n s i s , a p o l y c h a e t e , i s a s s o c i a t e d b y a f f i n i t y w i t h t h i s g r o u p . Group V i s l e s s i n t i m a t e l y c o n n e c te d t o t h e o t h e r g ro u p s t h a n any g ro u p e x c e p t V I I , w h ich l a c k s t h e s e c o n n e c t i o n s e n t i r e l y . O n ly 4 o f 32 ( 1 2 .5 p e r c e n t ) p o s s i b l e s p e c i e s - p a i r a f f i n i t i e s e x i s t w i t h t h e two g r o u p s , I and I I , t o w h ic h i t i s c o n n e c te d ( F i g u r e 5 5 ) . Group V was c o l l e c t e d a t 60 ( 3 4 . 2 p e r c e n t ) s a m p lin g l o c a t i o n s . Two c r u s t a c e a n s , a cum acean and an am phipod, make up G roup V I. ”D i a s t y l i d a e unknown” i s t h e t e n t a t i v e name 209 g i v e n to a s i n g l e s p e c i e s o f cum acean ( p e r s . comm. R. G iv e n ) . Group VI i s l i n k e d t o 3 g r o u p s C l, I I , and I I I ) and was c o l l e c t e d i n 49 s a m p le s . Group V II c o n s i s t s o f two t e n t a t i v e l y named t y p e s o f o s t r a c o d c r u s t a c e a n s , p r o b a b l y two d i s t i n c t s p e c i e s . A t t h e h ig h a f f i n i t y l e v e l ( 0 . 6 5 0 ) em ployed i n t h i s a n a l y s i s th e s e v e n th g ro u p l a c k s any i n t e r - g r o u p c o n n e c t i o n s ( F i g u r e 5 5 ) . Group V II was c o l l e c t e d i n 27 ( 1 5 . 2 p e r c e n t ) sam p l e s . T y p i c a l l y s a m p le s c o n t a i n members o f more t h a n one r e c u r r e n t g r o u p ; i n f a c t , m ost f r e q u e n t l y more th a n one c o m p le te g ro u p i s c o l l e c t e d i n a s i n g l e s a m p le . Of th e 176 s a m p le s s t u d i e d 2 7 .8 p e r c e n t ( 4 9 ) c o n t a i n e d b u t a s i n g l e c o m p le te g r o u p ; 5 5 .1 p e r c e n t ( 9 7 ) c o n t a i n e d two o r more g r o u p s ; 1 7 .1 p e r c e n t ( 3 0 ) la c k e d any c o m p le te g ro u p . G roups d o , t h e n , o c c u r i n c o m b i n a t i o n . T h e re a r e se v e n f a c t o r i a l (71 = 5040) p o s s i b l e c o m b in a tio n s o f th e 7 g ro u p s, b u t o n ly 49 o f t h e s e w ere e n c o u n t e r e d i n th e 176 sa m p le s s t u d i e d . G roup I was i n v o l v e d i n 18 o f t h e s e 49 c o m b in a t i o n s ; G roup I I , i n 2 1 ; G roups I I I and IV , e a c h i n 25; G roup V, i n 18; Group V I, i n 2 3 ; and G roup V I I , i n 10. I n s p e c t i o n o f t h e 49 c o m b in a tio n s f a i l s t o r e v e a l any te n d e n c y f o r c e r t a i n o f t h e 7 g r o u p s t o o c c u r t o g e t h e r t o t h e e x c l u s i o n o f o t h e r s . E l u c i d a t i o n o f t h e p a t t e r n and e x t e n t o f t h e s p e c i e s g r o u p s on th e m a in la n d s h e l f was a c h ie v e d b y p l o t t i n g 210 t h e i r o c c u r r e n c e a t t h e s a m p lin g l o c a t i o n s a t w h ich th e y w ere c o l l e c t e d . To im prove t h e c o v e r a g e o f t h i s l a r g e a r e a 66 a d d i t i o n a l c o m p l e t e l y s o r t e d s a m p le s w ere c h e c k e d f o r th e p r e s e n c e o f th e r e c u r r e n t g r o u p s ; t h e s e r e s u l t s w ere i n c lu d e d w i t h t h o s e f o r th e 1 7 6 -sa m p le s e t . G roup I was c o n s i d e r e d p r e s e n t a t a s a m p lin g l o c a t i o n i f a t l e a s t 8 o f i t s 10 s p e c i e s w ere c o l l e c t e d a t t h a t l o c a t i o n . G roup I I was r e c o r d e d i f 5 or m ore o f i t s 6 s p e c i e s were p r e s e n t . G roups I I I to VI w ere r e c o r d e d o n ly i f p r e s e n t a s c o m p le te u n i t s . The d i s t r i b u t i o n o f G roup V II was o m i t t e d fro m t h e map. The g e o g r a p h i c d i s t r i b u t i o n o f th e g r o u p s s u g g e s t s c e r t a i n g e n e r a l i z a t i o n s : ( 1 ) A l l s i x g r o u p s a r e p r e s e n t a lo n g t h e e n t i r e l e n g t h o f th e m a in la n d s h e l f and o c c u r i n a l l e i g h t s h e l f s u b d i v i s i o n s . As p r e v i o u s l y s t a t e d , t y p i c a l l y more t h a n one g ro u p i s c o l l e c t e d i n a s i n g l e s a m p le . (2 ) A te n d e n c y e x i s t s to w a rd a r e d u c t i o n i n th e number o f g r o u p s c o l l e c t e d a t s a m p lin g l o c a t i o n s i n s h a ll o w w a t e r or n e a r s h o r e ; s a m p le s c o n t a i n i n g l e s s th a n 3 o f t h e g ro u p s a re m ost f r e q u e n t l y c o l l e c t e d in t h i s ty p e o f e n v ir o n m e n t. The mean d e p t h o f s a m p le s w i t h l e s s th a n 3 g r o u p s i s 4 5 .8 m e te r s ( r a n g e , 1 0 . 7 - 1 9 9 . 1 m e t e r s ) . S am p les w i t h 3 or more g ro u p s come from s a m p lin g l o c a t i o n s w i t h a mean d e p t h o f 6 8 .0 m e t e r s ( r a n g e , 1 5 . 1 - 1 6 2 . 0 m e t e r s ) . ( 3 ) The g e n e r a l d i s t r i b u t i o n a l p a t t e r n s u g g e s t s th e s e p a r a t i o n o f th e g r o u p s i n t o two r o u g h l y d e f i n e d z o n e s . 211 M u l t i p l e c o m b in a tio n s o f g r o u p s I , I I , I I I , IV and VI p r e d o m in a te on t h e o u t e r p o r t i o n o f t h e s h e l f a lo n g most o f i t s l e n g t h . Sam ples w i t h G ro u p s I I and V or w i t h V a lo n e ( a n d l a c k i n g I , I I I and IV) a r e more common on th e i n n e r p o r t i o n s o f t h e s h e l f . M o st o f t h e sa m p le s l a c k i n g any o f th e g r o u p s a re a l s o c o n f i n e d to t h e s e s h a llo w a r e a s . T h i s g e n e r a l p a t t e r n i s b e s t e x e m p l i f i e d on th e l o n g , n a rro w N ew port-L a J o l l a s h e l f (A re a V I I ) , t h e S a n ta M onica Bay s h e l f (A rea V I ) , and th e n o r t h e r n p a r t o f th e San D iego s h e l f (A rea V i l l a ) . The d i s t r i b u t i o n o f th e g ro u p s ( I - V I ) a t th e sam p l i n g l o c a t i o n s on th e N e w p o rt-L a J o l l a s h e l f i s i l l u s t r a t e d i n F i g u r e 56. V a r i a t i o n s from th e g e n e r a l p a t t e r n o c c u r in some g e o g r a p h ic a r e a s . On th e San P e d ro Bay s h e l f Groups I I and V h av e a b ro a d a r e a l c o v e r a g e . Few s a m p le s w i t h Groups I , I I I , IV and VI w e re c o l l e c t e d fro m t h i s s h e l f seg m en t, and t h e s e w ere c o n c e n t r a t e d a lo n g th e 9 1 -m e te r ( 3 0 0 - f o o t ) c o n t o u r ( F i g u r e 5 7 ) . The d i s t r i b u t i o n o f th e g r o u p s on th e s o u t h e r n p o r t i o n o f th e San D iego s h e l f ( A re a V I I lb ) i s somewhat s i m i l a r t o t h a t o f th e San P ed ro Bay s h e l f . The d i s t r i b u t i o n o f th e g ro u p s on t h e S a n ta B a r b a r a s h e l f i s u n i q u e . I n t h i s a r e a an e a s t - w e s t d i s t r i b u t i o n a l p a t t e r n s u p p l a n t s th e o n s h o r e - o f f s h o r e p a t t e r n o f t h e o t h e r a r e a s . G roups I and IV o c c u r a t m ost sa m p lin g l o c a t i o n s on t h e w e s t e r n p o r t i o n (A re a I l a ) o f th e s h e l f and t h e o u t e r p o r t i o n o f i t s e a s t e r n segm ent (A re a l i b ) . Figure 56 The G e o g ra p h ic D i s t r i b u t i o n o f t h e R e c u r r e n t G roups o f th e M a in la n d S h e l f on t h e N ew p o rt-L a J o l l a S h e l f (L ag u n a t o La J o l l a ) . 212 213 3 0 ' 5 0 ' 4 0 LAGUNA TO LA JOLLA F i g u r e 56 3 0 3 0 ' (I STATVTK MILK * 1.40V WLOm C T C M ) r o o t ( f 1.4 M C T tft) CONTOUft RECURRENT GROUPS SAN C vE ME N TE + *x \ Mi- 20 20 ' •x 3 3 ' 3 3 __I ___ 4 0 ' 5 0 ' 5 0 3 0 ' !I7° 20 Figure 57 The G e o g r a p h ic D i s t r i b u t i o n o f t h e R e c u r r e n t G roups o f th e M a in la n d S h e l f on t h e San P ed ro Bay S h e l f (W h ite s P o i n t to C orona d e l M a r). 214 215 Figure 57 20- 50' WHITES PT. TO CORONA DEL MAR 3 4 ° 34' h=i a l - n i — ST A T U T E M I L E S ( I STATUTE M IU ■ I.S O * KH.OHCTCES > FOOT t t l . 4 METER} CONTOUR R ECU RREN T CROUPS 50' 50' S A N P E D R O 4 0 ' 40' SAM MFOMO f SSA V A I L C Y +•* +»x NEWPORT + • * ! v+. C O R O N A J ) E L M A R + •* ICWMaHT CANVOM 30' 50 2 0 216 For th e most p a r t Group I I i s r e s t r i c t e d t o th e e a s t e r n p o r t i o n o f t h e s h e l f . Sam ples c o n t a i n i n g Group I I , or th e c o m b in a tio n o f G roups I I and V b u t w i t h o u t G roups I , I I I and IV , a s w e l l a s s a m p le s w i t h o u t any g ro u p a t a l l , were c o l l e c t e d fro m th e a r e a a t th e e x tre m e e a s t end o f th e S a n ta B a r b a r a s h e l f ( F i g u r e 5 8 ) . A f a c t o r r e s p o n s i b l e f o r th e r e c u r r e n t g ro u p d i s t r i b u t i o n a l p a t t e r n s i s s u g g e s t e d by th e p a t t e r n s on b o th th e San P ed ro Bay s h e l f ( F ig u r e 57) and t h e S a n ta B a r b a r a s h e l f ( F ig u r e 5 8 ) . B oth p a t t e r n s a p p e a r to r e f l e c t th e s u b s t r a t e c o m p o s itio n o f t h e i r r e s p e c t i v e a r e a s (A p p en d ix F i g u r e s C -7, C -8) . S e d im e n ts a r e r e l a t i v e l y c o a r s e o v er m ost o f th e San P ed ro Bay s h e l f and on t h e e a s t e r n p o r t i o n o f t h e S a n ta B a r b a r a s h e l f . On t h e w e s t e r n h a l f o f th e S a n t a B a r b a r a s h e l f v e r y f i n e s e d im e n ts p r e d o m in a te (m edian d i a m e t e r s , 0 . 0 0 8 - 0 . 0 3 1 mm, F ig u r e 13, W im b e rle y , 1 9 6 4 ). G ro u p s I I and V, a lo n e or t o g e t h e r , p r e d o m in a te i n t h e a r e a s o f c o a r s e r s e d im e n t s . Group I i n c o m b i n a t i o n w ith o t h e r g r o u p s , p a r t i c u l a r l y G roups I I I and IV, o c c u r s i n a r e a s o f f i n e r s e d im e n t . S am ples c o l l e c t e d fro m t h e r e g i o n s o f v e r y f i n e s e d im e n ts o f t h e w e s t e r n h a l f o f th e S a n ta B a r b a r a s h e l f c o n t a i n e d G ro u p s I and IV (so m e tim e s I I I a l s o ) b u t la c k e d I I and V. The s e e m in g ly an o m alo u s sam p le S t a . 5 4 0 4 , (G ro u p s I , I I , I I I , V and VI) a t th e c e n t e r o f A re a I l a ( F i g u r e 58) w as c o l l e c t e d i n a r e g i o n o f c o a r s e r s e d im e n t ( 8 4 . 8 p e r c e n t s a n d ) , t h e C a r p i n t e r i a R ise Figure 58 The G e o g ra p h ic D i s t r i b u t i o n o f t h e R e c u r r e n t G roups o f th e M ain lan d S h e l f on t h e S a n ta B a r b a r a S h e l f ( S a n t a B a r b a r a to M ugu). 217 ST A, BARBARA STA. BARBARA TO MUGU X A R P I N T E Rl A S T A T U T E M I L E ! ( I STA T U T E K IL E • I .E O t K IL O M E T E R S ) ~ nv- s . a- a . 3 0 0 FOO T ( 9 1 .4 M E T E R ) CONTOUR D » 20' 20 •A PT. L A S P I T A S ■ • V E N T U R A +• +• +• V , GROUPS RECURRENT P O R T HUENEME M U iV LASO OA Figure 58 219 D e p o s i t (m e d ia n d i a m e t e r s , 0 . 1 2 5 - 0 . 0 6 2 mm, W im b erle y , 1965, F i g . 1 3 ) . T h a t t h e s e p a t t e r n s o f d i s t r i b u t i o n a r e th e e f f e c t o f s e d im e n t and n o t d e p t h i s s u g g e s t e d by t h e d a t a from 3 s t a t i o n s , S t a . 5 8 2 8 , 5869 and 5870, c o l l e c t e d b e lo w 91 m e te r s on t h e s l o p e o f th e S a n t a B a r b a r a s h e l f . G roups I I and V w ere p r e s e n t i n each o f t h e s e s a m p le s . The s e d im e n t d a t a f o r t h e s e l o c a t i o n s i s p r e s e n t e d i n T a b le 11. For c o m p a ris o n th e means and r a n g e s o f two g r o u p s o f s t a t i o n s h av e b een i n c l u d e d i n t h i s t a b l e : ( 1 ) t e n G roup I I - V S t a t i o n s c o l l e c t e d i n w a te r d e p t h s o f <91 m e t e r s , and (2 ) t h r e e no n -G ro u p I I - V S t a t i o n s c o l l e c t e d i n w a t e r d e p t h s o f >91 m e t e r s . S e d im e n ts a re c o a r s e r a t th e f o u r s a m p lin g l o c a t i o n s i n d e e p w a t e r (>91 m e t e r s ) w here G roup I I and V w ere c o l l e c t e d th a n a t th e t h r e e s t a t i o n s w here t h e y w ere n o t . I n d e e d , v a l u e s f o r m ed ian d i a m e t e r , san d c o n t e n t , s i l t c o n t e n t and c l a y c o n t e n t a t th e Group I I - V s a m p lin g l o c a t i o n s a r e n e a r l y e q u i v a l e n t t o ( S t a . 5828) o r e x c e e d th e mean v a l u e s f o r t h e s e v a r i a b l e s b a s e d on d a t a from th e t e n Group I I - V s a m p lin g l o c a t i o n s i n s h a l l o w e r w a t e r C<91 m e t e r s ) . The d i s t r i b u t i o n o f t h e r e c u r r e n t g r o u p s by a s s o c i a t i o n s i s an i n t e r e s t i n g a s p e c t o f t h i s i n v e s t i g a t i o n . The s e p a r a t i o n o f th e r e c u r r e n t g r o u p s e v i d e n t on t h e b a s i s o f g e o g r a p h i c d i s t r i b u t i o n and e n v i r o n m e n ta l v a r i a b l e s i s p a r t i a l l y r e f l e c t e d i n t h e d i s t r i b u t i o n o f t h e s e g ro u p s by 220 T a b le 11. S ed im e n t D ata f o r G roup I I - V S t a t i o n s fro m th e S a n t a B a r b a r a S h e l f and S lo p e i n W ater D e p th s >91 M e te r s . F or c o m p a r a tiv e p u r p o s e s s e d im e n t d a t a a r e sum m arized (m eans and r a n g e s ) fro m 10 G roup I I - V s t a t i o n s c o l l e c t e d i n <91 m e t e r s and 3 n o n -G ro u p I I - V s t a t i o n s c o l l e c t e d i n >91 m e t e r s . S t a t i o n Number M edian D ia m e te r Sand C o n te n t S i l t C o n te n t C lay C o n te n t 5828 0 .0 5 4 mm 37.46% 5 4 . 86% 5.45% 5869 0 .1 4 2 7 4 .4 6 1 9 .3 4 5.20 5870 0 .0 6 1 4 5 .3 2 5 0 .0 5 4 .6 3 6131 0 .0 8 9 6 4 .5 7 3 1 .2 6 4 .1 7 Means and R a n g e s, 10 G roup I I - V S t a t i o n s , i n <91 M e te rs D epth 0 .0 5 4 0 .0 3 9 - 0 .0 9 2 3 4 .2 1 2 . 86- 97 .2 0 6 1 .8 9 1 .4 0 - 9 3 .5 4 3 .8 9 1 .4 0 - 5 .3 2 Means and R a n g e s, 0 .0 2 7 6 .6 2 8 2 .8 6 1 0 .4 2 3 N on-G roup I I - V S t a t i o n s , i n >91 0 .2 4 - 0 .9 5 - 7 6 .0 2 - 6 .3 4 - M e te rs D epth 0 .3 0 1 6 .6 8 9 1 .4 3 17.90 (D a ta fro m : AHF:USC, 1965, A p p e n d i x - - D a t a , A p p e n d ix T a b le IV) 221 a s s o c i a t i o n s - Each b e n t h i c sam ple was a s s i g n e d an a s s o c i a t i o n d e s i g n a t i o n by t h e AHF s u r v e y b i o l o g i s t (A p p e n d ix T a b le A - 3 ) ; a c c o r d i n g l y , t h e 1 7 6 -sa m p le s e t i s s u b d i v i d e d i n t o a s e r i e s of p r e v i o u s l y d e s c r i b e d s h e l f m a c r o f a u n a l a s s o c i a t i o n s . T h e se sam ple s u b d i v i s i o n s , r e p r e s e n t i n g a s s o c i a t i o n s , were i n v e s t i g a t e d f o r r e c u r r e n t g ro u p d i s t r i b u t i o n . The v a r i a b l e s i n v e s t i g a t e d a s e v i d e n c e s o f g ro u p d i s t r i b u t i o n i n c l u d e t h e f o l l o w i n g : t h e mean number o f g r o u p s p e r sa m p le (maximum, 7) and th e mean number o f s p e c i e s t h a t a r e g ro u p members (maximum, 28 p e r s a m p le ) , and th e mean number o f s p e c i e s o f each g ro u p (maximum, Group I , 10; I I , 6 ; I I I , 4 ; IV -V II, 2 p e r g ro u p ) per s a m p le . The r e s u l t s o f t h i s a n a l y s i s a r e sum m arized i n T a b le 12. The v a l u e s f o r th e A m p h io d ia , A m p h io d ia - C a r d i t a an d A m p h io d ia - O n u p h is a s s o c i a t i o n s a re s i m i l a r . Sam ples c o n s i d e r e d t y p i c a l o f t h e s e t h r e e a s s o c i a t i o n s a v e r a g e d fro m 2 .7 t o 3 .0 r e c u r r e n t g r o u p s p e r sa m p le ; th e mean number o f g r o u p member s p e c i e s a v e r a g e d 2 0 . 4 to 2 0 .6 s p e c i e s p e r s a m p le . The g r o u p s b e s t r e p r e s e n t e d w ere I (mean o f 8.6 t o 9 .8 p e r s a m p le , maximum 1 0 ) , I I (mean o f 4 .2 t o 4 .4 p e r sa m p le , maximum 6) , and I I I (m ean o f 2 . 5 t o 3 .5 p e r s a m p le , maximum 4 ) . G ro u p s IV (m ean o f 1 . 2 t o 1.6 p e r sa m p le , maximum 2) and VI (mean o f 1 .0 t o 1 .3 p e r s a m p le , maximum 2) w ere a l s o p r e s e n t . G roup V and VII s p e c i e s w ere p o o r l y r e p r e s e n t e d . Two r e l a t e d a s s o c i a t i o n s , C h l o e i a - P e c t i n a r i a and Amygdalum p a l l i d u l u m , h a v e s i m i l a r p a t t e r n s . T a b le 12. The R e c u r r e n t Groups o f th e M ain lan d S h e l f , Based on th e A n a l y s i s o f th e 176- Sample S e t , D i s t r i b u t e d by th e B e n th ic A s s o c i a t i o n S u b f i l e s . (4 M e a n N u m b e r o f S p e c i e s < L > 0) X> w X t— i M S ft S ft H M > M H 3 3 3 3 «) H H M H > > > S 0 £ o < u 3 S h -h f t ft ft ft f t ft ft s 0 3 0 0 3 3 3 3 3 3 3 ni 01 O O O O o o O O J ^ cu mh ft U J-4 S h m 5 - 4 5 - 4 o S o w 0 0 0 0 0 0 0 A s s o c i a t i o n A m phiodia 2 .9 20.6 8.6 4 .4 3 .5 1 .4 0 .9 8 1 .3 0 .4 4 (39 s a m p le s ) A m phiodia- C a r d i t a 2 .7 2 0 .4 8.8 4 .2 3 .1 1.6 0 .5 6 1 .3 0 .5 9 (22 sa m p les) A m phiodia- O nuphis 3 .0 2 0 .7 9 .8 4 .5 2 .5 1.2 1.0 1.0 0 .5 0 ( 4 sa m p le s) C h l o e i a - P e c t i n a r i a 1.8 1 9.7 9 .0 5 .0 2 .3 1 .3 0 .8 0 1 .3 0 .3 0 ( 4 sa m p le s) Amygdalum p a l l i d u l u m 2.8 20.2 8.0 5 .8 3 .3 0 .5 1.0 2.0 0.00 ( 4 s a m p le s) O n u p h is; . O n u p h is -P h e ru s a 1.8 1 6 .3 7 .2 5 .0 2.2 0 .7 5 1 .3 0 .5 0 0.00 ( 4 s a m p le s) A m phioplus h e x a c a n th u s 2.0 15.6 6 .5 4 .8 0 .7 5 0 .7 5 1.8 0 .7 5 0 .3 8 ( 8 s a m p le s ) co w co Table 12 (Cont.) Mean Number o f S p e c ie s Mean Number of G roups Mean Number of Group S p e c ie s Group I Group I I Group I I I Group IV Group V Group VI Group V II A s s o c i a t i o n (Cont .) L i s t r i o l o b u s p e lo d e s 2.0 1 5.7 7 .5 2 .5 1 . 6 1 .9 0 .4 4 0 .4 4 0 .7 8 C 9 s a m p le s) N o t h r i a - T e l l i n a 0 .9 4 1 1 .4 4 .3 4 .2 0 .1 5 0 .7 0 1.1 0.21 0 .3 9 (33 sa m p le s) D i o p a t r a 0 .7 2 1 0 .4 2.8 4 .4 0 .5 5 0 .2 7 1.0 0.10 0 .2 7 (11 sa m p le s) N o t h r i a - S p io p h a n e s 0 .4 3 5 .3 0.86 2 .7 0.0 0 .1 4 1 .3 0.0 0 .4 3 ( 7 sa m p le s) Maximum V alu es 7* 28** 10*** 4 - k i c k 2 ‘ > v v o V Number o f G roups = * Number o f Group S p e c ie s = ** Number o f S p e c ie s /G ro u p = *** w co O J 224 Sam ples from t h e A m p h io p lu s h e x a c a n t h u s a s s o c i a t i o n , d e s c r i b e d by B a r n a r d and Z ie s e n h e n n e (1 9 6 1 ) a s s i m i l a r to t h e A m phiodia u r t i c a a s s o c i a t i o n b u t d i s t i n c t fro m i t , have a somewhat d i f f e r e n t p a t t e r n o f r e c u r r e n t g ro u p d i s t r i b u t i o n . E i g h t s a m p le s c o n s i d e r e d t o be c o l l e c t e d fro m t h i s a s s o c i a t i o n a v e r a g e d 2 r e c u r r e n t g ro u p s p e r sam ple and 1 5 .6 s p e c i e s g ro u p members p e r s a m p le . The g r o u p s b e s t r e p r e s e n t e d w ere I (mean = 6 . 5 s p e c i e s p e r s a m p le ) , I I (mean = 4 . 8 s p e c i e s p e r s a m p le ) , and V (mean = 1 . 8 s p e c i e s p e r sam p l e , maximum 2 ) . G roups I I I and IV a r e r e l a t i v e l y u n im p o r t a n t i n t h i s a s s o c i a t i o n . The d i s t i n c t i v e L i s t r i o l o b u s a s s o c i a t i o n d e v i a t e s i n a somewhat s i m i l a r m an n er. Sam ples a v e r a g e 2 g r o u p s and 1 5 .7 g ro u p member s p e c i e s ; n o te w o r th y g ro u p s a r e I (mean = 7 . 5 s p e c i e s p e r s a m p le ) and IV (mean = 1 .9 s p e c i e s p e r sam p l e ) . Two s h a l l o w - w a t e r a s s o c i a t i o n s , N o t h r i a - T e l l i n a and D i o p a t r a , have v e r y s i m i l a r p a t t e r n s o f r e c u r r e n t g ro u p d i s t r i b u t i o n ; b o t h d e v i a t e m a rk e d ly fro m th e A m p h io d ia a s s o c i a t i o n p a t t e r n . The mean num ber o f g r o u p s p e r sa m p le i n t h e s e two a s s o c i a t i o n s i s l e s s th a n 1 ; th e mean number o f g ro u p member s p e c i e s i s s l i g h t l y o ver 10. G roups I I (mean = 4 . 2 t o 4 .4 p e r sa m p le ) and V (mean = 1 .0 t o 1 .1 p e r sam p l e ) a r e th e i m p o r t a n t r e c u r r e n t g r o u p s . F u r t h e r c o m p a riso n o f th e d i s t r i b u t i o n o f r e c u r r e n t g ro u p s b y a s s o c i a t i o n s i s made i n F i g u r e s 59 and 6 0 . Figure 59 A G raph o f t h e Number o f S p e c i e s o f M a in la n d S h e l f R e c u r r e n t G roups I I and V A g a i n s t th e Number o f S p e c i e s o f G roups I , I I I , IV and VI f o r t h e A m phiodia and A m p h io d ia - C a r d i t a A s s o c i a t i o n s . 225 226 Figure 59 • AMPHIODIA O AMPHIODIA-CARDITA X MEANS W CD Q. 3 O oc o CD UJ o 1 1 1 Q. CD u. o Q C 1 1 1 m 8 - • • •• •• 7~ • o • • O •• mo 00 0P 6 - • • • mo oo ••co p 5- • o X ® p 4- • OOP OP OP • 3- • 00* OP O 2- • cm O • 1 - o • ii A i b A 1 2 l b 1 1 4 1 1 5 i k 1 1 1 7 1 8 NUMBER OF SPECIES GROUPS MH-32-3Z1 Figure 60 A Graph o f th e Number of S p e c ie s o f M a in la n d S h e l f R e c u r r e n t G ro u p s I I an d V A g a i n s t the Number o f S p e c i e s o f Groups I , I I I , IV and VI f o r the N o t h r i a - T e l l i n a and D i o p a t r a A s s o c i a t i o n s . 227 GROUPS E - l NUMBER O F SPECIES o NOTHRIA-TELLINA AND DIOPATRA 7 MEANS 0 1 o oo o o o o y-J O O O O O 00 O 00 6- o oo o o o o oo _ v *n I-1 * 5H o 00 X O O C 4 (C o o o o 3 - 8 o oo o ooo o o oo o o 2 - o o I - i i i i i i i i i i i i i r I 2 3 4 5 6 7 8 9 10 I I 12 13 14 NUMBER OF SPECIES g r o u ps i-m. -w. -m o o M IN J CO F i g u r e 59 i s a p l o t o f t h e number o f s p e c i e s o f G roups I , I I I , IV, and VI (num bered a lo n g th e a b s c i s s a ) a g a i n s t th e number o f s p e c i e s o f G roups I I and V (n u m b e red a lo n g th e o r d i n a t e ) f o r th e 61 s a m p le s c o l l e c t e d fro m th e A m phiodia ( s o l i d d o t s ) and A m p h io d ia - C a r d i t a (o p e n c i r c l e s ) a s s o c i a t i o n s . An X sym bol m ark s th e p o s i t i o n o f th e mean o f a l l t h e s e p o i n t s . The p o i n t s a r e c l u s t e r e d b e tw e e n 9 and 18 w i t h a mean o f 1 4 .8 (G ro u p s I - I I I - I V - V I ) and b e tw e e n 1 and 8 w i t h a mean o f 5 .2 (G ro u p s I I - V ) . From t h i s s c a t t e r g r a p h i t a p p e a r s t h a t a s l i g h t p o s i t i v e c o r r e l a t i o n e x i s t s b e tw e e n th e number o f s p e c i e s o f th e two c o m b i n a t i o n s o f g r o u p s i n t h e s a m p le s c o l l e c t e d fro m t h e s e two a s s o c i a t i o n s . The P e a r s o n p ro d u c t-m o m e n t c o r r e l a t i o n c o e f f i c i e n t f o r t h i s d i s t r i b u t i o n i s a low 0 .2 1 3 . S in c e t h i s v a lu e o f £ f o r 59 d . f . (N - 2) i s belo w t h e 0 .0 5 l e v e l o f s i g n i f i c a n c e ( r = 0 . 2 5 2 ) , t h e c o r r e l a t i o n may be th e r e s u l t o f ch an ce f a c t o r s i n s a m p lin g . F i g u r e 60 i s b a s e d on th e d a t a fro m th e 58 sa m p le s c o l l e c t e d fro m th e N o t h r i a - T e l l i n a and P i o p a .tra a s s o c i a - _ tio n s -C fe o th m arked by open c i r c l e s ) . The p o i n t s a r e c l u s t e r e d b e tw e e n 0 and 14 w i t h a mean o f 4 .9 ( I - I I I - I V - V I ) and b e tw e e n 2 and 8 w ith a mean o f 4 . 9 ( I I - V ) . No r e l a t i o n s h i p b e tw e e n th e number o f s p e c i e s o f th e two c o m b i n a t i o n s of g ro u p s i n t h e s a m p le s fro m t h e s e two a s s o c i a t i o n s i s r e a d i l y a p p a r e n t . The P e a r s o n p ro d u c t-m o m e n t c o r r e l a t i o n c o e f f i c i e n t o f t h i s d i s t r i b u t i o n i s - 0 . 202 , i n d i c a t i n g a low 230 n e g a t i v e c o r r e l a t i o n . H ow ever, t h i s v a l u e i s b elo w t h e 0 .0 5 l e v e l o f s i g n i f i c a n c e ( r = 0 .2 5 9 , 56 d . f . ) . I f th e r e l a t i o n s h i p s d e m o n s tr a te d by t h e s e two f i g u r e s s h o u ld b e v a l i d ( i n s p i t e o f t h e low x_ v a l u e s ) , t h e n i t i s a p p a r e n t t h a t th e number o f s p e c i e s o f G ro u p s I - I I I - I V - V I and th e number o f s p e c i e s o f G roups I I- V i n s a m p le s c o l l e c t e d fro m th e A m p h io d ia and A m p h io d ia - C a r d i t a a s s o c i a t i o n s have a r e l a t i o n s h i p o p p o s i t e t o t h a t i n s a m p le s c o l l e c t e d fro m th e N o t h r i a - T e l l i n a and D i o p a t r a a s s o c i a t i o n s . The N o r t h e r n S h e l f R e c u r r e n t Groupsi The m a in la n d s h e l f i s a h e t e r o g e n e o u s r e g i o n ; i t s s u b s t r a t e s a r e h i g h l y v a r i a b l e and i t s m a c r o fa u n a d i v e r s e . C o n s e q u e n tly an a n a l y t i c a l p r o c e d u r e su ch a s t h e r e c u r r e n t g ro u p a n a l y s i s may f a i l t o a c h i e v e i t s maximum l e v e l o f e f f e c t i v e n e s s when a p p l i e d t o a m o d e r a t e l y s i z e d sam ple s e t drawn fro m s u c h a com plex u n i t . I n an e f f o r t to n a r ro w th e f o c u s o f t h i s m ethod to a s m a l l e r and l e s s com plex r e g i o n , a s e p a r a t e a n a l y s i s was made o f t h e 74 s a m p le s c o l l e c t e d in A re a s I , I I and I I I ( t h e n o r t h e r n s h e l f ) . I t was a n t i c i p a t e d t h a t th e r e s u l t s o f su ch an a n a l y s i s would y i e l d r e c u r r e n t g ro u p s t h a t w ould a p p ro x im a te t h e c l a s s i c a l l y d e f i n e d c o m m u n itie s o f t h i s r e g i o n . The t o p 200 s p e c i e s ( a s ra n k e d by f r e q u e n c y i n th e 1 7 6 -sa m p le s e t ) w ere a n a l y z e d b y t h e r e c u r r e n t g ro u p m ethod. F i f t y - n i n e s p e c i e s showed a f f i n i t y w ith o t h e r s p e c i e s when th e a f f i n i t y i n d e x was s e t a t 0 . 6 5 0 ; t h e s e 59 i n c l u d e 21 p o l y c h a e t e s , 24 c r u s t a c e a n s , 2 e c h in o d e r m s , 8 m o llu s k s and 4 f ro m o th e r t a x a . T h i r t y - n i n e o f t h e s e s p e c i e s c o u ld be a r r a n g e d i n 12 g ro u p s ; t h e r e m a in in g 21 s p e c i e s had a f f i n i t i e s w ith som e, b u t n o t a l l , o f t h e members o f one o r more o f t h e s e g r o u p s . T a b le 13 p r e s e n t s th e 12 r e c u r r e n t g ro u p s l i s t i n g ( 1) t h e s p e c i e s c o n s t i t u t i n g e a c h g ro u p , ( 2 ) th e s p e c i e s show ing a f f i n i t y to p a r t i c u l a r g r o u p s , (3 ) th e g ro u p a f f i l i a t i o n o f t h e s p e c i e s , i f a n y , i n th e r e c u r r e n t g r o u p s r e s u l t i n g from t h e a n a l y s i s o f t h e e n t i r e sam ple s e t ( T a b le 1 0 ), ( 4 ) th e num ber o f t h e o c c u r r e n c e s o f e a c h s p e c i e s i n th e 7 4 -s a m p le s u b s e t , ( 5 ) th e number o f a f f i n i t i e s th e s p e c i e s h a s w ith o t h e r s p e c i e s , and ( 6 ) t h e s p e c i e s common to T a b le 10 as i n d i c a t e d by an a s t e r i s k . The i n t e r g ro u p r e l a t i o n s h i p s o f 7 o f th e 12 g r o u p s a r e shown d i a - g r a m a t i c a l l y i n F ig u r e 61; th e 5 g ro u p s n o t i n c l u d e d i n t h i s d ia g r a m l a c k any i n t e r - g r o u p c o n n e c t i o n s . O nly 10 o u t o f t h e 66 maximum p o s s i b l e c o n n e c t i o n s f o r 12 g r o u p s o c c u r . The d e g r e e t o w h ic h a n y two g r o u p s a r e l i n k e d i s i n d i c a t e d by a f r a c t i o n p la c e d b e s i d e t h e l i n e draw n b e tw e e n th e 2 g r o u p s . T h e se f r a c t i o n s a r e t h e r a t i o s o f th e o b s e rv e d i n t e r - g r o u p a f f i n i t i e s ( s p e c i e s - p a i r s w i t h a f f i n i t i e s ) t o t h e maximum p o s s i b l e i n t e r - g r o u p a f f i n i t i e s . The f i r s t g r o u p , Group N - I , d e r i v e d by t h e a n a l y s i s o f t h e n o r t h e r n s h e l f sam p le s u b s e t i s an a sse m b la g e o f 13 s p e c i e s --8 p o l y c h a e t e s , 3 c r u s t a c e a n s ( 2 is o p o d s and 1 T a b le 1 3 . The R e c u r r e n t Groups o f th e N o r t h e r n S h e l f B ased on t h e A n a l y s i s of t h e 74 S am ples o f th e 176- Sam ple S e t fro m t h i s R e g io n , I . A . = 0 .6 5 0 . R e c u r r e n t G roups O c c u r re n c e A f f i n i t i e s GROUP N - I : ^A m phiodia u r t i c a , I 71 29 * P e c t i n a r i a c a l i f o r n i e n s i s , I 63 26 * P h o lo e g l a b r a , I 56 26 * P r i o n o s p i o p i n n a t a , I 69 26 * H e te ro p h o x u s o c u l a t u s , I I I 51 23 * G ly c e r a c a p i t a t a , I 47 22 * A x in o p s id a s e r r i c a t a , I 46 21 G n a t h i a c r e n u l a t i f r o n s , I 46 20 * A m p e lisc a b r e v i s i m u l a t a , I 52 18 T e r e b e l l i d e s s t r o e m i , I 54 17 H a lio p h a s m a g e m in a ta , A - I , I I , I I I 47 17 * C o s s u r a c a n d i d a , IV 49 15 * S t e r n a s p i s f o s s o r , IV 47 13 A s s o c i a t e d w i t h Group N - I : E u d o r e l l a A, A - I I I 33 3 P a ra p h o x u s r o b u s t u s , A -I 31 1 A x i o t h e l l a r u b r o c i n c t a , A -I 40 1 T e le p s a v u s c o s ta ru m 38 1 P i n n i x a s p . 38 3 Compsomyax s u b d ia p h a n a 37 2 N e p h ty s f e r r u g i n e a , A - I , I I I 41 12 233 Table 13 (Cont.) A s s o c i a t e d w i t h G roup N -I ( C o n t . ) : L a o n ic e c i r r a t a , A - I , I I 42 7 B y b l i s v e l e r o n i s 30 4 C a r d i t a v e n t r i c o s a 33 3 G o n ia d a b r u n n e a , A - I , I I 45 6 * S p io p h a n e s m i s s i o n e n s i s 43 6 nem atode unknown, V 40 4 GROUP N - I I : * n e m e rte a n unknown, I I 63 20 * P r i o n o s p i o m a lm g r e n i, I I 55 14 ■ ^ostracods unknown, I I 49 15 * t a n a i d s unknown, I I 47 17 ^ P a r o n i s g r a c i l i s , I 53 18 A s s o c i a t e d w i t h GROUP N - I I : P i n n i x a s p . 38 3 Compsomyax s u b d ia p h a n a 37 2 N e p h ty s f e r r u g i n e a , A - I , I I I 41 12 L a o n ic e c i r r a t a , A - I , I I 42 7 G o n ia d a b r u n n e a , A - I , I I 45 6 * S p io p h a n e s m i s s i o n e n s i s , A - I , I I 43 6 * nem ato d e unknown, V 40 4 GROUP N - I I I : A m p e lis c a p a c i f i c a , I I I 38 19 234 Table 13 (Cont.) R e c u r r e n t G roups O c c u r re n c e A f f i n i t i e s GROUP N - I I I ( C o n t . ) : Nem ocardium c e n t i f i l o s u m , A - I I I 29 5 * P a ra p h o x u s s i m i l i s , I I I 34 10 A s s o c i a t e d w i t h GROUP N - I I I : * P a ra p h o x u s b i c u s p i d a t u s , I I I 30 1 s i p u n c u l i d unknown 31 1 B y b lis v e l e r o n i s 30 4 A d o n t o r h in a c y c l i a 26 2 C a r d i t a v e n t r i c o s a 33 3 N u c u la t e n u i s 27 1 M aldane s a r s i 28 1 GROUP N-IV : * A m p h ip h o lis s q u a m a ta , I I 55 12 * T h a ry x t e s s e l a t a , I I 48 9 A s s o c i a t e d w i t h GROUP IV: G o n iad a b r u n n e a , A - I , I I 45 6 * S p io p h a n e s m i s s i o n e n s i s , A - I , I I 43 6 ■^nematode unknown, V 40 4 GROUP N-V: * A m p e lisc a c r i s t a t a , A - I , A m p e lis c a c o m p re ssa I I 38 33 4 1 235 Table 13 (Cont.) R e c u r r e n t G roups O c c u r re n c e A f f i n i t i e s GROUP N -V I: D i a s t y l i d a e unknown, VI 36 8 A m p e lis c a p u g e t i c a , VI 33 5 A s s o c i a t e d w i t h GROUP V I: C h l o e i a p i n n a t a , A -I 27 1 GROUP N - V I I : N u c u la n a t a p h r i a 35 1 e n t e r o p n e u s t unknown 26 1 GROUP N - V I I I : T e l l i n a b u t t o n i 25 2 C h a e to z o n e c o ro n a 22 1 GROUP N -IX : P a ra p h o x u s e p ito m u s 24 1 P a ra p h o x u s s t e n o d e s 21 1 GROUP N-X: brow n o s t r a c o d , V II 23 2 r e c t a n g u l a r o s t r a c o d , V II 19 1 A s s o c i a t e d w ith GROUP N-X: o v a l o s t r a c o d 16 1 GROUP N -X I: T h a l e n e s s a s p i n o s a 22 1 236 Table 13 (Cont.) R e c u r r e n t G roups O c c u r re n c e A f f i n i t i e s GROUP N-XI ( C o n t . ) : N ep h ty x c a e c o i d e s 14 1 GROUP N -X II: P a ra p h o x u s f a t i g a n s P a r a p h o x u s v a r i a t u s * = common t o T a b le 4 Roman n u m e r a ls i n d i c a t e t h e r e c u r r e n t g ro u p a f f i l i a t i o n s and a s s o c i a t i o n s o f s p e c i e s i n th e a n a l y s i s o f th e e n t i r e 1 7 6 -sa m p le s e t . 16 13 1 1 Figure 61 A D ia g ra m m a tic R e p r e s e n t a t i o n o f t h e I n t e r - r e l a t i o n s h i p o f the R e c u r r e n t G roups o f t h e N o r t h e r n S h e l f Based on I n t e r - Group A f f i n i t i e s . The f r a c t i o n s a r e th e r a t i o s o f th e ob s e r v e d i n t e r - g r o u p a f f i n i t i e s t o t h e maximum p o s s i b l e i n t e r - g r o u p a f f i n i t i e s . I n t h i s f i g u r e t h e l i n e s a r e n o t p r o p o r t i o n a l t o th e i n v e r s e o f t h e s e v a l u e s as t h e f i g u r e c o u ld n o t be s o c o n s t r u c t e d w i t h o u t th e u s e o f c u r v e d l i n e s . 237 u - m 1/15 9/26 / ^ N / 1 8 / 3 9 N“I ) 44/65 ( N' n 2/10 8 /26 2/10 238 239 a m p h ip o d ) , 1 o p h i u r o i d and 1 p e l e c y p o d . G roup N - l i s s i m i l a r t o G roup I d e r i v e d fro m t h e e n t i r e 1 7 6 -sa m p le s e t , and c o n t a i n s a l l o f i t s e l e m e n t s e x c e p t th e p o l y c h a e t e P a r a o n i s g r a c i l i s ; th e o t h e r 4 s p e c i e s o f Group N -I a r e th e amphipod H e te r o p h o x u s o c c u l a t u s (G roup I I I ) , th e i s o p o d H a lio p h a sm a g e m in a ta t h a t i n th e f i r s t a n a l y s i s had a f f i n i t y w i t h G roups I , I I and I I I , and t h e p o l y c h a e t e s C o s s u r a C an d id a and S t e r n a s p i s f o s s o r t h a t c o n s t i t u t e d G roup IV. T h i s com b i n a t i o n o f e l e m e n t s o f G roups I , I I I and IV to fo rm a s i n g l e g r o u p , G roup N - I , i s c o n s i s t e n t w i t h t h e i r te n d e n c y to a s s o c i a t e on t h e b a s i s o f e n v i r o n m e n ta l v a r i a b l e s as p r e v i o u s l y i n d i c a t e d . T h i r t e e n s p e c i e s a r e a s s o c i a t e d by one or more a f f i n i t i e s w i t h Group N - I . P o u r of t h e s e , 2 c r u s t a c e a n s ( t h e am phipod P a ra p h o x u s r o b u s t u s and t h e cum acean E u d o r e l l a A) and 2 p o l y c h a e t e s (A x i o t h e l l a r u b r o c i n c t a and T e l e p s a v u s c o s ta r u m ) , have a f f i n i t i e s w ith t h i s g ro u p a l o n e . Of t h e r e m a i n in g n in e s p e c i e s 4 a r e a l s o a s s o c i a t e d w i t h G roup N - I I , two s p e c i e s ( i n c l u d i n g t h e p e le c y p o d C a r d i t a v e n t r i c o s a ) a r e a s s o c i a t e d w ith G roup I I I and 3 a r e a s s o c i a t e d w i t h G roups I I and IV. Group N -I h a s i n t e r - g r o u p c o n n e c t i o n s w i t h o n ly 4 o t h e r g r o u p s , G roups N - I I , N - I I I , N-IV and N-VI ( F i g u r e 6 1 ) . I t i s m ost i n t i m a t e l y bound to Group N - I I ; 44 o f th e p o s s i b l e 65 s p e c i e s - p a i r a f f i n i t i e s (68 p e r c e n t) o c c u r b e tw een t h e s e two g r o u p s . G roup N -I i s l e s s c l o s e l y l i n k e d t o N - I I I w i t h 18 o f 39 (5 4 p e r c e n t ) p o s s i b l e s p e c i e s - p a i r s 240 showing a f f i n i t i e s . G roup N -I s h a r e s a lm o s t th e same num b e r o f a f f i n i t i e s w i t h G roups N-IV (9 o f 26 or 35 p er c e n t ) and N-VI (8 o f 26 or 31 p e r c e n t ) . F ive f a u n a l e le m e n ts co m p rise Group N - I I — 2 p o l y c h a e t e s , 2 c r u s t a c e a n s Ca t a n a i d and an o s t r a c o d ) and 1 n e m e rte a n (T a b le 1 3 ); 3 o f t h e s e , th e two c r u s t a c e a n s and th e n e m e r te a n , c o u ld n o t be i d e n t i f i e d t o s p e c i e s . Four o f th e f i v e s p e c i e s c o n s t i t u t i n g t h i s g ro u p a r e a l s o members o f t h e g ro u p form ed a t th e se c o n d l e v e l i n th e a n a l y s i s o f th e 1 7 6 -sam p le s e t . T h is a sse m b la g e d i f f e r s by t h e a d d i t i o n o f th e p o l y c h a e t e P a r a o n i s g r a c i l i s (G roup I , e n t i r e 17 6 -sam p le a n a l y s i s ) and th e e l i m i n a t i o n o f t h e o p h i u r o i d A m p h ip h o lis sq u a m a ta and th e p o l y c h a e t e T h a ry x t e s s e l a t a . Seven s p e c i e s , 4 p o l y c h a e t e s , 1 c r u s t a c e a n (a d e c a p o d ) , 1 m o llu sk ( a p e le c y p o d ) and a n em a to d e , have a f f i n i t i e s o n ly w ith t h i s g ro u p ( T a b le 1 3 ) . Group N - I I h a s i n t e r - g r o u p c o n n e c tio n s w ith 4 o t h e r g ro u p s b e s i d e s Group N - I ; o f th e p o s s i b l e 10 c o n n e c tio n s b etw een Group N - I I and Group N-IV s i x (60 p e r c e n t ) o c c u r ; 2 o f 10 p o s s i b l e c o n n e c t i o n s (20 p er c e n t ) betw een b o t h Group N - I I and Group N-V and Group N-VI a r e p r e s e n t . The li n k a g e b e tw e e n Group N - I I and N - I I I i s weak ( o n ly 1 of 15 o r 7 p e r c e n t o f t h e p o s s i b l e a f f i n i t i e s ) . The t h r e e s p e c i e s t h a t c o m p rise Group N - I I I , 2 amphipod c r u s t a c e a n s and 1 p e le c y p o d m o llu s k , a r e members of t h e group form ed a t th e t h i r d l e v e l ( t h e 2 am phipods) i n 241 t h e a n a l y s i s o f th e e n t i r e s a m p le s e t or a r e among th e s p e c i e s h a v in g a f f i n i t y o n l y w i t h t h i s g ro u p ( t h e p e l e c y p o d ) . S e v e n s p e c i e s , 1 p o l y c h a e t e , 2 a m p h ip o d s, 3 p e l e c y p o d s ( i n c l u d i n g th e a s s o c i a t i o n " d o m in a n t” C a r d i t a v e n t r i c o s a ) and a s i p u n c u l i d , a r e a s s o c i a t e d w i t h G roup N - I I I . B e s i d e s i t s i n t e r - g r o u p c o n n e c t i o n s w i t h G ro u p s N -I and N - I I , Group N - I I I i s l i n k e d t o G ro u p N-IV; one o f s i x p o t e n t i a l i n t e r g ro u p a f f i n i t i e s i s p r e s e n t . G roup N-IV c o n s i s t s o f two s p e c i e s , t h e o p h i u r o i d A m p h ip h o lis sq u a m a ta and t h e p o l y c h a e t e T h a ry x t e s s e l a t a , t h a t w ere b o t h members o f Group I I d e r i v e d from t h e a n a l y s i s o f t h e e n t i r e s e t o f 176 s a m p le s . The f o u r s p e c i e s a s s o c i a t e d w i t h t h i s g ro u p (2 p o l y c h a e t e s , 1 m o llu s k and 1 n e m a to d e ) i n c l u d e 2 s p e c i e s t h a t w ere a s s o c i a t e d w i t h G roup I I and 1 member o f G roup V. G roup N -IV i s r e l a t e d by i t s c o m p o s itio n t o b o th G roup N - I I and G roup I I . The t h r e e i n t e r - g r o u p c o n n e c t i o n s ( t o G ro u p s N - I , I I and I I I ) o f G roup N-IV h a v e been d i s c u s s e d p r e v i o u s l y . G roup N-V i s com posed o f 2 amphipod c r u s t a c e a n s . No s p e c i e s a r e a s s o c i a t e d w i t h t h i s g r o u p . I t i s l i n k e d t o G roup N - I I ( 2 o f 10 p o s s i b l e i n t e r - g r o u p a f f i n i t i e s p r e s e n t ) and G roup N -V III (1 o f 4 p o s s i b l e a f f i n i t i e s ) . Group N-VI i s i d e n t i c a l t o G roup VI d e v e lo p e d a s a r e s u l t o f t h e a n a l y s i s o f t h e e n t i r e sam p le s e t . The p o l y c h a e t e C h l o e i a p i n n a t a ( a s s o c i a t e d i n th e p r e v i o u s a n a l y s i s w i t h Group I ) i s a s s o c i a t e d w i t h Group N-VI. The 242 i n t e r - g r o u p c o n n e c t i o n s o f t h i s G ro u p w ith G roups N -I and N - I I have been d i s c u s s e d . Group N - V II I i n c l u d e s t h e p e le c y p o d T e l l i n a b u t t o n i , a " c o - d o m in a n t” w ith N o t h r i a e l e g a n s in t h e N o t h r i a - T e l l i n a a s s o c i a t i o n , a n d t h e p o l y c h a e t e C h a e to z o n e c o r o n a . T h e re a r e no a s s o c i a t e d s p e c i e s . I t i s c o n n e c te d o n ly t o Group N-V; one of t h e 4 p o s s i b l e s p e c i e s - p a i r a f f i n i t i e s p o s s i b l e b e tw e e n th e s e tw o g ro u p s i s p r e s e n t . Group N -V III o c c u p i e s a r a t h e r i s o l a t e d p o s i t i o n i n r e l a t i o n s h i p t o t h e o t h e r g r o u p s (N -I, I I , I I I , IV and VI) i n t h i s s y s t e m . Five g r o u p s w ere form ed i n t h i s a n a l y s i s t h a t la c k i n t e r - g r o u p c o n n e c t i o n s . Each i s composed o f b u t 2 s p e c i e s . Only o n e , Group N-X, has an a s s o c i a t e d s p e c i e s ; t h i s g r o u p i s the o n l y one t h a t b e a r s a n y r e s e m b la n c e t o th e g r o u p s form ed i n th e a n a l y s i s o f t h e e n t i r e sam ple s e t ; i t h a s one member i n common w i t h G ro u p V I I. The d i s t r i b u t i o n o f th e r e c u r r e n t g r o u p s o f th e 74 s a m p le s from t h e n o r t h e r n p o r t i o n o f th e m a in la n d s h e l f ( A r e a s I , I I an d I I I ) was exam ined o n ly on t h e S a n t a - - B a r b a r a s h e l f ( A r e a I I ) . Here t h e d i s t r i b u t i o n p a t t e r n o f th e c l a s s i c a l a s s o c i a t i o n s i s f a i r l y sim p le ( B a r n a r d and H a rtm a n , 1959; J o n e s , 1 9 6 4 ) . O n ly th e g r o u p s w ith i n t e r g ro u p c o n n e c t i o n s (G ro u p s N-I t h r o u g h VI and V I I I ) w e re m apped. In o r d e r to im p ro v e th e c o v e ra g e o f t h i s r e g i o n i n f o r m a t i o n f ro m 24 c o m p l e t e l y s o r t e d s a m p le s was u s e d to s u p p le m e n t t h e d a t a o f t h e 41 A re a I I s a m p le s t h a t a r e p a r t 243 o f t h e n o r t h e r n s h e l f s u b s e t . G roup N -I was c o n s i d e r e d p r e s e n t i f 11 o r more o f i t s 13 s p e c i e s members w ere p r e s e n t i n a s a m p le . Group N - I I was r e c o r d e d i f a t l e a s t 4 o f i t s 5 s p e c i e s w ere p r e s e n t . G ro u p s N - I I I - N-VI and N -V III had t o be p r e s e n t a s c o m p le te u n i t s . I n a d d i t i o n to t h i s i n f o r m a t i o n t h e t h r e e m a jo r b e n t h i c a s s o c i a t i o n s o f t h i s r e g i o n , th e A m p h io d ia - C a r d i t a a s s o c i a t i o n , th e L i s t r i o l o b u s a s s o c i a t i o n and th e N o t h r i a - T e l l i n a a s s o c i a t i o n , a r e mapped b a s e d on th e a s s o c i a t i o n d e s i g n a t i o n s a s s i g n e d to t h e s e 65 s a m p le s (A p p e n d ix T a b le A - 3 ) . T h is map ( F i g u r e 62) p r o v i d e s d i r e c t c o m p a ris o n o f th e d i s t r i b u t i o n s o f th e r e c u r r e n t g r o u p s and t h e s e b e n t h i c a s s o c i a t i o n s . U h i l e a o n e - t o - o n e g ro u p t o a s s o c i a t i o n r e l a t i o n s h i p d o e s n o t e x i s t , t h e g ro u p o f s a m p le s c o l l e c t e d from one o f t h e s e b e n t h i c a s s o c i a t i o n s c o n t a i n s a c h a r a c t e r i s t i c p a t t e r n o f r e c u r r e n t g r o u p s . S am ples fro m t h e A m p h io d ia - C a r d i t a a s s o c i a t i o n c o n t a i n e d a l l o f t h e g r o u p s (N -I t h r o u g h N-VI) e x c e p t G roup N - V I I I . G roup N-V was p o o r l y r e p r e s e n t e d b e i n g p r e s e n t i n a p p r o x i m a t e l y 30 p e r c e n t o f t h e s a m p le s ; G roups N - I , I I , I I I , IV and VI w e re w e l l r e p r e s e n t e d (50 t o 75 p e r c e n t ) . The mean number o f g ro u p s p e r sam ple i s 3 . 4 . L i s t r i o l o b u s com m unity s a m p le s la c k e d G ro u p s N - I I I an d N - V I I I ; G roups N-IV and N-V w ere e a c h r e p r e s e n t e d o n l y in one sam ple (8 p e r c e n t ) ; G roup VI was p o o r l y r e p r e s e n t e d , o c c u r r i n g i n o n ly 3 o f 12 s a m p le s (25 p e r c e n t ) . O n ly Group I (7 o f 12 s a m p le s or 58 p e r c e n t ) Figure 62 The G e o g ra p h ic D i s t r i b u t i o n o f t h e R e c u r r e n t G roups o f t h e N o r t h e r n S h e l f on t h e S a n ta B a r b a r a S h e l f ( S a n t a B a r b a r a to M ugu). 244 20' 10' N T E R 10' BARBARA TO MUGU i" r-Baa i — i STATUTE MILES ( I STATUTE MILE • ISOS KILOMETERS) 3 0 0 FOOT (9 1 .4 METERJCONTOUR 34e RECURRENT N - I N -H N -m * N -rz • N - 2 . N - 2 I ■ N-M ■ AMPHIODIA- LISTRIOLOB'JS NOTHRIA - T su \ / o V i r I* - V r x J * \ 4+0 \ + Q \ A □ \ ! _____ ! + \ V GROUPS A □ T + X A CAROITA V . V E N T U R A PO R T HUENEME ELLIN A 20' **UGU LAGOOK N § ^ 10 ' 3 4 4 0 ' 3 0 ' 20' 10' co in Figure 62 246 and G roup I I (5 o f 12 s a m p le s or 42 p e r c e n t ) a r e a t a l l w e l l r e p r e s e n t e d . Four o f t h e s a m p le s (33 p e r c e n t ) l a c k a l l g r o u p s . The mean number o f g r o u p s p e r sam p le i n t h i s a s s o c i a t i o n i s o n l y 1 . 3 , p o i n t i n g u p t h e g e n e r a l t r e n d i n t h e L i s t r i o l o b u s sa m p le s to w a rd a r e d u c t i o n i n th e num ber o f r e c u r r e n t g r o u p s com pared to th e A m p h io d ia - C a r d i t a a s s o c i a t i o n ( 3 . 4 g r o u p s / s a m p l e ) . I n th e N o t h r i a -T e l l i n a a s s o c i a t i o n G ro u p s N - I I I and N-IV w e re n o t c o l l e c t e d ; G roups N-I ( 2 o f 18 sa m p le s f o r 11 p e r c e n t ) and N-V (5 o f 18 f o r 28 p e r c e n t ) w e re p o o r ly r e p r e s e n t e d in t h i s a s s o c i a t i o n . O c c u r r i n g a t i n t e r m e d i a t e f r e q u e n c i e s were G roups N -IV (8 o f 18 s a m p le s , 44 p e r c e n t ) and N - I I (9 o f 1 8 , 50 p e r c e n t ) . O n ly Group N -V III was w e l l d i s t r i b u t e d i n t h i s a s s o c i a t i o n ; i t was p r e s e n t i n 14 o f 18 s a m p le s (7 8 p e r c e n t ) . Group N -V III w as n o t e n c o u n t e r e d i n sa m p les fro m e i t h e r o f th e o t h e r two m ajo r a s s o c i a t i o n s o f t h i s a r e a . The mean number o f g r o u p s p er sam p le i n th e N o t h r i a - T e l l i n a a s s o c i a t i o n i s 2 . 1 . The r e c u r r e n t g ro u p a n a l y s i s o f t h e n o r t h e r n s h e l f sam ple s u b s e t p r o d u c e s g r o u p s t h a t i n c e r t a i n c o m b in a tio n s a p p r o x im a te th e a s s o c i a t i o n s p r e v i o u s l y d e f i n e d i n t h i s r e g io n by c l a s s i c a l m e th o d s. However, t h e c o r r e s p o n d e n c e b e tw een t h e a s s e m b la g e s d e v e l o p e d by t h e s e two a p p r o a c h e s i s i m p e r f e c t . Such a w e l l - d e f i n e d a s s o c i a t i o n a s th e L i s t r i o lo b u s a s s o c i a t i o n w ith i t s p a r t i c u l a r e n v ir o n m e n t f a i l s to a p p e a r a s an u n e q u i v o c a l e n t i t y a s a r e s u l t o f t h i s t y p e o f 247 a n a l y s i s . F u r t h e r r e d u c t i o n o f t h e r e g i o n under c o n s i d e r a t i o n may b e w a r r a n te d i f th e r e c o g n i t i o n o f such a d i s c r e t e f a u n a l a s s o c i a t i o n i s t h e g o a l . The S a n ta B a r b a r a S h e l f (A re a I I ) R e c u r r e n t G ro u p s I n an e f f o r t t o r e l a t e t h e g ro u p s d e r i v e d b y th e r e c u r r e n t g ro u p a n a l y s i s m ethod (REGROUP) more d i r e c t l y w i t h t h e c l a s s i c a l l y d e f i n e d b e n t h i c a s s o c i a t i o n s , th e f o c u s o f t h e t e c h n i q u e w as f u r t h e r n a r ro w e d . The t o p 200 s p e c i e s a s ra n k e d by f r e q u e n c y i n t h e 1 7 6 -sa m p le s e t c o l l e c t e d i n th e 41 s a m p le s fro m A re a I I , t h e S a n ta B a r b a r a s h e l f , w e re a n a ly z e d by t h e r e c u r r e n t g r o u p m ethod. Of t h e s e s p e c i e s , 62 showed a f f i n i t y w i t h o t h e r s p e c i e s when th e a f f i n i t y i n d e x was s e t a t 0 . 6 5 0 ; t h e s e 62 i n c l u d e d 24 p o l y c h a e t e s , 26 c r u s t a c e a n s (16 a m p h ip o d s, 3 o s t r a c o d s , 2 i s o p o d s , 2 cum aceans, 2 d e c a p o d s and 1 t a n a i d ) , 7 m o llu s k s ( a l l p e l e c y p o d s ) , 2 e c h in o d e rm s ( b o t h o p h i u r o i d s ) an d t h r e e from o t h e r s y s t e m a t i c c a t e g o r i e s . F o r t y - n i n e o f t h e s e s p e c i e s c o u ld be a r r a n g e d i n 18 g r o u p s ; th e r e m a i n in g 13 s p e c i e s had a f f i n i t i e s w i t h some, b u t n o t a l l , of t h e members o f one o r more o f t h e s e g r o u p s . T a b le 14 p r e s e n t s t h e 18 r e c u r r e n t g r o u p s and l i s t s ( 1) t h e s p e c i e s c o n s t i t u t i n g e a c h g r o u p , ( 2) th e s p e c i e s sho w in g a f f i n i t y to p a r t i c u l a r g r o u p s , ( 3 ) t h e g ro u p a f f i l i a t i o n s o f th e s p e c i e s , i f any, i n th e r e c u r r e n t g ro u p s r e s u l t i n g fro m t h e a n a l y s i s o f th e 248 T a b le 14- The R e c u r r e n t G roups o f th e S a n t a B a r b a r a S h e l f B ased on t h e A n a l y s i s o f th e 176-Sam ple S e t , I . A . = 0 . 6 5 0 . R e c u r r e n t G roups O c c u r re n c e A f f i n i t i e s GROUP S B - I : *A m phiodia u r t i c a , N -I 40 26 * P e c t i n a r i a c a l i f o r n i e n s i s , N -I 37 23 * P r i o n o s p i o p i n n a t a , N -I 38 21 * C o s s u ra C a n d id a , N -I 32 17 T e r e b e l l i d e s s t r o e m i , N -I 30 17 * S t e r n a s p i s f o s s o r , N -I 29 15 G n a t h i a c r e n u l a t i f r o n s , N -I 27 18 * P a r a o n i s g r a c i l i s , N - I I 30 16 * P h o lo e g l a b r a , N -I 28 15 * A x in o p s id a s e r r i c a t a , N -I 25 13 A s s o c i a t e d w i t h GROUP S B -I: E u d o r e l l a A, A -I 17 2 P h o t i s l a c i a 16 1 L a o n ic e c i r r a t a , A - I , I I 22 3 * S p io p h a n e s m i s s i o n e n s i s , A - I , I I , I I I 24 2 G o n iad a b r u n n e a , A - I , I I , I V 25 5 H a lio p h a s m a g e m in a ta 22 8 GROUP S B - I I : * n e m e r te a n unknown, N - I I 34 16 * A m p h ip h o lis s q u a m a ta , N-IV 28 8 * P r i o n o s p i o m a lm g re n i, N -II 28 8 249 Table 14 (Cont.) R e c u r r e n t Groups O c c u rre n c e A f f i n i t i e s A s s o c i a t e d w i t h GROUP S B - I I : G o n ia d a b r u n n e a , A - I , I I , I V 25 2 GROUP S B - I I I : * H e te ro p h o x u s o c c u l a t u s 27 14 * G l y c e r a c a p i t a t a , N -I 23 12 N e p h ty s f e r r u g i n e a , A - I , I I 24 11 A s s o c i a t e d w i t h GROUP S B - I I I : H a lio p h a sm a g e m in a ta 17 1 GROUP S B -V I: N u c u la n a t a p h r i a , V II 24 6 Macoma y o l d i f o r m i s 17 4 P i s t a d i s j u n c t a 21 3 A s s o c i a t e d w i t h GROUP SB-IV : e n t e r o p n e u s t s unknown, V II 19 1 M ag elo n a p a c i f i c a 16 1 C a l l i a n a s s a s p . 14 1 GROUP SB-V: * t a n a i d unknown 25 11 A m p e lis c a p u g e t i c a 17 4 D i a s t y l i d a e unknown 18 3 Table 14 (Cont.) R e c u r r e n t G roups O c c u r re n c e A f f i n i t i e s GROUP S B -V I: T h a l e n e s s a s p i n o s a , N-XI 11 3 P a ra p h o x u s f a t i g a n s , N -X II 9 3 N e p h ty s c a e c o i d e s , N-XI 8 2 GROUP S B -V II: Compsomyax s u b d ia p h a n a , A - I , I I 24 9 * A m p e lisc a b r e v i s i m u l a t a 29 13 A s s o c i a t e d w i t h GROUP S B -V II: * G l o t t i d i a a l b i d a 16 1 H a lio p h a s m a g e m in a ta 22 8 GROUP S B - V I II : P i n n i x a s p . 26 6 ■^ostracod unknown 26 6 GROUP SB-IX : ^ A m p e lis c a c r i s t a t a 21 4 A x i o t h e l l a r u b r o c i n c t a 23 3, GROUP SB-X: L i s t r i e l l a g o l e t a 20 2 N e r e i s p r o c e r a 19 1 A s s o c i a t e d w i t h GROUP SB-X: P o e c i l o c h a e t u s j o h n s o n i 18 3 251 Table 14 CCont.) R e c u r r e n t G roups O c c u rre n c e A f f i n i t i e s GROUP SB-XI: A m p e lisc a p a c i f i c a 19 6 C a r d i t a v e n t r i c o s a 17 1 GROUP S B -X II: A m p e lis c a c o m p re s s a , N-V 18 2 L o im ia m edusa 17 1 GROUP S B - X I I I : ^ P a r a p h o x u s s i m i l i s 15 2 C h l o e i a p i n n a t a 16 1 GROUP SB-XIV: T e l l i n a b u t t o n ! , N -V III 16 3 C h a e to z o n e c o r o n a , N -V III 12 1 GROUP SB-XV: brown o s t r a c o d , N-X 14 1 r e c t a n g u l a r o s t r a c o d , N-X 14 1 GROUP SB-XVI: A m p e lis c a m a c r o c e p h a la 11 1 P h o x c e p h a lu s h o m i l i s 9 1 252 Table 14 CCont.) R e c u r r e n t Groups GROUP SB-XVII: L y s i a n a s s a h o lm e s i P a ra p h o x u s r o b u s t u s O c c u r re n c e A f f i n i t i e s 8 6 1 1 GROUP S B -X V III: H em ilam p ro p s c a l i f o r n i c a 5 1 P a ra p h o x u s v a r i a t u s 7 2 * = Common t o T a b le 4 Roman n u m e r a ls i n d i c a t e a f f i l i a t i o n and a s s o c i a t i o n o f s p e c i e s w i t h g r o u p s d e f i n e d in t h e r e c u r r e n t group a n a l y s i s o f t h e N o r t h e r n s h e l f . 253 N o r t h e r n s h e l f , (4 ) th e number o f o c c u r r e n c e s o f e a c h s p e c i e s i n th e 4 1 -sa m p le s u b s e t , ( 5 ) th e number o f a f f i n i t i e s th e s p e c i e s h a s w ith o t h e r s p e c i e s , and ( 6 ) th e s p e c i e s common t o T a b le 4 a s i n d i c a t e d b y an a s t e r i s k . N e a r ly h a l f (5 o f 12) o f t h e r e c u r r e n t g r o u p s d e r i v e d b y t h e a n a l y s i s o f th e 7 4 -s a m p le n o r t h e r n s h e l f sam p le s u b s e t la c k e d any i n t e r - g r o u p c o n n e c t i o n s . I n c o n t r a s t , 15 o f th e 18 g ro u p s o f t h e S a n ta B a r b a r a s u b s e t h a d l i n k s w ith one o r more g r o u p s . The d ia g r a m m a tic r e p r e s e n t a t i o n o f t h e i n t e r - g r o u p r e l a t i o n s h i p s i s r a t h e r c o m p l i c a t e d ; t h i s d ia g r a m i s shown i n F ig u r e 6 3 . I n t e r - g r o u p c o n n e c t i o n s i n d i c a t e t h a t t h e s p e c i e s o f one g ro u p have some a f f i n i t i e s w ith t h e s p e c i e s o f t h e o t h e r g ro u p ; th e f r a c t i o n s a d j a c e n t t o e a c h i n t e r - g r o u p l i n k a r e th e r a t i o s o f th e o b s e rv e d i n t e r - g r o u p a f f i n i t i e s ( s p e c i e s - p a i r s w ith a f f i n i t i e s ) to th e maximum p o s s i b l e i n t e r - g r o u p a f f i n i t i e s . T h e re i s a c e n t r a l c l u s t e r o f g ro u p s r e l a t e d to t h e SB-I and S B -II g ro u p s t h a t i n c l u d e s G roups S B - V I I I , SB-X and SB-V and S B -V II. One o r more members o f g r o u p s SB-V, - V I I , - V I I I and SB-X w ere members o f or a s s o c i a t e d w i t h G roups I and I I o f t h e e n t i r e s h e l f sam ple s e t , and th e S a n ta B a r b a r a s h e l f g r o u p s SB-I and S B -II c o n t a i n e s s e n t i a l l y th e same e l e m e n t s a s G ro u p s I and I I f o r t h e e n t i r e s h e l f . G roup S B - I I I i s more c l o s e l y l i n k e d to S B -I ( 2 6 /3 0 , 87 p e r c e n t ) th a n any o t h e r g r o u p . The 3 s p e c i e s o f Group Figure 63 A D ia g ra m m a tic R e p r e s e n t a t i o n o f t h e I n t e r - r e l a t i o n s h i p o f t h e R e c u r r e n t G roups o f t h e S a n t a B a r b a r a S h e l f B ased on I n t e r - G r o u p A f f i n i t i e s . The f r a c t i o n s a r e th e r a t i o s o f t h e o b s e r v e d i n t e r - g r o u p a f f i n i t i e s to t h e maximum p o s s i b l e i n t e r - g r o u p a f f i n i t i e s . I n t h i s f i g u r e t h e l i n e s a r e n o t p r o p o r t i o n a l t o th e i n v e r s e o f t h e s e v a l u e s a s th e f i g u r e c o u ld n o t b e so c o n s t r u c t e d w i t h o u t th e u s e o f c u rv e d l i n e s . 254 SB m SB SB SB 1 /9 1/9 3 /9 26/30 i/30 'S B z m m n SB m u SB SB 1/6 2/2 SB IX SB SB TTTT 1/20 1/4 10/20 2 /3 0 SB 1/6 tN J U\ L n Figure 63 256 S B - I I I w ere e i t h e r p a r t o f or a f f i l i a t e d w i t h G roups I or I I I o f th e e n t i r e s h e l f r e c u r r e n t g ro u p a n a l y s i s . Group S B - I I I i s w e a k ly l i n k e d C l / 9 = 11 p e r c e n t ) t o G roup S B - I I . W ith G roup S B - I I I , G roups SB-XI ( s i n g l e c o n n e c t i o n t o Group S B -I) and S B -X III form a c l u s t e r . C a r d i t a v e n t r i c o s a i s a member o f Group SB-XI. G roup SB-XI i s l i n k e d to G roup SB-I by 10 p e r c e n t o f th e p o s s i b l e s p e c i e s - p a i r a f f i n i t i e s . S p e c i e s o f b o th G roups IX and X I I I , l i k e t h o s e o f S B - I I I , i n c l u d e members o f th e t h i r d g ro u p p r o d u c e d i n th e a n a l y s i s o f th e 1 7 6 -sa m p le s e t . Groups SB-XIV, VI and X V III ( s i n g l e c o n n e c t i o n to SB-VI) form a u n i t c o n n e c te d to a l l o f th e r e m a in in g g ro u p s o n ly b y two l i n k s (SB-VI t o S B - I I I and SB-XIV t o I X ) . T h is u n i t o f g ro u p s i s of i n t e r e s t b e c a u s e Group SB-XIV i n c l u d e s as a member T e l l i n a b u t t o n i , " c o - d o m in a n t" w i t h N o t h r i a e l e g a n s i n th e N o t h r i a - T e l l i n a a s s o c i a t i o n . Groups SB-IV and S B -X II, c o n n e c te d by a s i n g l e l i n k to SB -IV , c o u ld be c o n s i d e r e d to fo rm a u n i t ; SB-IV i s l i n k e d t o S B -I, SB-VII an d SB-IX. Group SB-XI c o n n e c t s o n ly w i t h SB-IV. Group SB-IX h a s n o t b e e n i n c l u d e d i n any o f t h e s e 4 u n i t s a s i t seem s to be w e a k ly l i n k e d ( s i n g l e s p e c i e s - p a i r a f f i n i t y ) t o e a c h o f t h e g r o u p s ( S B - I , S B - I I , SB-IV and SB-XIV) to w h ic h i t c o n n e c t s . The g e o g r a p h i c p a t t e r n o f g ro u p s SB-I to SB-VI, SB-X, SB-XI and SB-XIV w as exam ined by p l o t t i n g t h e i r o c c u r r e n c e a t t h e sa m p lin g l o c a t i o n s a t w h ic h t h e y w ere 257 c o l l e c t e d . To im prove t h e c o v e r a g e o f t h i s a r e a , 24 a d d i t i o n a l c o m p le te ly s o r t e d s a m p le s w ere i n c l u d e d w ith t h e 41 s a m p le s o f t h e S a n ta B a r b a r a s u b s e t ( F ig u r e 6 4 ) . G roup S B -I was c o n s i d e r e d p r e s e n t i f 8 o r more o f i t s 10 s p e c i e s w ere p r e s e n t i n a s a m p le . G ro u p s S B -II t o SB -V I, SB-X, SB-XI and SB-XIV had t o be p r e s e n t as c o m p le te u n i t s . I n a d d i t i o n t o t h i s i n f o r m a t i o n t h e t h r e e m a jo r b e n t h i c a s s o c i a t i o n s o f t h i s r e g i o n , th e A m p h io d ia -C a r d i t a a s s o c i a t i o n , t h e L i s t r i o l o b u s a s s o c i a t i o n and t h e N o t h r i a - T e l l i n a a s s o c i a t i o n , a r e mapped b a s e d on t h e a s s o c i a t i o n d e s i g n a t i o n s a s s i g n e d to t h e s e 65 s a m p le s (A p p e n d ix T a b le A - 3 ) . D i r e c t c o m p a riso n o f th e d i s t r i b u t i o n s o f th e r e c u r r e n t g r o u p s and t h e s e a s s o c i a t i o n s can be made b y e x am in in g t h i s map. The f o l l o w i n g p a t t e r n s e m e rg e . G roup SB-I i s p r e s e n t a t a l l 16 sa m p lin g l o c a t i o n s i n th e A m p h io d ia - C a r d i t a a s s o c i a t i o n . Group SB-XI was c o l l e c t e d a s a u n i t i n n e a r l y e v e r y sam ple ( a b s e n t fro m 2 o f 16 s a m p le s) fro m t h i s a s s o c i a t i o n ; t h i s g roup a l s o o c c u r r e d i n 2 s a m p le s a t th e j u n c t i o n b etw een t h e A m p h io d ia - C a r d i t a a s s o c i a t i o n and t h e L i s t r i o l o b u s a s s o c i a t i o n and i n 3 sam p les w i t h i n th e L i s t r i o l o b u s a s s o c i a t i o n ; t h e s e 3 sam p les w i t h i n t h i s a s s o c i a t i o n w ere c o l l e c t e d a t l o c a t i o n s alo n g i t s d e e p e r o u t e r edge a d j a c e n t t o th e A m p h io d ia - C a r d i t a a s s o c i a t i o n . G roup S B - I I I i s a l s o p r o m in e n t (10 o f 16 sa m p le s) w i t h i n t h e A m p h io d ia - C a r d i t a a s s o c i a t i o n . G roup SB-V i s r e s t r i c t e d to t h e o u t e r p o r t i o n o f t h e s h e l f and was c o l l e c t e d a t a Figure 64 The G e o g ra p h ic D i s t r i b u t i o n of th e R e c u r r e n t G ro u p s o f t h e S a n ta B a r b a r a S h e l f fro m S a n t a B a r b a r a t o Hueneme Subm arine Canyon ( S a n t a B a r b a r a t o M ugu). 258 STA. BARBARA STA. BARBARA TO MUGU CARPI NTEZRIA STATUTE MILES Cl STATUTE MILE • I S O * KILOM ETERS) ^ V S O O P O O T ( S I .4 M E T E R ) CONTOUR PT. L A S P I T A S V E N T U R A *7 t l y \ L s f * \ ° ° i □ \ N __: A? \ 4 \ \ ' a - A ! o RECURRENT; GROUPS PO R T HUENEME S B - I s b - h l o j ; ^ S B -m HUCW L A COO A S B - 12 S B -IE S B -2 1 ■ S B - ZS s b - m A M P H I0 0 1 A -C A R D IT A ----------- L1STRIOLOBUJ NOTHRIA - TEI .LINA C O Lr, v O Figure 64 260 number o f l o c a t i o n s (7 o f 16) i n t h i s a s s o c i a t i o n . G roups SB-VI and SB-XIV w ere n o t p r e s e n t a s c o m p le te u n i t s i n an y o f th e s a m p le s c o l l e c t e d from th e A m p h io d ia - C a r d i t a a s s o c i a t i o n . G roups S B -I (10 o f 14 s a m p l e s ) , S B - I II (7 o f 14 s a m p le s ) and SB-X (8 o f 14 s a m p le s ) a r e th e m ost f r e q u e n t l y o c c u r r i n g g ro u p s i n sa m p le s from th e L i s t r i o l o b u s a s s o c i a t i o n . T h e se t h r e e g ro u p s i n c l u d e a s members o r a s a s s o c i a t e d s p e c i e s 4 o f t h e 6 s p e c i e s t h a t c o r r e l a t e ( P e a r s o n Ts p ro d u c t-m o m e n t c o r r e l a t i o n ) a t th e 0 .4 0 0 l e v e l or above w i t h L i s t r i o l o b u s p e l o d e s . One o f t h e s e s p e c i e s , th e am phipod L i s t r i e l l a g o l e t a ( 0 . 4 8 3 ) , i s a member o f Group SB-X; t h e p o l y c h a e t e P o e c i l o c h a e t u s .jo h n so n i ( 0 .4 5 3 ) h a s a f f i n i t y o n ly w i t h Group SB-X. The o t h e r two s p e c i e s a r e members o f Group S B -I ( t h e p o l y c h a e t e T e r e b e l l i d e s s t r o e m i , 0 .4 6 1 ) an d Group S B - I I I ( t h e amphipod H e te ro p h o x u s o c c u l a t u s , 0 . 4 5 7 ) . Two g r o u p s , Groups SB-VI and SB-XIV, w ere n o t c o l l e c t e d a s u n i t s i n any o f th e s a m p le s fro m th e L i s t r i o l o b u s a s s o c i a t i o n . The d i s t r i b u t i o n o f Group SB-XIV c o r r e s p o n d s a s a u n i t t o t h e N o t h r i a - T e l l i n a a s s o c i a t i o n . I t o c c u r s a t a l l b u t 3 o f 18 ( 1 6 .7 p e r c e n t ) sa m p lin g l o c a t i o n s e s t a b l i s h e d i n t h i s a s s o c i a t i o n . G roup S B -II i s p r e s e n t a t 14 o f t h e 18 s t a t i o n s . G roup SB-VI i s a t 50 p e r c e n t o f t h e s e l o c a t i o n s . G roups S B - I I I , SB-V and SB-XI a r e l a c k i n g as com p l e t e u n i t s i n t h e s a m p le s c o l l e c t e d i n t h e N o t h r i a - T e l l i n a 261 a s s o c i a t i o n ; G roup S B -I i s p o o r l y r e p r e s e n t e d (4 o f 18 sam p l e s ) . A summary o f t h e g ro u p d i s t r i b u t i o n s i n t h e 3 m ajo r b e n t h i c a s s o c i a t i o n s i s g iv e n i n T a b le 15; o n ly t h e g ro u p s mapped i n F i g u r e 64 a r e i n c l u d e d . I t i s a p p a r e n t t h a t th e c o m b in a tio n o f g ro u p s i n s a m p le s fro m th e A m p h io d ia - C a r d i t a a s s o c i a t i o n and L i s t r i o l o b u s a s s o c i a t i o n a r e s i m i l a r ^ Both o f t h e s e c o m b in a tio n s d i f f e r from t h e c o m b in a tio n o f g ro u p s i n s a m p le s fro m th e N o t h r i a - T e l l i n a a s s o c i a t i o n . T a b le 15. Summary o f G roup D i s t r i b u t i o n by M ajor A s s o c i a t i o n s on S a n ta B a r b a r a S h e l f ; O n ly G roups SB-I t o SB-VI, SB-X, SB-XI and SB-XIV. (+ = p r o m i n e n t ; P = p r e s e n t b u t n o t p r o m in e n t; 0 = a b s e n t ) GROUPS I I I I I I IV V VI X XI XII A m p h i o d i a - C a r d it a + P + p 4* 0 p + 0 L i s t r i o l o b u s + P + p p 0 + p 0 N o t h r i a - T e l l i n a P + 0 p 0 + p 0 4* The g e o g r a p h i c p a t t e r n s o f d i s t r i b u t i o n o f G roups SB-X, SB-XI and SB-XIV a r e o b v i o u s l y d i f f e r e n t and o v e r l a p o n ly s l i g h t l y . I t can be e x p e c te d t h a t t h e i r e n v ir o n m e n ts w i l l v a r y . T a b le 16 p r e s e n t s a summary o f th e means and r a n g e s o f th e e n v i r o n m e n t a l v a r i a b l e s m ea su re d a t th e 41 sa m p lin g l o c a t i o n s i n A re a I I . The e n v iro n m e n t o f G roup SB-XI i s c h a r a c t e r i z e d by d e e p w a t e r and by f i n e , somewhat p o o r l y s o r t e d s e d im e n ts w i t h r e l a t i v e l y h ig h o r g a n i c T a b le 16. Summary o f th e E n v ir o n m e n ta l and S t a n d in g Crop V a r i a b l e s f o r Groups SB-XI, SB-X, and SB-XIV D e riv e d fro m th e R e c u r r e n t Group A n a l y s i s o f th e Sam ples from th e S a n ta B a r b a r a S h e l f . V a r i a b l e s Group SB-XI Group SB-X Group SB-XIV D e p th , i n m e te r s 7 9 .0 3 7.6 20.1 4 4 .2 - 1 0 2 .1 1 1 .9 - 9 4 .8 1 1 .9 - 2 7 .2 Sand C o n t e n t , (%) 1 6 .4 1 4.6 3 7 .4 0 .3 5 - 7 1 .5 6 1 .9 7 - 3 2 .5 7 2 2 .2 6 - 9 7 .2 0 S i l t C o n te n t, (%) 66.0 7 4 .0 5 7 .8 1 9 .1 9 - 9 1 .4 3 5 7 .5 4 - 8 7 .5 2 2 .8 0 - 9 3 .5 4 C lay C o n t e n t , (%) 1 7 .4 11.1 4 .2 3 .6 9 - 5 1 .4 8 3 .4 6 - 2 3 .7 6 0 .0 - 1 4 .7 0 M edian D ia m e te r , mm. 0 .0 3 3 0 .0 3 4 0 .0 5 7 0 . 0 0 8 - 0 .0 9 5 0 . 0 1 3 - 0 .0 5 2 0 .0 3 9 - 0 .0 9 2 S o r t i n g C o e f f i c i e n t 2 .5 5 (w /o ***, 2 .1 0 ) 1 .8 4 1.33 1 .1 8 -8 .2 8 * * * 1 .1 1 - 3 .6 1 1 .1 1 - 1 .8 4 N i t r o g e n C o n te n t, C%) 0 .0 6 2 0 .0 6 6 0 .0 3 4 0 .0 0 1 - 0 .1 2 6 0 . 011- 0.122 0 . 011- 0.100 CaCOo C o n t e n t , (%) 3 .9 8 3 .1 7 2 .9 1 o 1 . 7 - 1 0 . 4 1 . 6 - 5 . 9 1 . 1 - 5 . 9 P o l y c h a e t e s , w. w g t. 1 4 .2 3 0 .5 21.2 5 . 3 - 3 2 . 0 5 . 7 - 8 5 . 2 4 . 0 - 8 5 . 2 to o to T a b le 16 C C ont.) V a r i a b l e s E c h in o d e rm s, w. w g t. M o llu s k s , w. w g t. L i s t r i o l o b u s , w. w g t. O th e r T a x a; w. w g t. Group SB-XI 20 .8 0 . 3 - 9 3 . 8 1 0 .3 0 . 4 - 3 5 . 3 8 .7 0 . 3 - 1 1 2 . 1 1 3 .6 0 . 2 - 1 1 5 . 9 16 sa m p les Group SB-X Group SB-XIV 4 .8 0 . 1 - 1 7 . 8 1 6 .0 1 . 6 - 5 2 . 8 4 9 .3 0 . 0 - 2 9 . 1 5 5 .9 0 . 3 - 3 0 . 7 20 sam p les 0 .7 0 . 0 - 8.9 1 6 .1 0 . 3 - 5 2 . 8 4 .8 0 . 0 - 3 2 . 0 6 .5 0 . 0 - 3 2 . 0 12 sam p les 263 264 n i t r o g e n c o n t e n t . The s t a n d i n g c r o p o f e c h in o d e rm s i s h ig h a s would b e e x p e c te d f o r sam p les c o l l e c t e d i n a l a r g e p a r t o f th e A m p h io d ia- C a r d i t a a s s o c i a t i o n . I n some r e s p e c t s th e e n v iro n m e n t o f G roup SB-X i s s i m i l a r t o t h a t o f Group SB-XI. G roup SB-X i s d i s t r i b u t e d on b o tto m s a t i n t e r m e d i a t e d e p t h s . S e d im e n ts a t t h e s e l o c a t i o n s a r e f i n e b u t somewhat b e t t e r s o r t e d t h a n t h o s e a t Group XI sa m p lin g l o c a t i o n s . The mean o r g a n i c n i t r o g e n c o n t e n t o f th e s e d im e n ts w here G roup SB-X was c o l l e c t e d i s n e a r l y i d e n t i c a l to t h a t o f th e SB-XI l o c a t i o n s . The mean ec h in o d e rm s t a n d i n g c ro p i s low. The L i s t r i o l o b u s s t a n d i n g c ro p mean i s h i g h ; t h e s e f i g u r e s r e f l e c t th e a s s o c i a t i o n a f f i l i a t i o n o f t h e s e g r o u p s . The Group SB-XIV e n v iro n m e n t i s c h a r a c t e r i z e d by s h a llo w e r w a te r ( ra n g e 1 1 .9 to 2 7 .2 m e te r s ) and c o a r s e r (mean, 0 .0 5 7 mm), b e t t e r s o r t e d (m ean, 1 .3 3 ) s e d im e n ts th a n e i t h e r o f th e o t h e r g r o u p s . The o r g a n i c n i t r o g e n c o n t e n t o f th e s e d im e n ts a t t h e sa m p lin g l o c a t i o n s w here Group SB-XIV was c o l l e c t e d a v e ra g e d 0 .0 3 4 p er c e n t low er t h a n t h i s v a r i a b l e f o r t h e o t h e r two g r o u p s . E c h in o d e rm and L i s t r i o l o b u s s t a n d i n g c ro p v a l u e s w ere low i n t h e s e sam ples. M o llu s k s t a n d i n g c ro p v a l u e s were h i g h . NTSYS r - M a t r i x C l u s t e r A n a l y s i s REGROUP, th e r e c u r r e n t g ro u p a n a l y s i s j u s t d e s c r i b e d , i s b a s e d on t h e c o - o c c u r r e n c e o f s p e c i e s i n th e 265 s a m p le s o f a s e t . A c o n t r a s t i n g m e th o d , t h e NTSYS £ - m a t r i x c l u s t e r a n a l y s i s , i s a p p l i e d t o s p e c i e s p o p u l a t i o n d e n s i t y i n f o r m a t i o n a s e s t i m a t e d by t h e s a m p le s o f su ch a s e t . I t s a p p l i c a t i o n t o t h e d a t a o f th e p r e s e n t s tu d y w i l l be d e s c r i b e d i n t h i s s e c t i o n . The c o m b in a tio n o f co m p u te r p r o gram s (INPUT, OUTPUT, CORDST, TAXON and MXCOMP) u s e d i n t h i s i n v e s t i g a t i o n a r e p a r t of a m u l t i v a r i a t e s t a t i s t i c a l p ro g ra m p a c k a g e w r i t t e n by R o h lf and K is h p a u g h ( 1 9 6 6 ) . The p ro g ra m s h av e b e e n d e s c r i b e d b r i e f l y i n t h e s e c t i o n on d a t a - p r o c e s s i n g m e th o d s . C l u s t e r a n a l y s i s h a s b e e n a p p l i e d i n t h e m ain t o p ro b le m s i n th e f i e l d o f n u m e r i c a l taxonom y ( S o k a l and S n e a th , 1 9 6 3 ) . As S o k a l (1 9 6 6 , p . 106) h a s p o i n t e d o u t , " C l a s s i f i c a t i o n i s one o f t h e f u n d a m e n ta l c o n c e r n s o f s c i e n c e . . . " The m eth o d s d e v e lo p e d by t h e n u m e r i c a l t a x o n o m i s t s c a n and w i l l be a p p l i e d to th e a n a l y s i s o f o th e r t y p e s o f com plex s y s t e m s . C e r t a i n z o o g e o g r a p h ic and e c o l o g i c a l p ro b le m s a r e w e l l s u i t e d t o t r e a t m e n t b y t h e s e m e th o d s. V a l e n t i n e (1 9 6 6 ) a n a ly z e d t h e g e o g r a p h i c r a n g e s o f m o llu s k s by a s i m i l a r n u m e r ic a l t e c h n i q u e and u s e d th e r e s u l t s t o d e f i n e a new s y ste m o f P a c i f i c C o a s t M arin e P r o v i n c e s . E b e lin g and L a v e n b e rg ( p e r s . comm.) a r e u s in g t h e NTSYS c l u s t e r a n a l y s i s p ro g ra m s to e v a l u a t e e c o l o g i c a l g r o u p s o f m e s o p e la g ic and b a t h y p e l a g i c f i s h e s and i n v e r t e b r a t e s c o l l e c t e d fro m d e e p b a s i n s o f t h e s o u t h e r n ' C a l i f o r n i a n b o r d e r l a n d . 266 When em ployed i n n u m e r i c a l taxonom y t h i s method g ro u p s " o p e r a t i o n a l ta x o n o m ic u n i t s " o r OTU’s ( r e p r e s e n t i n g i n d i v i d u a l s p e c im e n s , s p e c i e s or h i g h e r t a x a ) on th e b a s i s o f th e i n f o r m a t i o n p r o v id e d b y many n u m e r i c a l l y r e c o r d e d c h a r a c t e r s . The c h a r a c t e r s and th e ta x o n o m ic u n i t s t o be c l a s s i f i e d a r e i n p u t to th e c o m p u ter ( u s u a l l y i n p u n c h - c a r d form ) as a d a t a m a t r i x . S i m i l a r i t i e s , t y p i c a l l y P e a r s o n p ro d u c t-m o m e n t c o r r e l a t i o n c o e f f i c i e n t s ( r ) , a r e c a l c u l a t e d b e tw e e n a l l p o s s i b l e p a i r s o f OTU’s on th e b a s i s o f a l l c h a r a c t e r s . The c o e f f i c i e n t s a re a r r a n g e d i n a " s i m i l a r i t y m a t r i x . " Such a m a t r i x can b e e v a l u a t e d by t h e co m p u ter by s e v e r a l m e th o d s and p r o j e c t e d i n th e fo rm o f a t r e e - l i k e d ia g ra m , a d e n d ro g ra m ( S o k a l and S n e a t h , 1963; S o k a l, 1 9 6 6 ). The NTSYS C l u s t e r A n a l y s i s o f t h e N o r t h e r n S h e l f S p e c ie s I n e c o l o g i c a l i n v e s t i g a t i o n s s u c h a s t h i s s t u d y , th e s p e c i e s a r e t h e OTU’s , e a c h sam ple i n w h ic h th e s p e c i e s were c o l l e c t e d i s c o n s i d e r e d a s e p a r a t e " e c o l o g i c a l c h a r a c t e r , " and th e number o f s p e c im e n s of e a c h s p e c i e s a t e a c h s a m p lin g l o c a t i o n a re t h e " m e a s u re m e n ts ” o f t h e s e c h a r a c t e r s ( s a m p l e s ) . In t h i s s tu d y t h e 200 m ost f r e q u e n t s p e c i e s i n t h e 1 7 6 -sa m p le s e t as c o l l e c t e d i n th e 74 samples from A r e a s I , I I and I I I ( t h e N o r t h e r n S h e l f ) w ere a n a ly z e d b y t h i s m e th o d . An r_ v a lu e i s c a l c u l a t e d f o r e a c h p a i r o f s p e c i e s . F o r th e 200 s p e c i e s OTU’s u s e d i n t h i s a n a l y s i s t h e o r i g i n a l t r i a n g u l a r " s i m i l a r i t y m a t r i x " c o n t a i n e d 1 9 ,9 0 0 £ v a l u e s . The r e s u l t s o f t h e c l u s t e r a n a l y s i s o f th e o r i g i n a l - m a t r i x and s u c c e e d in g m a t r i c e s ( a new m a t r i x i s c a l c u l a t e d a f t e r e a c h c l u s t e r i n g c y c l e ) w e re g r a p h i c a l l y p r e s e n t ed i n a co m p lex d en d ro g ra m r e l a t i n g t h e p o s i t i o n o f each s p e c i e s t o a l l t h e o th e rs.'* ' Once th e d e n d ro g ra m i s p r o d u c e d , g ro u p s a r e d e f i n e d by d ra w in g a v e r t i c a l l i n e a t a s e l e c t e d p o i n t a lo n g th e h o r i z o n t a l c o r r e l a t i o n c o e f f i c i e n t s c a l e . The p o s i t i o n o f t h e l i n e i s d e t e r m in e d by t h e ju d g m en t o f th e i n v e s t i g a t o r . O f t e n i t i s s e t a t an £ v a l u e o f 0 . 4 0 0 . I n t h i s i n v e s t i g a t i o n , b e c a u s e th e s p e c i e s w ere fra g m e n te d i n t o to o many s m a l l g r o u p s when t h e l i n e was t e n t a t i v e l y p l a c e d a t 0 . 4 0 0 , i t was s e t a t 0 .3 5 0 . (No a d v a n ta g e i n g r o u p in g would hav e b e e n g a i n e d by s h i f t i n g i t t o 0 .2 9 8 , th e 0 .0 1 l e v e l o f s i g n i f i c a n c e f o r an N o f 74 ( d . f . = 7 2 ) . Of th e 200 s p e c i e s 189 a r e i n c l u d e d i n 49 g ro u p s o f 2 o r more s p e c i e s d e l i m i t e d by t h e l i n e draw n a t an £ - v a l u e o f 0 .3 5 0 . T hese g r o u p s w ere a r r a n g e d i n f i v e m ain d e n d r i t i c b r a n c h e s and w i l l be i d e n t i f i e d by th e n u m b ers 1 to 5; t h e g r o u p s o f e a c h b r a n c h w i l l be i d e n t i f i e d b y low er c a s e ■ * " A c o p h e n e t i c c o m p a ris o n ( S o k a l and S n e a t h , 1963) b e tw e e n t h e d e n d ro g ra m and t h e o r i g i n a l r - m a t r i x i s p r o v id e d by p ro g ra m MXCOMP; how ever ^ f o r th T s num ber o f 0TUTs t h e d im e n s io n e d v a r i a b l e s n e e d e d w ould ex c e e d c o r e s t o r a g e o f th e IBM 7040. L i m i t a t i o n s o f tim e and money p r e v e n te d m a n i p u l a t i o n o f t h e p ro g ram t o overcom e t h i s d i f f i c u l t y . 268 l e t t e r s . T hus the f i f t h g ro u p on th e seco n d b r a n c h i s G roup 2 e . The r e l a t i v e p o s i t i o n o f a p a r t i c u l a r g ro u p or s p e c i e s i s a p p a r e n t i n i t s code number ( i . e . , G roups 4n and 4p a r e c lo s e t o g e t h e r and b o th a r e removed fro m 5 g ) . The g r o u p s formed by t h i s method o f a n a l y s i s w i l l be compared w i t h th o se d e te r m in e d by th e r e c u r r e n t g ro u p a n a l y s i s on th e b a s i s o f m u tu al s p e c i f i c com p o n en ts. Tw enty o f th e g ro u p s i n th e d en d ro g ram c o n s i s t o f o n ly two s p e c i e s ; e i g h t more i n c l u d e o n ly t h r e e s p e c i e s . O n ly seven g ro u p s c o n s i s t o f s e v e n s p e c i e s or m o re. I n t e r p r e t a t i o n o f th e p o s s i b l e b i o l o g i c a l s i g n i f i c a n c e o f th e s m a l l e r s p e c i e s c l u s t e r s r e q u i r e s f u r t h e r s t u d y . The o n ly g r o u p s of t h e d endrogram t h a t a r e d i s c u s s e d h e r e a r e t h o s e w h ic h can b e r e a d i l y r e l a t e d t o c l a s s i c a l f a u n a l a s s o c i a t i o n s . The f i r s t b r a n c h (B ra n c h One) h a s t h r e e g ro u p s . The a rra n g e m e n t o f s p e c i e s i n t h e s e g ro u p s c a n n o t be e a s i l y i n t e r p r e t e d on th e b a s i s o f p r e v i o u s know ledge o f th e fa u n a o f t h i s a r e a (A ppendix D); c o n s e q u e n t l y t h e y w i l l n o t be d i s c u s s e d h e r e . B ran ch Two i n c l u d e s 13 g r o u p s . The l a r g e s t , Group 2 c , i s composed o f 15 s p e c i e s i n c l u d i n g T e l l i n a b u t t o n i and N o th r ia e l e g a n s . A number o f th e o t h e r g ro u p s a l s o c o n t a i n s p e c i e s d i s t r i b u t e d i n s h a llo w w a t e r . B ranch T h r e e i s made up o f n i n e g r o u p s ; th e l a r g e s t h a s se v e n s p e c i e s , i n c l u d i n g D i o p a t r a o r n a t a . The o t h e r group., o f t h i s b r a n c h a r e n o t r e l a t e d i n any o b v io u s m anner to t h e c l a s s i c a l l y d e f i n e d u n i t s o f th e b e n t h i c m a c r o fa u n a o f t h e s h e l f . Hence t h e y a r e o m i t t e d from t h e p r e s e n t d i s c u s s i o n . On B ranch F our t h e r e a r e 16 g r o u p s . The m a jo r g ro u p , c o n t a i n in g 13 s p e c i e s , i n c l u d e s A m p h io d ia u r t i c a . An a d j a c e n t g ro u p o f e i g h t s p e c i e s i n c l u d e s C a r d i t a v e n t r i c o s a . A c l o s e l y p o s i t i o n e d g ro u p o f 12 s p e c i e s i n c l u d e s C h l o e i a p i n n a t a , P e c t i n a r i a c a l i f o r n i e n s i s , Amygdalum p a l l i d u l u m , and th e d e e p - w a t e r s p e c i e s A m p h ia c a n th a a m p h a c a n th a and T e l l i n a c a r p e n t e r i . Somewhat removed fro m t h e s e i s a tw o- s p e c i e s g ro u p t h a t i n c l u d e s Q n u p h is n e b u l o s a . B ra n c h F iv e h a s se v e n g r o u p s , two o f them i m p o r t a n t v ie w e d fro m th e s t a n d p o i n t o f t h e i r s i m i l a r i t y t o p r e v i o u s l y d e f i n e d a s s o c i a t i o n s . One g ro u p o f se v e n s p e c i e s i n c l u d e s L i s t r i o l o b u s p e l o d e s and S a x ic a v e 1 1 a p a c i f i c a . The o t h e r l a r g e ( 1 0 - s p e c i e s ) g ro u p on t h i s b r a n c h c o n t a i n s a number o f o t h e r s p e c i e s o f t e n c o l l e c t e d w ith L i s t r i o l o b u s . Group 2 c , T e l l i n a b u t t o n i and N o t h r i a e l e g a n s A p o r t i o n o f t h e se c o n d m ain b r a n c h o f th e d e n d r o gram i s p r e s e n t e d i n F ig u r e 6 5 . G roups 2 c , 21 and 2m a r e i n d i c a t e d . The OTU’ s a r e nam ed, and t h o s e t h a t w ere e l e m ents o f one o f th e r e c u r r e n t g ro u p s (REGROUP) a r e i d e n t i f i e d by t h e Roman n u m e ra l u s e d t o d e s i g n a t e t h e g r o u p . Figure 65 B ran ch Two o f t h e N o r t h e r n S h e l f D endrogram . 270 o .z z o o o.HBoo o.TH co 1 . 0 0 0 0 o t d i d . 0 .9 5 0 rnsi Hill BK1I0H SSCOK) m i l SHAWM , ,---------------------------------------------------------- ilo : I OROU? 2 o L--------- I.----- :--------------------------------- 135 ------------------------ i: u m o w i CHIB ! i ...................................... i p iB irm x u s v a h ia t u s, m I 1 ___ I . . . L----------------------------- i„ o Tgl.TMA BOTTOMI, T U I I I I 1 . - - i - - CHAMTOZOB COBOU, T i l l : i ! L- | - L------------------------------- :il" , B B O n CALITOHIICA , . ---------------- M u n a x D s * p i s » m i8 , n I I i . - i - - i>5 m u n a s i b p im o s a , x i 1 I i . — t ----------- m u p k o x u s s m r o m a , n ; i . — i. —L----------------------------- a; PAHAPHOXUS TATI(U»S, 111 1 ................ " ( t t o w n m ALHIDA l ------------------------------------------- u . MOHBIA E U U 1 R --------------------------------------- , t m g n m b a l ia m • :i- AMOTOHASIOS OOHDIODBS — — i x a n a x A w o t t a l l i ---------------------- --------- -------- , , HOJOOULODM HARHAIAB p ; • ! i i l — r • i . - i i :i: . n F ig u r e 65 1 jL i aj | ; 6;J i v to v rt z l . HAPtoaooLopLoa bloboatus 1 bA PBIOVOaPIO HALMSRBil, H ; d7 agonp , a OUTMLLA BABTICA l;;7 HABSIACTI3 S P . . AHPHIOTSla SCAPHOBBAIC HIATA : ad oo iia d a K t n r c s i , a m . i ( n , i t 71 ; 1 7 271 272 Group 2 c , th e l a r g e s t g ro u p on th e seco n d m ain b r a n c h o f th e d e n d ro g ra m , i n c l u d e s th e two " d o m in a n t" s p e c i e s o f th e N o t h r i a - T e l l i n a a s s o c i a t i o n ( B a r n a r d and H a r t man, 1959; B a r n a r d , 1 9 6 3 ). A lth o u g h N o t h r i a e l e g a n s and T e l l i n a b u t t o n i a r e s e p a r a t e d w i t h i n t h e g r o u p , th e c o r r e l a t i o n b etw een them i s s u b s t a n t i a l ; r_ = 0 .6 0 8 ( o r i g i n a l m a t r i x ) . Four o t h e r s p e c i e s i n th e g ro u p a l s o have h ig h c o r r e l a t i o n s w i t h T e l l i n a b u t t o n i : P a ra p h o x u s v a r i a t u s ( 0 . 7 2 1 ) , C h a e to z o n e c o r o n a ( 0 . 6 6 9 ) , P a ra p h o x u s s t e n o d e s ( 0 . 6 5 5 ) , and T h a l e n e s s a s p i n o s a ( 0 . 6 0 1 ) . E i g h t o f t h e r e m a in in g s p e c i e s i n th e g ro u p c o r r e l a t e w i t h T e l l i n a b u t t o n i a t v a l u e s b e tw e e n 0 .6 0 0 and 0 .4 0 0 . O nly a s i n g l e s p e c i e s , th e am phipod M o n o cu lo d es h a r t m a n a e , c o r r e l a t e s w i t h T e l l i n a b u t t o n i ( r = 0 . 2 9 7 ) belo w th e 0.01 l e v e l o f s i g n i f i c a n c e f o r 74 sa m p le s ( 0 . 2 9 8 ) . N o t h r i a e l e g a n s , t h e " c o - d o m in a n t" w i t h T e l l i n a b u t t o n i i n t h i s c l a s s i c a l l y d e f i n e d g r e y - s a n d a s s o c i a t i o n ( B a r n a r d and H a rtm a n , 1959; B a r n a r d , 1 9 6 3 ), d e m o n s t r a t e s a l e s s p ro n o u n c e d r e l a t i o n s h i p t o t h e o t h e r members o f Group 2c t h a n d o e s T e l l i n a b u t t o n i . I t c o r r e l a t e s w ith o n l y one s p e c i e s , T e l l i n a b u t t o n i , above t h e 0 .6 0 0 l e v e l . N o t h r i a c o r r e l a t e s w i t h f o u r o t h e r s p e c i e s i n th e g r o u p a t v a l u e s b e tw e e n 0 .6 0 0 and 0 .4 0 0 : G l d t t i d i a a l b i d a ( 0 . 5 1 3 ) , C h a e to z o n e c o ro n a ( 0 . 4 7 3 ) , L u c i n i s c a n u t t a l l i ( 0 .4 3 0 ) , T h a l e n e s s a s p i n o s a ( 0 . 4 2 6 ) , and P a r a p h o x u s f a t i g a n s ( 0 .4 0 8 ) . Four o t h e r s p e c i e s i n t h e g ro u p c o r r e l a t e w i t h N o t h r i a 273 above th e 0 .0 1 l e v e l o f s i g n i f i c a n c e ; th e f o u r r e m a in in g s p e c i e s c o r r e l a t e w i t h , N o t h r i a a t v a l u e s b e lo w t h i s l e v e l . Ten s p e c i e s n o t members o f G roup 2c c o r r e l a t e w i t h T e l l i n a b u t t o n i o r N o t h r i a e l e g a n s o r b o t h , a t or above th e 0 .4 0 0 l e v e l . S p e c i e s i n o t h e r g ro u p s c o n s i d e r e d f o r p o t e n t i a l m em bership i n a g ro u p a r e s e l e c t e d on th e b a s i s o f a h i g h e r r - v a l u e ( 0 . 4 0 0 ) t h a n t h a t u s e d as t h e b a s i s f o r th e i n i t i a l d e f i n i t i o n o f th e g r o u p . The r e a s o n f o r s e l e c t i n g t h i s c u t - o f f p o i n t i s t h a t n e a r l y a l l i n t r a - g r o u p c o r r e l a t i o n s a r e a t o r above t h i s v a l u e . E i g h t o f t h e s e a r e mem b e r s o f o t h e r g r o u p s o f th e seco n d m ain d e n d r i t i c b r a n c h ; two a re members o f Group l c . The t e n s p e c i e s a r e l i s t e d i n T a b le 17. They s h o u ld be c o n s i d e r e d a s p o t e n t i a l f a u n a l e l e m e n t s w ith G roup 2c i n any r e d e f i n i t i o n o f th e N o t h r i a - T e l l i n a a s s o c i a t i o n . Members o f f o u r r e c u r r e n t g r o u p s a r e i n c l u s t e r G roup 2 c . T h ese a r e th e c o m p le te G roups N - Y I I I , N-IX and N -X II and one o f t h e two members o f Group N -X I. T e l l i n a and N o t h r i a , b o t h s h a l l o w w a t e r i n h a b i t a n t s , h av e s u b s t a n t i a l n e g a t i v e c o r r e l a t i o n s w ith t h e " d o m in a n ts " o f th e c l a s s i c a l l y d e f i n e d a s s o c i a t i o n s , A m p h io d ia - C a r d i t a a n d P e c t i n a r i a - C h l o e i a , t h a t p o p u l a t e th e d e e p e r p o r t i o n s o f th e n o r t h e r n s h e l f and s l o p e . T h e se v a l u e s a r e a s f o l lo w s : A m ph io d ia u r t i c a ( - 0 . 4 2 2 , T e l l i n a ; - 0 . 4 2 9 , N o t h r i a ) , C a r d i t a v e n t r i c o s a ( - 0 . 3 5 9 ; - 0 . 3 5 1 ) , P e c t i n a r i a c a l i f o r n i - e n s i s ( - 0 . 3 3 3 ; - 0 .2 9 9 ) and C h l o e i a p i n n a t a ( - 0 . 2 7 9 ; - 0 .2 5 1 ) . 274 T a b le 17. S p e c ie s t h a t C o r r e l a t e w ith T e l l i n a b u t t o n i a n d / o r N o t h r i a e l e g a n s above th e 0 .4 0 0 l e v e l b u t a r e Members o f G roups o th e r th a n Group 2 c . r w i t h r w ith S p e c ie s T e l l i n a N o t h r i a Group G oniada b ru n n e a 0 .5 0 5 0 .4 9 1 2m M o d io lu s s p . 0 .4 2 9 0 .4 8 9 2d T u r b o n i l l a s p . 0 .6 4 3 0 .4 8 1 2e N e p h ty s c a e c o i d e s 0 .4 9 6 0 .4 3 2 lc M ediom astus c a l i f o r n i e n s i s 0 .1 4 6 0 .4 6 9 2h P h y llo d o c e s p . 0 .247 0 .4 6 5 . 2h A m p e lisc a c o m p ressa 0 .2 1 7 0 .4 2 9 2a A m phioplus h e x a c a n th u s 0 .3 1 1 0 .4 0 7 lc nem atode unknown M agelona s a c c u l a t a 0 .4 0 6 0.404 0 .1 7 3 0.343 2h 2d 275 O nly t h e l a s t two v a l u e s a r e b e lo w th e 0 .0 1 s i g n i f i c a n c e l e v e l ( - 0 . 2 9 8 ) . T e l l i n a b u t t o n i a l s o h a s a p ro n o u n c e d n e g a t i v e c o r r e l a t i o n , - 0 . 4 2 7 , w i t h G l y c e r a c a p i t a t a . Two o t h e r g r o u p s , G roups 21 and 2m, on t h i s b r a n c h c o n t a i n i m p o r t a n t s h a l l o w - w a t e r f a u n a l e l e m e n t s . G roup 21 i s com posed o f th e p o l y c h a e t e s P r i o n o s p i o m alm g ren i and H a p l o s c o l o p l o s e l o n g a t u s . The fo rm e r i s th e ’’d o m in a n t” o f th e P r i o n o s p i o a s s o c i a t i o n , and t h e l a t t e r i s an i m p o r t a n t member o f t h i s a s s o c i a t i o n ( B a r n a r d , 1 9 6 3 ) . Group 2m h as as one o f i t s members t h e g a s t r o p o d , O l i v e l l a b a e t i c a ; t h i s s p e c i e s was p r e s e n t i n 45 p e r c e n t o f t h e 100 Van Veen g r a b s a m p le s c o l l e c t e d b e tw e e n 2.1 and 10.1 m e te r s on t h e s h e l f (G. J o n e s , 1 9 6 4 ). G roup 3 a , D i o p a t r a o r n a t a The t h i r d m ain b r a n c h c o n t a i n s n i n e r e l a t i v e l y sm all g r o u p s . The l a r g e s t g r o u p , 3 a , w i t h s e v e n s p e c i e s i n c l u d e s D i o p a t r a o r n a t a ; t h i s p o l y c h a e t e h a s b e e n r e c o g n i z e d a s th e " d o m in a n t” o rg a n is m o f an a s s o c i a t i o n t h a t i s g e n e r a l l y d i s t r i b u t e d i n s h a l l o w w a te r a d j a c e n t t o a r e a s o f kel£> ( B a r n a r d l a ] , i n S t e v e n s o n , 1961; B a r n a r d , 1 9 6 3 ). H artm an ( i n S t e v e n s o n , 1961) com b in es D i o p a t r a w i t h N o t h r i a e l e g a n s t o i d e n t i f y an a s s o c i a t i o n i n n o r t h e r n a r e a s a t s h a ll o w d e p t h s . The r v a lu e o f 0 .3 3 1 s u p p o r t s t h e i d e a o f some ty p e o f r e l a t i o n s h i p b e tw e e n t h e s e two s p e c i e s . G roup 3c c o n t a i n s a s one o f i t s fo u r members t h e p o l y c h a e t e P h e r u s a 276 n e o p a p i l l a t a , w h ic h h a s b e e n s u g g e s t e d a s a ’'d o m in a n t" i n one o f th e m inor a s s o c i a t i o n s . The p o l y c h a e t e P i s t a d i s j u n c t a was d e s c r i b e d a s a " c o - d o m in a n t" w i t h N o t h r i a p a l l i d a i n a d e e p - w a t e r a s s o c i a t i o n ( B a r n a r d , H artm an and J o n e s , 1 9 5 9 ) . Beyond t h e s e few o b s e r v a t i o n s i t i s d i f f i c u l t t o make any m e a n in g f u l i n t e r p r e t a t i o n s o f th e g r o u p s o f t h i s b r a n c h o f t h e d e n d ro g ra m on th e b a s i s o f p r e v i o u s know ledge o f th e s h e l f b i o t a . G roup 4 c , A m ph io d ia u r t i c a ; Group 4 b , C a r d i t a v e n t r i c o s a ; an d Group 4 e , P e c t i n a r i a c a l i f o r n i e n s i s and C h l o e i a p i n n a t a The f o u r t h m ain b r a n c h (B ra n c h F o u r) o f t h e d e n d r o gram i n c l u d e s f o u r g r o u p s t h a t a r e composed o f t h e i m p o r t a n t f a u n a l e l e m e n t s o f th e o u t e r p o r t i o n o f th e n o r t h e r n s h e l f and i t s a d j a c e n t s l o p e . T h e se a r e s p e c i e s t h a t have been c i t e d as p r o m in e n t members o f t h e A m phiodia u r t i c a , A m p h io d ia - C a r d i t a , A m p h io d ia - O nuphis and P e c t i n a r i a - C h l o e i a a s s o c i a t i o n s ( B a r n a r d and Z ie s e n h e n n e , 1961; B a rn a rd and H artm an , 1959; B a r n a r d , H artm an and J o n e s , 1959; J o n e s , 1 9 6 4 ). A p o r t i o n o f th e f o u r t h b r a n c h i s d ia g ra m e d i n F i g u r e 66 . G roups 4 a , 4 b , 4c and 4e a r e i n d i c a t e d . The OTU’s a r e nam ed, and t h o s e t h a t a r e e l e m e n t s o f one o f th e r e c u r r e n t g r o u p s (REGROUP) a r e i d e n t i f i e d b y th e Roman n u m e ra l Figure 66 B ranch Four o f th e N o r t h e r n S h e l f D endrogram . 277 0 .2 2 0 0 0.1(800 0*71(00 1 .0 0 0 0 o » 3 ? o r i ! I OR O U ? hfe I i {R 0D 7 ](• i 1 I I : i i • l.-l ■ i L i ! 1 I • - - L -5 1 - L ------- o ro i d . Figure 66 JH FOURTH M ill BRAHOH ( I n p a r t ) 1 6 I 3D OEOUP l|a • « AHKLXMA H A R C O O K X i i AKPXLISCA H D D U U n. ADOETOBHTXA CYCLIA, A f f . E - I I I 7 3 ALKJSIA RXDOEDOBESIS 6 AHPKJWJA PAOIFICA, H - I I I ho CARDITA TOTRICOSA. A f f . E - I , M-UI _ _ _ 70 nMOQABDIDH OBHSFILOSOK, I - I I I ’< • UEOOOE A 71 id o d la Tgauia, A f f . x - m 7 6 H iniU M R . SQBPUUfUM ! - a im rc u L iD um oroim . A f f . i - i i i ' 1 PAFTHALIS PAOIFIOA ■ ostraood r a n o n , e - i i 4 3 PAHAFHDXUS BICTJaPIDATTJS, A f f . R-XXI AMPHIODIA u r t i c a , * - I 7 6 a x x h o p sid a 3SRRICATA, E - I I'*’ OLTCXHA GAPXXASA, l - I ib OEATHIA OfiRXULAIIPROIS, 1 .1 XODOBEUA a , A f f . X -I 77 PAHATOOXns ROBUaTUS, A f f . I-I ■r p a h a p h d e js s m u t , x - u i M LRPTOSTXAPTA ALBICAES 1 ' - FHOLOl OLAEKA, X -I 9 7 ROOHXFOHTIA ALEUTICA .7 0 AMHHHXPAn AUL00ABTK8 O t! b fa i b o b ? I p 6 AJORLXSCA HACBOCBPHALA XICIPP1 TUKUUL 134 OHLORIA FXHRATA, A f f . E-VI 7 3 DIASTXLHUE UXBCOVX, E -V I 176 PROTIEARIA OALXPORRmaia. I - I 74 AHEH1ALUM PALLIDULUM 6 6 PBOXOORPHALUS HOJOLIfl h h ip p o k d o e m r io v L A in s 6: WtSTHDOSIUA O A X O T T L A 61 AMKUOAmHA AM PHACARTHA 101 WT.T.TW* 41ARKKXRI 16 6 P0T0MASTU8 TKETJIS lfi 163 9 a 278 279 u s e d t o d e s i g n a t e th e g r o u p . Group 4 c , th e l a r g e s t g ro u p on th e f o u r t h main b r a n c h o f th e d e n d ro g ra m , i n c l u d e s A m phiodia u r t i c a , t h e d e s i g n a t e d " d o m in a n t” s p e c i e s o f t h e A m phiodia a s s o c i a t i o n s ( B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). T h i s s p e c i e s i s c o n s i d e r e d " c o - d o m i n a n t " w i t h C a r d i t a v e n t r i c o s a and w i t h O n u p h is n e b u l o s a and i s c o n s i d e r e d " s u b d o m in a n t” i n t h e A m phioplus h e x a c a n t h u s a s s o c i a t i o n ( B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). A m p h io d ia u r t i c a i s t h e m o st w i d e l y d i s t r i b u t e d m a c r o f a u n a l i n v e r t e b r a t e on t h e m a in la n d s h e l f ( B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). A m ph io d ia u r t i c a c o r r e l a t e s a t o r ab o v e t h e 0 .4 0 0 l e v e l w i t h a l l o f th e members o f Group 4c e x c e p t t h e p o l y c h a e t e Ammotrypane a u l o g a s t e r ( s e e T a b le 1 8 ) . Two o f t h e s e s p e c i e s , G l y c e r a c a p i t a t a and A x in o p s id a s e r r i c a t a , h av e b e e n p r e v i o u s l y c o n s i d e r e d a s i m p o r t a n t a s s o c i a t e s o f A m p h io d ia u r t i c a . T h is i m p o r t a n t o p h i u r o i d s p e c i e s c o r r e l a t e s a t 0 .4 0 0 o r above w i t h 10 o t h e r s p e c i e s ( T a b le 1 8 ) ; t h e s e a r e members o f one o f th e f o l l o w i n g g r o u p s : G roup l a , 4b, 4d, 4 e , 4 g , 5d or 4 e . O nly 3 o f t h e t e n a r e members o f g r o u p s on o t h e r b r a n c h e s o f th e d e n d ro g ra m . A m ph io d ia u r t i c a h a s a t o t a l o f 25 o t h e r s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s ( 0 .4 0 0 - 0 . 2 9 8 l e v e l ) among th e 200 s p e c i e s a n a l y z e d . C a r d i t a v e n t r i c o s a , w i t h a c o r r e l a t i o n o f 0 .3 6 4 , i s one o f t h e s e . The r e l a t i v e im p o rta n c e o f a l l o f t h e s e s p e c i e s 280 T a b le 1 8 . A L i s t o f t h e S p e c ie s t h a t C o r r e l a t e w i t h A m phiodia u r t i c a above th e 0 .4 0 0 l e v e l . S p e c ie s C o r r e l a t i o n Group P a ra p h o x u s b i c u s p i d a t u s 0 .7 1 6 4c G ly c e r a c a p i t a t a 0 .7 0 5 4c A x in o p s id a s e r r i c a t a 0 .6 8 8 4c o s t r a c o d unknown 0 .6 4 3 4c P h o lo e g l a b r a 0 .6 3 5 4c P a ra p h o x u s s i m i l i s 0 .6 0 8 4c G n a t h i a c r e n u l a t r i f r o n s 0 .5 6 9 4c R o c h e f o r t i a a l e u t i c a 0 .5 5 9 4c L e p to s y n a p t a a l b i c a n s 0 .5 1 7 4c N em ocirdium c e n t i f i l o s u m 0 .5 1 3 4b A m p h ip h o lis sq u a m a ta 0 .4 9 4 4d A m p e lis c a p a c i f i c a 0 .4 9 8 4b P e c t i n a r i a c a l i f o r n i e n s i s 0 .4 8 5 4e M a n g e lia s p . 0 .4 8 3 5e A m phiura a r c y s t a t a 0 .4 7 5 4d P r o to m e d ia a r t i c u l a t a 0 .4 7 3 5d P a ra p h o x u s r o b u s t u s 0 .4 3 9 4c B y b l i s v e l e r o n i s 0 .4 3 0 ■ 4n C a m p y la s p is C 0 .4 2 1 4g L y s i a n a s s a o c u l a t a 0 .4 1 4 l a E u d o r e l l a A 0 .4 0 3 4 c 281 s h o u ld be a s s e s s e d p r e p a r a t o r y t o th e r e d e f i n i t i o n o f any a s s o c i a t i o n o f w hich A m phiodia i s an i m p o r t a n t member. The n e g a t i v e c o r r e l a t i o n s o f two members o f Group 4 c , A m ph io d ia u r t i c a and G l y c e r a c a p i t a t a w i t h T e l l i n a b u t t o n i and N o t h r i a e l e g a n s (G roup 4 b ) , h av e b e e n n o te d p r e v i o u s l y . An a d d i t i o n a l r e l a t i o n s h i p b e tw e e n members o f t h e s e two g r o u p s i s t h e - 0 .3 5 7 c o r r e l a t i o n b e tw e e n A m phiodia u r t i c a and C h a e to z o n e c o r o n a . Members o f 3 r e c u r r e n t g r o u p s fro m th e REGROUP a n a l y s i s o f t h i s sam ple s e t a r e members o f G roup 4 c . A m phiodia u r t i c a and 6 o t h e r members and a s s o c i a t e s o f Group N -I a re members o f G roup 4 c. T h i s i s a n o t h e r d e m o n s t r a t i o n o f some c o r r e s p o n d e n c e b etw een th e two m e th o d s. One o f t h e 5 mem b e r s o f G roups N - I I , t h e f a u n a l e le m e n t ” o s t r a c o d u n k n o w n ,” i s a member o f Group 4 c . A member o f G roup N - I I I and a s p e c i e s a s s o c i a t e d o n l y t o t h i s g r o u p a r e a l s o m em bers o f G ro u p 4c. Group 4c w i t h 4d ( a s m a l l g ro u p n o t d e f i n e d i n F i g u r e 66 ) i s c o n n e c te d t o th e b r a n c h t h a t i n c l u d e s G roups 4 a and 4 b . C a r d i t a v e n t r i c o s a i s a member o f Group 4 b ; i t s r e l a t i o n s h i p t o A m p h io d ia u r t i c a h a s b e e n d i s c u s s e d (B a r n a rd and Z ie s e n h e n n e , 1961; G. J o n e s , 1 9 6 4 ). The s i g n i f i c a n t c o r r e l a t i o n o f t h e s e two s p e c i e s h a s b e e n n o t e d . C a r d i t a v e n t r i c o s a h a s r e l a t i v e l y h ig h c o r r e l a t i o n s w ith two o t h e r m em bers o f G roup 4 c, G n a t h i a c r e n u l a t i f r o n s ( 0 .5 4 6 ) and A x i n o p s id a s e r r i c a t a ( 0 . 5 3 4 ) . A m p h io d ia u r t i c a , i t s h o u ld 282 be r e c a l l e d ( T a b l e 1 8 ) , c o r r e l a t e s w ith two 4b s p e c i e s above th e 0 .4 0 0 l e v e l : N em ocardium c e n t i f i l o s u m ( 0 .5 1 3 ) and A m p e lis c a p a c i f i c a CO.4 9 8 ) . O th e r h i g h i n t e r - g r o u p c o r r e l a t i o n s e x i s t and a r e r e v e a l e d by a b s t r a c t i n g fro m th e o r i g i n a l m a t r i x a l l o f t h e 104 c r o s s - c o r r e l a t i o n s b e tw e e n t h e s p e c i e s o f t h e s e two g r o u p s . T h e re a r e 51 s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s b e tw e e n s p e c i e s o f t h e two g r o u p s ; 19 o f t h e s e e x c e e d th e 0 .4 0 0 l e v e l . The r e m a in in g 53 c o m b in a t i o n s y i e l d 48 i n s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s and 5 i n s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n s . T/tfhile su ch an e f f o r t i s r e a s o n a b l e when e x a m in in g th e r e l a t i o n s h i p b e tw e e n j u s t two g r o u p s , i t becomes q u i t e b u rd en so m e a s a g e n e r a l p r o c e d u r e when c o n s i d e r i n g th e i n t e r a c t i o n s b e tw e e n a l l th e m u l t i - s p e c i f i c g ro u p s i n th e d e n d ro g ra m . I t i s r e a s o n a b l e t o i n t e r p r e t Group 4b i n te r m s o f C a r d i t a v e n t r i c o s a , i t s b e s t known member. C a r d i t a h a s h i g h p o s i t i v e c o r r e l a t i o n s w ith f o u r o t h e r members o f t h i s g r o u p : A m p e lis c a p a c i f i c a ( 0 . 7 2 4 ) , B i t t i u m s u b p la n a tu m ( 0 . 6 5 9 ) , N em ocardium c e n t i f i l o s u m ( 0 .6 3 6 ) and ,fs i p u n c u l i d unknown" ( 0 . 5 0 5 ) . C a r d i t a c o r r e l a t e s w i t h o n ly one member o f th e g r o u p , P a n t h a l i s p a c i f i c a , belo w t h e 0 .4 0 0 l e v e l , b u t th e v a lu e o f t h e i r c o r r e l a t i o n , 0 .3 8 7 , e x c e e d s t h e 0 .0 1 l e v e l o f s i g n i f i c a n c e . B e s i d e s th e members o f i t s own g r o u p , 4b, and Group 4c C a r d i t a c o r r e l a t e s above th e 0 .4 0 0 l e v e l w i t h a few s p e c i e s t h a t a r e members o f o t h e r g r o u p s : 4 a , A d o n to r h in a 283 c y c l i a ( 0 .5 3 9 ) and A m p e lis c a h a n c o c k i ( 0 . 4 9 9 ) ; 4 e , P e c t i n a r - i a c a l i f o r n i e n s i s ( 0 . 4 7 4 ) ; 4 i , D exam onica r e d u n c a n s ( 0 . 5 6 2 ) ; 4n, B y b l i s v e l e r o n i s ( 0 .4 5 8 ) and 5 a , N u c u la n a t a p h r i a ( 0 . 4 3 6 ) . I t c o r r e l a t e s w i t h C h l o e i a p i n n a t a a t t h e 0 .3 3 7 l e v e l . C a r d i t a v e n t r i c o s a h a s s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n s w i t h t h r e e s p e c i e s t h a t a l s o d e m o n s t r a t e s u b s t a n t i a l n e g a t i v e c o r r e l a t i o n s w i t h A m p h io d ia u r t i c a : T e l l i n a b u t t o n i ( - 0 . 3 5 9 ) , N o t h r i a e l e g a n s ( - 0 . 3 5 1 ) and C h a e to z o n e c o ro n a ( - 0 . 3 2 9 ) . Members o f two r e c u r r e n t g r o u p s fro m th e REGROUP a n a l y s i s o f t h i s sam p le s e t a r e m embers o f Group 4 b . T h ese a r e p r i m a r i l y G ro u p N - I I I members (2 s p e c i e s ) and fo rm s a f f i l i a t e d w ith t h a t g ro u p (3 s p e c i e s ) . F i f t e e n o f t h e 21 s p e c i e s o f Groups 4b and 4c a r e e i t h e r members o f G roup N -I or N - I I I or a r e a s s o c i a t e d w ith one or b o th o f t h e s e r e c u r r e n t g r o u p s . Group 4 a j o i n s to Group 4b a t a v a l u e o n ly s l i g h t l y below t h e a r b i t r a r y 0 .3 5 0 l e v e l s e l e c t e d to d e f i n e t h e g ro u p s o f t h e d e n d ro g ra m . The c l o s e a f f i l i a t i o n o f t h e s p e c i e s o f t h e s e two g r o u p s i s i n d i c a t e d . As n o t e d , two o f i t s m em bers, A d o n t o r h in a c y c l i a and A m p e lis c a h a n c o c k i , c o r r e l a t e w ith C a r d i t a v e n t r i c o s a above t h e 0 .4 0 0 l e v e l . Both o f i t s p e le c y p o d m em bers, A d o n t o r h in a c y c l i a and A l i g e n a r e d o n d o e n s i s , a r e c o n s i d e r e d i m p o r t a n t m o llu s c a n e l e m e n t s o f t h e A m p h io d ia - C a r d i t a a s s o c i a t i o n (G. J o n e s , 1 9 6 4 ). 284 The f o u r t h g r o u p , 4 e , i l l u s t r a t e d i n F i g u r e 66 i n c l u d e s a number o f s p e c i e s c o n s i d e r e d i m p o r t a n t e l e m e n t s o f th e o u t e r s h e l f and s l o p e f a u n a . The p o l y c h a e t e s P e c t i n a r i a c a l i f o r n i e n s i s and C h l o e i a p i n n a t a have b e e n u s e d t o d e f i n e one a s s o c i a t i o n r e s t r i c t e d t o t h i s h a b i t a t . The o p h i u r o i d A m p h ia c a n th a a m p h a c a n th a h a s b een r e c o g n i z e d as t h e "d o m i- n a n t " o f a m in o r s lo p e a s s o c i a t i o n . The n e s t - b u i l d i n g p e le c y p o d Amygdalum p a l l i d u l u m i s c o n s i d e r e d th e " d o m in a n t” o f a n o t h e r d e e p - w a t e r m in o r a s s o c i a t i o n ( B a r n a r d , H artm an and J o n e s , 1959; B a rn a rd [ a ] , i n S t e v e n s o n , 1961; G. J o n e s , 1964; and i n AHF:USC, 1 9 6 5 ) . The p e le c y p o d T e l l i n a c a r p e n t e r i i s m e n tio n e d a s a f a u n a l e le m e n t o f t h e o u t e r s h e l f and s lo p e a s s o c i a t i o n s (G. J o n e s , 1 9 6 4 ). F or t h e s e r e a s o n s Group 4e a p p e a r s t o be a r e a s o n a b l e a s s e m b la g e o f s p e c i e s . The c o r r e l a t i o n v a l u e b e tw e e n P e c t i n a r i a and C h l o e i a i s 0 .4 7 3 . Each o f t h e s e s p e c i e s h a s a number o f i n t r a - g r o u p c o r r e l a t i o n s o v e r th e 0 .4 0 0 l e v e l ; m ost of t h e s e h ig h c o r r e l a t i o n s a r e c o n f i n e d t o t h e u p p e r b r a n c h i n Group 4e ( s e e F i g u r e 66) . T h e se s p e c i e s a r e D i a s t y l i d a e unknown ( 0 .6 1 1 , P e c t i n a r i a ; 0 .6 3 6 , C h l o e i a ) , N ic ip p e tu m id a ( 0 .5 6 3 , P e c t i n a r i a ; 0 .6 3 6 , C h l o e i a ) , A m p e lis c a m a c r o c e p h a la v. ***» ( 0 . 5 0 7 , P e c t i n a r i a ; 0 .6 7 5 , C h l o e i a ) , P h o x o c e p h a lu s h o m i l i s ( 0 . 3 1 6 , P e c t i n a r i a ; 0 .5 7 6 , C h l o e i a ) , and Amygdalum p a l l i d u l u m ( 0 . 3 8 3 , P e c t i n a r i a ; 0 . 5 2 4 , C h l o e i a ) . From t h e c o n f i g u r a t i o n o f t h e b r a n c h e s w i t h i n G roup 285 4e ( s e e F i g u r e 66) , i t i s a p p a r e n t t h a t t h i s g ro u p c o u ld be r e a s o n a b l y s u b d i v i d e d i n t o two u n i t s : t h e u p p e r g r o u p , A m p e lis c a m a c r o c e p h a la to P h o x o c e p h a lu s h o m i l i s , w ould c o n t a i n P e c t i n a r i a , C h l o e i a and Amygdalum; th e low er group* Hippomedon d e n t i c u l a t u s t o N o to m a stu s t e n u i s , i n c l u d e s A m p h ia c a n th a a m p h a c a n th a . Where th e y h av e b e e n e x a m in e d , t h e c o r r e l a t i o n s b e tw e e n th e members o f t h e s e two b r a n c h e s ( " u n i t s " ) a r e r e a s o n a b l y h i g h . Exam ples a r e as f o l l o w s : P e c t i n a r i a w i t h A m p h ia c a n th a a m p h a c a n th a , 0 .3 0 7 ; P e c t i n a r i a w i t h T e l l i n a c a r p e n t e r i , 0 .4 4 3 ; C h l o e i a w i t h A m p h ia c a n th a , 0 . 3 2 2 ; and C h l o e i a w i t h T e l l i n a c a r p e n t e r i , 0 .4 2 0 . A l l o f t h e e x t r a - g r o u p c o r r e l a t i o n s o f P e c t i n a r i a and C h l o e i a o v e r 0 .4 0 0 a re w i t h s p e c i e s i n o t h e r g ro u p s on B ra n c h F o u r . T h e re a r e 16 o f t h e s e f o r th e two s p e c i e s ; e l e v e n , o r 69 p e r c e n t , a r e w i t h s p e c i e s o f G ro u p s 4 a , 4b and 4 c . Only t h r e e members o f Group 4e a p p e a r e d i n t h e g r o u p in g r e s u l t s o f t h e r e c u r r e n t g ro u p a n a l y s i s o f t h i s s a m p le s e t . One member o f G roup N-IV ( D i a s t y l i d a e unknown) and one s p e c i e s show ing a f f i n i t y to G roup N-IV ( C h l o e i a p i n n a t a ) and one member o f G roup N-I ( P e c t i n a r i a c a l i f o r n i - e n s i s ) a re members o f Group 4 e . G roup 5 f , L i s t r i o l o b u s p e l o d e s The f i f t h m ain b r a n c h o f th e d e n d ro g ra m (B ra n c h F i v e ) i n c l u d e s two m a jo r g r o u p s composed o f a number o f 286 p r o m in e n t f a u n a l e le m e n ts o f t h e n o r t h e r n s h e l f a t i n t e r m e d ia te d e p t h s ; L i s t r i o l o b u s p e l o d e s i s one o f t h e s e . T h is e c h i u r o i d worm h a s been d e s i g n a t e d a s th e M d o m in a n tM o f th e e x t e n s i v e m u d -d w e llin g a s s o c i a t i o n o f t h i s r e g i o n (B a r n a rd and H artm an , 1959; B a r n a r d , H artm an and J o n e s , 1959; G. J o n e s , 1 9 6 4 ). T h is b r a n c h o f th e d e n d ro g ra m i s diagram m ed i n F i g u r e 67. G roup 5a and 5 f a r e i n d i c a t e d . The OTU’ s a r e nam ed, and t h o s e t h a t a r e e le m e n ts o f one o f th e r e c u r r e n t g ro u p s (REGROUP) a r e i d e n t i f i e d b y t h e Roman n u m e ra l u s e d to d e s i g n a t e th e g r o u p . G roups 5a and 5 f may be i n t e r p r e t e d i n te r m s o f L i s t r i o l o b u s p e l o d e s . L i s t r i o l o b u s h a s f i v e s i g n i f i c a n t i n t r a - g r o u p c o r r e l a t i o n s : S a x i c a v e l l a p a c i f i c a ( 0 . 6 9 4 ) , T e r e b e l l i d e s s tr o e m i ( 0 . 4 6 1 ) , H e te ro p h o x u s o c u l a t u s ( 0 . 4 5 7 ) , p h o r o n id s unknown ( 0 .4 0 4 ) and C e r a t o c e p h a l a £ . a m e r ic a n a ( 0 . 3 8 2 ) . Of t h e e i g h t s p e c i e s t h a t c o r r e l a t e w ith L i s t r i o l o b u s , s i x a r e members o f g r o u p s o f t h e 5 th d e n d r i t i c b r a n c h . F our a r e Group 5a m em bers; t h e s e a r e L i s t r i e l l a g o l e t a ( 0 . 4 8 3 ) , P o e c i l o c h a e t o u s j o h n s o n i ( 0 . 4 5 3 ) , P e r ip lo m a d i s c u s ( 0 .3 4 0 ) and ire n t e r o p n e u s t unknown” ( 0 . 3 1 4 ) . O ne, V o l v u l l e l a s p . ( 0 . 3 6 0 ) , i s a member o f Group 5d; a n o t h e r , R o c h e f o r t i a s p . ( 0 . 2 9 8 ) , i s a member o f G roup 5 e . Two a r e members o f Group 3 f : G l y c e r a a m e r ic a n a ( 0 .4 2 1 ) and A s y c h is d i s p a r i d e n t a t a ( 0 . 3 1 1 ) . T h r e e a d d i t i o n a l s p e c i e s , Group 5a m em bers, a r e c o n s id e r e d i m p o r t a n t f a u n a l a s s o c i a t e s o f L i s t r i o l o b u s ; t h e s e a r e Compsomyax s u b d i a p h a n a , N u c u la n a t a p h r i a and Figure 67 B ran ch F iv e o f th e N o r t h e r n S h e l f D endrogram - 287 0.2200 0 . 1 ( 8 0 0 0 .7 1 (0 0 1.0000 010 XD. 288 Figure 67 FIFTH M A . X K B H A H C H G R O U P f>a : • i- « i l 7 m r j.T iitg a t OALIFOHMBHSIS 7 ■ , LISTBIBU a. Q0LB1A : K H T K R O P W B U S T A OFKHOWJ, H -V H 1 AHCX8TR0Sm.Ia T K H T A C T JL A T A - ? COMPSOMSAI 3UBDIAPHAHA, A f f . ■-x, >-n abHACOM A T0LDZF0BNL3 - PKRIPLOHA DISCOS ': POSCZLOCHAKTUS JO HVSONX H U C O L A H A TAPHRIA, S .V H M A C B L O H A PACIFICA • - I - . - 4- O B O u p Sr ■ J b 3 o HBTKROPHOXUS 0 G 0 L A T 0 3 . V-X : l - PBOROHXDS O n H O W I l o I X R O B OBMHA -') SAXICAVBLLA PACIFICA 111 U STRIOLOBOS PBLODBS 1 3 7 C B R A TO C EPH A LA C . A M E R IO A H A i 7 t TBRKBELLIDBS STROKE, ■ -! :s7 i : b >?;• II-'. 289 C a l l i a n a s s a s p . ( B a r n a r d and H artm a n , 1959; J o n e s , 1 9 6 4 ), A n o th e r i n t e r e s t i n g f a c t a b o u t L i s t r i o l o b u s p e l o d e s i s t h a t i t f a i l s t o c o r r e l a t e s i g n i f i c a n t l y w i t h a l l o f t h e o t h e r d e s i g n a t e d " d o m i n a n t s ” o f th e n o r t h e r n p o r t i o n o f t h e s h e l f . T hese v a l u e s a r e as f o l l o w s : - 0 . 0 5 6 , A m phiodia u r t i c a ; - 0 . 0 5 5 , C a r d i t a v e n t r i c o s a ; 0 . 0 6 1 , P e c t i n a r i a c a l i f o r n i e n s i s ; - 0 . 1 0 9 , C h l o e i a p i n n a t a ; - 0 . 1 4 3 , T e l l i n a b u t t o n i ; and - 0 . 0 8 9 , N o t h r i a e l e g a n s . O nly a few s p e c i e s o f G roups 5a and 5 f a r e members o f t h e r e c u r r e n t g r o u p s (REGROUP) d e r i v e d fro m t h i s sam ple s e t . B o th members o f G roup N -V II a r e members o f G roup 5 a; Compsomyax s u b d i a p h a n a , a G roup 5a member, was a l s o a s s o c i a t e d w i t h G roups N -I and N - I I . Two members o f Group 5 f a r e members o f r e c u r r e n t Group N - I . I n t e r - g r o u p C o m p a riso n s Some o f th e m a jo r g r o u p s o f t h e N o r t h e r n S h e l f d e n d ro g ra m a r e com pared i n T a b le 19. The d e g r e e o f r e l a t e d n e s s b e tw e e n them i s su m m a riz e d . E ach row o f t h e t a b l e i s d e r i v e d from an r - m a t r i x . F or i n t e r - g r o u p c o m p a ris o n s t h i s m a t r i x i s a r e c t a n g u l a r m a t r i x c o n s i s t i n g o f t h e r - v a l u e s y i e l d e d by a l l p o s s i b l e s p e c i e s - p a i r c o m b in a tio n s o f th e members o f t h e two g r o u p s . The s i n g l e i n t r a - g r o u p c o m p a r i son sum m arized i n t h e t a b l e i s b a s e d on th e t r i a n g l e r - m a t r i x o f a l l p o s s i b l e c o m b in a tio n s o f th e s p e c i e s o f t h a t g r o u p . For e a c h m a t r i x t h e r - v a l u e s w ere t o t a l e d w i t h i n 290 T a b le 19. A Summary o f th e D eg ree o f C o r r e l a t i o n B etw een Some o f th e Groups o f th e N o r th e r n S h e lf D e n d ro gram . (The v a l u e s i n e a c h c a t e g o r y a r e th e p e r c e n ta g e o f th e t o t a l number o f i n t e r - g r o u p com b i n a t i o n s o f s p e c i e s p a i r s w i t h r v a l u e s w i t h i n th e l i m i t s d e f i n i n g t h a t c a t e g o r y ) . GROUP 2 c , N o t h r ia e l e g a n s - - T e l l i n a b u t t o n i (1 5 ) +1.00 + 0 .4 0 + 0 .2 9 8 0 .0 - 0 .2 9 8 - 0 .4 0 - 1 .0 0 GROUP 4 a (4) A dontorhina, A lig e n a 0.0 0.0 0.0 9 8 .4 1.6 0.0 GROUP 4b ( 8) C a r d i t a 0.0 0.0 0.0 9 0 .0 10.0 0.0 GROUP 4 c (1 3 ) Am phiodia 0.0 0.6 9 .3 7 5 .2 12.1 2.8 GROUP 4 e (1 2 ) P e c t i n a r i a , C h l o e i a , Amygdalum, A m phiacantha 0.0 0.0 1 3 .9 7 8 .3 7 .2 0.6 GROUP 5 f (7) L i s t r i o lo b u s 0.0 0.0 1.0 89 . 5 9 .5 0.0 GROUP 4 c , A m phiodla u r t i c a (1 3 ) GROUP 4 a (4) A d o n to r h in a , 1 7 .4 2 6 .9 5 5 .7 o • o o • o o • o A lig e n a ■ GROUP 4b ( 8) P e c t i n a r i a , C h lo e ia , 18. 3 3 0 .8 4 6 .1 00 • o ■ o o • o Amygdalum, A m phiacantha 291 Table 19 (Cont.) GROUP 4 c , A m p h io d ja u r t i c a ( 1 3 ) , c o n t i n u e d + 1 .0 0 + 0 .4 0 + 0 .2 9 8 0 .0 - 0 . 2 9 8 - 0 .4 0 - 1 .0 0 GROUP 5 f (7 ) L i s t r i o l o b u s 2.2 3 . 3 5 1 .6 4 2 .9 0 .Q 0.0 GROUP 4c A m phiodia ( I n t r a - g r o u p (C o m p a riso n ) 6 9 .3 1 7 .9 1 1 .5 1 .3 0.0 0.0 GROUP 5 f , L i s t r i o l o b u s p e l o d e s (7 ) GROUP 5 a L i s t r i e l l a , Compsomyax, P e r ip lo m a , P o e c i l o - c h a e t u s , N u c u la n a 1 1 .3 1 4 .3 5 3 .0 2 1 .4 0.0 0.0 P e a r s o n ’ s P r o d u c t Moment C o r r e l a t i o n V a lu e s ( r ) 292 th e c a t e g o r i e s fo rm ed by th e l i m i t s C l . 0 0 , + 0 .4 0 0 , + 0 .2 9 8 , 0 . 0 , - 0 . 2 9 8 , - 0 . 4 0 0 , and - 1 . 0 0 ) shown i n th e t a b l e . Each o f t h e s e t o t a l s i s e x p r e s s e d a s th e p e r c e n t a g e i t fo rm s o f t h e t o t a l number o f r ’ s c o n t a i n e d i n i t s p a r t i c u l a r m a t r i x . I n th e f i r s t s e c t i o n o f th e t a b l e Group 2c ( N o t h r i a - T e l l i n a ) i s com pared w i t h f o u r g ro u p s fro m th e f o u r t h d e n d r i t i c b r a n c h , G ro u p s 4 a , 4 b , 4c and 4 e , and one g ro u p o f th e f i f t h d e n d r i t i c b r a n c h , 5 f . As m ig h t be e x p e c t e d fro m th e e x a m i n a t i o n o f th e d e n d ro g ra m ( F i g u r e s 65, 66 , 67) and from t h e p r e c e d i n g d i s c u s s i o n t h e m a j o r i t y o f th e r e v a l u e s r e s u l t i n g from t h e s e c o m p a ris o n s a r e n e g a t i v e . M ost o f them a r e i n s i g n i f i c a n t ( 0.01 l e v e l ) , b u t a number o f s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n s ( 0 .2 9 8 - 0 . 4 0 0 ) and a few more h i g h l y s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n s ( g r e a t e r th a n 0 .4 0 0 ) o c c u r . S p e c i e s o f G roups 4 c , 4e and 5 f h a v e a few i n s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s w i t h members o f Group 2 c . I n o n ly th e s i n g l e i n s t a n c e o f a s p e c i e s t h a t i s a member o f G roup 4c i s t h e r e a s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n w i t h a Group 2c s p e c i e s . The seco n d s e c t i o n o f T a b le 19 i s d e v o te d t o t h e r e s u l t s o f t h e c o m p a ris o n o f G roup 4c w i t h G roups 4 a , 4b and 5 f and to an i n t r a - g r o u p c o m p a ris o n o f t h e s p e c i e s o f G roup 4 c . The l a t t e r p r o d u c e d a t r i a n g u l a r m a t r i x c o n t a i n in g 78 r - v a l u e s . The r e s u l t s o f t h i s a n a l y s i s w i t h i n a g ro u p a r e i n c l u d e d f o r c o m p a r a tiv e p u r p o s e s . The r e s u l t s i n th e s e c o n d s e c t i o n a r e q u i t e 293 d i f f e r e n t th a n t h o s e i n t h e f i r s t s e c t i o n . P o s i t i v e c o r r e l a t i o n s p r e d o m in a te i n th e second s e c t i o n . B o th G roups 4a , and 4b h a v e a f a i r l y h igh p e r c e n t a g e o f s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s and of p o s i t i v e c o r r e l a t i o n s t h a t e x c e e d 0 .4 0 0 . N e g a tiv e c o r r e l a t i o n s o ccu r o n ly i n t h e Group 4b by Group 4c c o m p a r is o n ; th e s e a r e i n s i g n i f i c a n t a t th e 0 . 0 1 l e v e l and a c c o u n t f o r o n ly 4 . 8 p e r c e n t o f t h e t o t a l re v a lu e s o f t h i s m a t c h . No c o m p a r is o n was made b e tw e e n Groups 4 c and 4 e ; b u t i t i s a n t i c i p a t e d t h a t t h e s e r e s u l t s would be s i m i l a r t o the G ro u p 4a by 4 c and 4b by 4c c o m p ar i s o n s . T h e c o m p a riso n b e tw e e n G roups 4c and 5 f was m arked by a h i g h p e r c e n t a g e ( 9 4 .5 p e r c e n t ) o f i n s i g n i f i c a n t c o r r e l a t i o n s ( 0 .0 1 l e v e l ) . T h e r e w ere o n ly f i v e s i g n i f i c a n t c o r r e l a t i o n s , a l l p o s i t i v e ; o n ly two e x c e e d e d + 0 .4 0 0 . A s e x p e c t e d th e i n t r a - g r o u p c o r r e l a t i o n s b e tw e e n th e s p e c i e s of G ro u p 4c w e re p r e d o m in a n tly p o s i t i v e ; 6 9 .3 p e r c e n t o f th e r - v a l u e s a r e p o s i t i v e and e x c e e d + 0 .4 0 0 ; 5 per c e n t were ab o v e 0 . 7 0 0 . An a d d i t i o n a l 1 7 .9 p e r c e n t of t h e r - v a l u e s w e r e p o s i t i v e and s i g n i f i c a n t a t th e 0.01 l e v e l . Q u i t e o b v i o u s l y t h e g e n e r a l l e v e l o f c o r r e l a t i o n w i t h i n a g ro u p i s f a r h i g h e r th a n t h a t b e tw e e n a d j a c e n t gro u p s e v e n when t h e y a re a p p a r e n t l y c l o s e l y r e l a t e d . T h e l a s t s e c t i o n o f th e t a b l e co m p ares G roups 5 f and 5 a. The r e s u l t s are a s e x p e c te d fro m p r e v i o u s c o m p a r i sons o f g r o u p s w i t h i n th e same d e n d r i t i c b r a n c h . 294 The NTSYS C l u s t e r A n a l y s i s o f t h e S o u t h e r n S h e l f S p e c i e s The s o u t h e r n p o r t i o n o f t h e m a in la n d s h e l f , A re a s I V - V I I , i s a v e r y h e t e r o g e n o u s r e g i o n . B o tto m s e d im e n ts a r e d i v e r s e ( F i g u r e s 2 , 3, and 4 ) . For t h i s r e a s o n i t m ig h t be e x p e c t e d t h a t t h i s t e c h n i q u e a p p l i e d t o d a t a b a s e d on a sam ple s e t from t h i s r e g i o n would y i e l d l e s s t h a n s a t i s f a c t o r y r e s u l t s . The a n a l y s i s was made o f th e t o p 150 s p e c i e s , a s r a n k e d by f r e q u e n c y i n th e 1 7 6 -sa m p le s e t , c o l l e c t e d i n 102 s a m p le s fro m t h e s o u t h e r n p o r t i o n o f th e m a in la n d s h e l f . The m a t r i x s i z e was s m a l l eno u g h to p e r m it a c o p h e n e t i c c o m p a ris o n (MXCOMP) o f t h e o r i g i n a l r - m a t r i x and t h e m a t r i x o f c o p h e n e t i c v a l u e s d e r i v e d fro m th e d e n d ro g ra m ( S o k a l and S n e a t h , 1 9 6 3 ) . T h is c o m p a ris o n y i e l d e d a c o r r e l a t i o n v a l u e o f 0 .6 0 8 t h a t i s b e lo w th e d e s i r a b l e minimum l e v e l o f 0 .8 0 0 . T h is i n d i c a t e s t h a t i n th e c l u s t e r i n g p r o c e s s a l a r g e amount o f d i s t o r t i o n was i n t r o d u c e d by t h e g r o u p in g o f some s p e c i e s . G e n e r a l l y th e s p e c i e s o f t h i s d e n d ro g ra m w ere f r a g m ented i n t o s m a l l g r o u p s t h a t a r e d i f f i c u l t t o i n t e r p r e t . T h i r t y - f i v e s p e c i e s w e re n o t i n c l u d e d i n any o f t h e g ro u p s when th e l i n e d e l i m i t i n g th e g r o u p s was draw n a t r = 0 .3 5 0 . G roups form ed o f o n ly two s p e c i e s (17 o f them ) a c c o u n te d f o r an a d d i t i o n a l 34 s p e c i e s . T h e re w ere e i g h t g r o u p s com p o se d o f t h r e e s p e c i e s m em bers. S i x t y - t w o p e r c e n t o f th e 150 s p e c i e s ( o r 93 s p e c i e s ) o f t h i s d e n d ro g ra m w ere members 295 o f su c h s m a l l g ro u p s or l a c k e d g ro u p m em b ersh ip a l t o g e t h e r . The d e n d ro g ra m c o u ld b e d i v i d e d i n t o t h r e e m a jo r p a r t s or b r a n c h e s . The f i r s t m ain b r a n c h i n c l u d e s 58 s p e c i e s ; t h e s e w ere d i v i d e d i n t o 14 g ro u p s by a l i n e drawn a t an r - v a l u e o f 0 .3 5 0 . G roup Id i n c l u d e d A m phioplus h e x a c a n t h u s , d e s i g n a t e d as " d o m in a n t” o rg a n is m o f an im p o r t a n t b e n t h i c a s s o c i a t i o n on t h e San P e d ro Bay s h e l f ( B a r n a r d and Z i e s e n h e n n e , 1 9 6 1 ). G roup Id i n c l u d e s f o u r s p e c i e s i n a d d i t i o n t o A m p h io p lu s h e x a c a n t h u s . These a r e G l o t t i d i a a l b i d a , N u c u la n a t a p h r i a , P r i o n o s p i o p i n n a t a , and A n c i s t r o s y l l i s t e n t a c u l a t a . The c l o s e r e l a t i o n s h i p o f G l o t t i d i a a l b i d a and A m p h io p lu s h a s b e e n docum ented p r e v i o u s l y by J o n e s and B a r n a r d ( 1 9 6 3 ) . A m p h ioplus h e x a c a n th u s a l s o h a s s u b s t a n t i a l l y h i g h c o r r e l a t i o n ( 0 .4 0 0 ) w i t h two o t h e r s p e c i e s : Group l b , C y l i c h n e l l a a t t o n s a ( 0 .4 8 1 ) and G roup l e , S t h e n e l a n e 1 1 a u n i f o r m i s . A m p h io p lu s h a s no n e g a t i v e c o r r e l a t i o n s o v e r t h e - 0 .4 0 0 l e v e l . I t i s i n t e r e s t i n g t o n o t e , h o w e v e r, t h a t i t s c o r r e l a t i o n w i t h A m phiodia u r t i c a i s - 0 . 021 . The s e c o n d m a jo r b r a n c h i n c l u d e d 37 s p e c i e s and 9 g r o u p s . One o f t h e s e g r o u p s c o n t a i n e d N o t h r i a e l e g a n s and T e l l i n a b u t t o n i and a n o t h e r i n c l u d e d D i o p a t r a o r n a t a ; b o th o f t h e s e g ro u p s w ere composed o f o n ly f o u r s p e c i e s . The t h i r d main b r a n c h i n c l u d e d 55 s p e c i e s and 9 g r o u p s . Group 3c c o n t a i n e d A m phiodia u r t i c a ; t h i s i s t h e o n ly l a r g e g ro u p o f t h e d e n d ro g ra m ; i t i n c l u d e s 18 s p e c i e s . The members o f 296 Group 3c a r e l i s t e d i n T a b le 20; t h e i r p ro d u c t-m o m e n t c o r r e l a t i o n v a l u e s w ith A m p h io d ia u r t i c a a r e i n c l u d e d . T h re e e x t r a - g r o u p s p e c i e s c o r r e l a t e w i t h A m p h io d ia u r t i c a above t h e 0 .4 0 0 l e v e l ; Group l b , T e r e b e l l i d e s s t r o e m i ( 0 . 5 1 9 ) and Compsomyax s u b d ia p h a n a ( 0 .4 1 8 ) and Group I n , A m p h ip h o lis s q u a m a ta ( 0 . 4 2 7 ) . T h e se s p e c i e s p l u s t h o s e l i s t e d i n T a b le 20 s h o u ld a l l be c o n s i d e r e d i n any r e d e f i n i t i o n o f t h e A m p h io d ia u r t i c a a s s o c i a t i o n . Summary D i s c u s s i o n The R e c u r r e n t Group M ethod was a p p l i e d to d a t a fro m t h e 1 7 6 -sa m p le s e t an d two sa m p le s u b s e t s : th e N o r t h e r n s h e l f , w i t h 74 s a m p le s ; and t h e S a n ta B a r b a r a s h e l f (A re a I I ) , w i t h 41 s a m p le s . I n e a c h a n a l y s i s t h e s p e c i e s s e l e c t ed w ere t h e to p 200 s p e c i e s , ra n k e d by f r e q u e n c y o f o c c u r r e n c e , i n t h e 1 7 6 -sa m p le s e t . The In d e x o f A f f i n i t y c u t o f f p o i n t was s e t a t 0 .6 5 0 . Each a n a l y s i s i d e n t i f i e d a s i n g l e l a r g e g ro u p ( e n t i r e s h e l f , Group I , 10 s p e c i e s ; N o r t h e r n s h e l f , Group N - I , 13 s p e c i e s ; S a n t a B a r b a r a a r e a , G roup S B - I , 10 s p e c i e s ) , s e v e r a l s m a l l e r g r o u p s o f t h r e e to s i x s p e c i e s , and a num ber o f g r o u p s w ith o n l y two s p e c i e s . A d d i t i o n a l s p e c i e s w ere r e c o g n i z e d a s h a v in g a f f i n i t i e s w i t h some, b u t n o t a l l , o f t h e members o f one or more g r o u p s . The number o f t h e s e s p e c i e s a s s o c i a t e d w i t h a p a r t i c u l a r g ro u p was h ig h f o r th e f i r s t g ro u p form ed ( I , N -I and S B -I) b u t d e c r e a s e d p r o g r e s s i v e l y f o r th e g ro u p s f 297 Table 20. Group 3c D e riv e d b y th e NTSYS r - M a t r i x C l u s t e r i n g A n a l y s i s o f th e S o u th e r n S h e l f . S p e c i e s A m ph io d ia u r t i c a C o r r e l a t e s w i t h A m phiodia u r t i c a A m p e lis c a p a c i f i c a N i c ip p e t u b i d a P a ra p h o x u s s i m i l i s H e te r o p h o x u s o c u l a t u s G l y c e r a c a p i t a t a P a ra p h o x u s b i c u s p i d a t u s ( P o s i t i o n o f A m phiodia u r t i c a i n D endrogram ) P h o lo e g l a b r a P e c t i n a r i a - c a l i f o r n i e n s i s A m p e lis c a p u g e t i c a L e p t o s y n a p t a a l b i c a n s P a r a o n i s g r a c i l i s G n a t h i a c r e n u l a t i f r o n s H a lio p h a s m a g e m in a ta L eucon A M etap h o x u s f r e q u e n s A x i n o p s id a s e r r i c a t a L u m b r i n e r is c r u z e n s i s C o r r e l a t i o n 0 .5 6 9 0 .5 0 9 0 .6 0 0 0 .6 37 0 .5 0 2 0 .7 9 4 0 .7 2 3 0 .5 9 3 0 .2 6 7 0 .3 3 7 0 .3 4 6 0 .4 1 7 0 .1 4 5 * * * 0 .2 9 1 0 .4 4 7 0 .4 2 7 0 :3 2 5 ***Below t h e 0 .0 1 l e v e l o f s i g n i f i c a n c e ( r = 0 .2 5 7 ) 298 d e r i v e d d u rin g s u b s e q u e n t g ro u p in g c y c l e s . T h e re a r e two r e a s o n s f o r t h i s d e c r e a s e : s u b s e q u e n t g ro u p s a r e s m a l l e r , and th e y a re composed o f l e s s f r e q u e n t l y e n c o u n t e r e d s p e c i e s . Because th e r e c u r r e n t g ro u p te c h n iq u e i s a h i e r a r - c h a l g ro u p in g m ethod b a s e d on c o - o c c u r r e n c e a t r e l a t i v e l y h ig h l e v e l s ( I . A. = 0 .6 5 0 in t h i s s t u d y ) , t h e s p e c i e s com p r i s i n g th e g r o u p s a re n e c e s s a r i l y th e more p r e v a l e n t form s w i t h i n th e sam ple s e t . The 28 s p e c i e s c o m p r is in g t h e sev en g ro u p s d e r iv e d i n th e a n a l y s i s o f t h e e n t i r e sample s e t i n c lu d e d 21 of th e 28 s p e c i e s l i s t e d i n T able 4 . The g e n e r a l c o m p o s itio n o f g ro u p s o b t a i n e d in t h i s a n a l y s i s s t r o n g l y s u g g e s t s t h a t t h e r e c u r r e n t g ro u p s a r e p r i m a r i l y s u b d i v i s i o n s o f th e p re d o m in a n t fa u n a o f t h e e n t i r e s h e l f . When a p p l i e d t o a s m a l l sam ple -se t (176 sa m p le s) r e p r e s e n t i n g a r e l a t i v e l y l a r g e and h e te r o g e n e o u s a r e a , t h e g roups d e r i v e d w i l l in c lu d e t h a t p a r t o f th e f a u n a most c o n s t a n t o v e r th e m a j o r i t y of th e s tu d y a r e a . C o n s e q u e n tly , s p e c i f i c a r e a s o f f a u n a l d i s c o n t i n u i t y e s c a p e r e c o g n i t i o n . T h e ir f a u n a l e l e m e n ts a re to o i n f r e q u e n t in th e m a j o r i t y o f sam p les to r a t e r e c o g n i t i o n ( i . e . , t h e y la c k a f f i n i t i e s w ith th e more g e n e r a l l y d i s t r i b u t e d s p e c i e s ) . The c l a s s i c a l l y d e f i n e d L i s t r i o l o b u s a s s o c i a t i o n i s a c ase i n p o i n t . L i s t r i o l o b u s p e lo d e s has no a f f i n i t i e s w ith any o t h e r o f t h e 200 s p e c i e s c o n s id e r e d i n t h i s a n a l y s i s , and t h e r e f o r e i s n o t a member o f any r e c u r r e n t g roup. 299 Some o f th e g r o u p s d e r i v e d by t h i s m ethod a r e u n e x p e c t e d s p e c i e s c o m b in a tio n s t h a t had n o t em erged i n th e p r e v i o u s d e s c r i p t i o n o f th e m a c r o f a u n a . G roup I I I , composed o f f o u r gammarid a m p h ip o d s, i s an e x a m p le . The b i o l o g i c a l s i g n i f i c a n c e o f t h i s p a r t i c u l a r g ro u p i s n o t p r e s e n t l y known to me, b u t i t may be a v a l i d e c o l o g i c a l u n i t . One o f t h e v a l u e s o f t h i s t e c h n i q u e i s t h a t i t d o e s r e v e a l u n n o t i c e d c o m b in a tio n s o f f a u n a l e l e m e n t s , w h ic h t h e n ca n b e come th e s u b j e c t o f i n v e s t i g a t i o n t o d e t e r m i n e t h e i r e c o l o g i c a l i m p o r t a n c e . The p o s s i b i l i t y e x i s t s t h a t t h e g ro u p s d e l i m i t e d b y th e r e c u r r e n t g r o u p t e c h n i q u e a re o f g r e a t e r b i o l o g i c a l s i g n i f i c a n c e th a n t h e a s s o c i a t i o n s d e f i n e d by t h e c l a s s i c a l m eth o d . A c r i t i c a l e v a l u a t i o n o f t h e s e two a p p r o a c h e s t o f a u n a l d e s c r i p t i o n u l t i m a t e l y m ust be b a s e d on t h e s t u d y o f t h e b i o l o g y o f t h e s p e c i e s i n v o l v e d . No d i r e c t c o r r e s p o n d e n c e was fo u n d b e tw e e n t h e r e c u r r e n t g r o u p s and t h e c l a s s i c a l l y d e f i n e d a s s o c i a t i o n s . G ro u p I i n c l u d e s a number o f s p e c i e s p r o m in e n t i n t h e A m ph io d ia a s s o c i a t i o n , among them th e " d o m in a n t” o p h i u r o i d A m phiodia u r t i c a ( T a b le 14; T a b le 9, B a r n a r d and Z i e s e n - h e n n e , 1 9 6 1 ); o t h e r s l i s t e d a r e P e c t i n a r i a c a l i f o r n i e n s i s , G l y c e r a c a p i t a t a , A x in o p s id a s e r r i c a t a , P r i o n o s p i o p i n n a t a , T e r e b e l l i d e s s tr o e m i and two s p e c i e s t h a t have a f f i n i t y w i t h Group I , C h l o e i a p i n n a t a and G l o t t i d i a a l b i d a . Group I i s t h e o n l y one o f th e s e v e n g ro u p s t h a t b e a r s e v e n th e s l i g h t e s t r e s e m b la n c e t o any o f th e c l a s s i c a l l y d e f i n e d a s s o c i a t i o n s . A q u a n t i t a t i v e d i f f e r e n c e s d o e s a p p e a r i n t h e e x t e n t t o w h ich t h e d i f f e r e n t g ro u p s a r e r e p r e s e n t e d w i t h i n th e sa m p le s d e s i g n a t e d a s r e p r e s e n t a t i v e o f th e d i f f e r e n t a s s o c i a t i o n s . I n s a m p le s fro m a s s o c i a t i o n s c h a r a c t e r i s t i c o f d e e p - w a te r a r e a s (A m p h io d ia , A m p h io d ia - C a r d i t a , A m p h io d ia - O n u p h is , P e c t i n a r i a - C h l o e i a , and Amygdalum p a l l i d u l u m ) G roups I , I I , I I I , IV and VI a r e b e s t r e p r e s e n t e d q u a n t i t a t i v e l y . I n two s h a l l o w - w a t e r a s s o c i a t i o n s , N o t h r i a - T e l l i n a and D i o p a t r a , o n ly G roups I I and V a r e a t a l l w e l l r e p r e s e n t e d . The r e m a in in g a s s o c i a t i o n s o f th e s h e l f l a c k w e l l - d e f i n e d p a t t e r n s o f g ro u p d i s t r i b u t i o n and do n o t le n d th e m s e lv e s t o g e n e r a l i z a t i o n . By n a r ro w in g th e f o c u s o f t h e m ethod t o a s m a l l e r a r e a , i n s p i t e o f t h e f a c t t h a t fe w e r s a m p le s a r e em p lo y ed , d i s t i n c t i v e f a u n a l a s s o c i a t i o n s a r e i d e n t i f i a b l e w i t h e i t h e r a p a r t i c u l a r c o m b in a tio n o f g ro u p s o r a s i n g l e g ro u p . For e x a m p le , a n a l y s i s o f th e 74 s a m p le s c o l l e c t e d i n A re a s I , I I and I I I ( t h e N o r t h e r n s h e l f ) p r o v i d e s an exam ple i n w h ic h th e m a jo r c l a s s i c a l a s s o c i a t i o n s o f th e r e g i o n a r e a p p r o x im a te d by c o m b i n a t i o n s o f r e c u r r e n t g r o u p s . S am ples fro m th e A m p h io d ia - C a r d i t a a s s o c i a t i o n c o n t a i n n e a r l y a l l o f t h e N o r t h e r n S h e l f r e c u r r e n t g r o u p s . In t h e L i s t r i o l o b u s a s s o c i a t i o n , i n c o n t r a s t , o n ly G roups N -I and N - I I a r e w e l l r e p r e s e n t e d , and f o u r o f t h e 12 s a m p le s from t h i s a s s o c i a t i o n l a c k a l l g r o u p s . In th e 301 N o t h r i a - T e l l i n a a s s o c i a t i o n G roups N-IV and N - I I o c c u r i n a b o u t h a l f t h e s a m p l e s ; o n ly Group N -V III i s w e l l d i s t r i b u t e d . The A m p h io d ia - C a r d i t a , A m p h io d ia - O n u p h is and A m phiodia a s s o c i a t i o n s a re r e p r e s e n t e d by G ro u p s N -I, N - I I I and N-VI w i t h o u t N - V I I I ; th e L i s t r i o l o b u s a s s o c i a t i o n l a c k s G roups N - I I I , N -IV , N-VI and N - V II I ; and t h e N o t h r i a - T e l l i n a a s s o c i a t i o n i s r e p r e s e n t e d b y Group N - V III b u t l a c k s G ro u p s N - I I I and N-VI. When th e f o c u s of t h i s method i s f u r t h e r n a rro w e d to an a n a l y s i s o f t h e 41 s a m p le s o f t h e S a n ta B a r b a r a s h e l f a l o n e , some o f th e r e c u r r e n t g ro u p s a r e a lm o s t i d e n t i c a l i n t h e i r d i s t r i b u t i o n s t o th e c l a s s i c a l l y d e f i n e d a s s o c i a t i o n s . T hese f i n d i n g s a r e r e d u n d a n t , h o w ev er, s in c e i n two o f t h r e e c a s e s th e g r o u p t h a t m o st d i r e c t l y a p p r o a c h e s th e d i s t r i b u t i o n o f an a s s o c i a t i o n c o n t a i n s one o f th e ''d o m i n a n t s " o f t h a t a s s o c i a t i o n . G roup S B -X I, c h a r a c t e r i s t i c o f th e A m p h io d ia - C a r d i t a a s s o c i a t i o n , i n c l u d e s C a r d i t a v e n t r i c o s a a s one o f i t s two m em bers; Group SB-XIV, c h a r a c t e r i s t i c o f th e N o t h r i a - T e l l i n a a s s o c i a t i o n , i n c l u d e s T e l l i n a b u t t o n i a s one of i t s two m em bers. The t h i r d m a jo r a s s o c i a t i o n o f t h i s a r e a , t h e L i s t r i o l o b u s a s s o c i a t i o n , i s n o t d e f i n e d by a s i n g l e g r o u p . I t i s a p p a r e n t t h a t t h e r e c u r r e n t g ro u p m ethod c a n n o t b e e x p e c t e d t o d u p l i c a t e t h e r e s u l t s o b t a i n e d b y t h e c l a s s i c a l m e th o d s o f b e n t h i c a s s o c i a t i o n d e s c r i p t i o n , e x c e p t a s i t i s a p p l i e d t o v e ry l i m i t e d a r e a s . 302 The NTSYS c l u s t e r a n a l y s i s m ethod o f s p e c i e s g r o u p in g d i f f e r s from t h e r e c u r r e n t g ro u p m ethod i n b a s i n g i t s g r o u p in g s on d e n s i t y r a t h e r t h a n f r e q u e n c y o f o c c u r r e n c e ( i . e . , p r e s e n c e o r a b s e n c e i n a s a m p le ) o f s p e c i e s . The N o r t h e r n and S o u th e r n p a r t s o f th e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f w ere e a c h a n a ly z e d by t h i s m eth o d . For th e 74 s a m p le s o f t h e N o r t h e r n s h e l f ( A r e a s I , I I and I I I ) and th e 102 s a m p le s o f t h e S o u th e r n s h e l f (A re a s IV t h r o u g h V I I I ) c o r r e l a t i o n c o e f f i c i e n t s b e tw e e n s p e c i e s form ed th e b a s i s o f a " s i m i l a r i t y m a t r i x " p r o j e c t e d a s a d e n d ro g ra m . Each d e n d ro g ra m was d i v i d e d i n t o b r a n c h e s by a l i n e draw n a t th e p o i n t w here th e v a l u e o f x _ was e q u a l to + 0 .3 5 0 . Of t h e 200 s p e c i e s a n a l y z e d f o r t h e N o r t h e r n s h e l f 189 w ere i n c l u d e d i n 49 g ro u p s o f two or more s p e c i e s . They w ere d i v i d e d i n t o f i v e main d e n d r i t i c b r a n c h e s . F o u r o f th e b r a n c h e s i n c l u d e g r o u p s w h ic h r e s e m b le t h e c l a s s i c a l s h e l f a s s o c i a t i o n s . The l a r g e s t g r o u p o f B ran ch Two i s composed o f 15 s p e c i e s i n c l u d i n g T e l l i n a b u t t o n i and N o t h r i a e l e g a n s , t h e two " d o m in a n t" s p e c i e s o f t h e N o t h r i a - T e l l i n a a s s o c i a t i o n . The l a r g e s t g r o u p o f B ra n c h T h re e h a s sev en s p e c i e s i n c l u d i n g D i o p a t r a o r n a t a , f o r w h ic h a n o t h e r s h a ll o w - w a t e r a s s o c i a t i o n h a s b e e n named. B ra n c h Four i n c lu d e s f o u r g r o u p s t h a t a r e com posed o f t h e i m p o r t a n t f a u n a l e l e m e n t s o f th e o u t e r p o r t i o n o f t h e N o r t h e r n s h e l f and i t s a d j a c e n t s l o p e . T h e se a r e s p e c i e s t h a t have b e e n d e s c r i b e d as p r o m in e n t members o f t h e A m p h io d ia u r t i c a , 303 A m p h io d ia - C a r d i t a , A m p h io d ia - O n u p h is and P e c t i n a r i a - C h lo e ia a s s o c i a t i o n s . B ranch F i v e i n c l u d e s two m a j o r g r o u p s com p o se d o f a number o f p r o m in e n t f a u n a l e l e m e n t s o f t h e N o r t h e r n s h e l f a t i n t e r m e d i a t e d e p t h s ; L i s t r i o l o b u s p e lo d e s and s e v e r a l s p e c i e s c o n s i d e r e d i m p o r t a n t f a u n a l a s s o c i a t e s o f L i s t r i o l o b u s a re i n c l u d e d . F o r t h e S o u th e rn s h e l f 150 s p e c i e s w ere a n a l y z e d , y i e l d i n g a d en d ro g ram d i v i d e d i n t o t h r e e m ain b r a n c h e s . G e n e r a l l y t h e s p e c i e s o f t h i s d e n d ro g ra m w e re fra g m e n te d i n t o many s m a l l g ro u p s t h a t were d i f f i c u l t t o i n t e r p r e t on t h e b a s i s o f p r e v io u s k n o w led g e o f th e a r e a . The c o p h e n e t i c c o r r e l a t i o n v a lu e ( S o k a l and S n e a th , 1 9 6 3 ) o f 0 . 6 0 8 i n d i c a t e s t h a t a l a r g e am ount o f d i s t o r t i o n w as i n t r o d u c e d i n t h e c l u s t e r i n g p r o c e s s . F or t h i s r e a s o n o n l y two g r o u p s a r e d i s c u s s e d . A g ro u p o f f i v e s p e c i e s on B ranch One i n c l u d e s A m p h io p lu s h e x a c a n t h u s , d e s i g n a t e d a s " d o m in a n t" in an i m p o r t a n t b e n t h i c a s s o c i a t i o n on th e San Pedro Bay s h e l f ( B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). The o n l y l a r g e g r o u p of t h e d e n d ro g ra m i s on B ra n c h T h re e and i n c l u d e s 18 s p e c i e s ; A m ph io d ia u r t i c a i s one o f t h e s e . The m em bers o f t h i s g ro u p s h o u ld be c o n s i d e r e d i n any f u t u r e s t u d y and r e d e s c r i p t i o n o f t h e A m phiodia a s s o c i a t i o n . I n c o n t r a s t t o t h e r e s u l t s y i e l d e d by th e r e c u r r e n t g ro u p a n a l y s i s , a d i r e c t c o m p a riso n i s p o s s i b l e o f t h e g r o u p s d e r i v e d by th e NTSYS ^ - m a t r i x c l u s t e r a n a l y s i s w ith t h e c l a s s i c a l l y d e f i n e d a s s o c i a t i o n s of t h e N o r t h e r n s h e l f . 304 For e a c h m a jo r a s s o c i a t i o n , and some m in o r o n e s , t h e r e i s a c o m p a ra b le g ro u p . The g ro u p s and a s s o c i a t i o n s a r e by no m eans i d e n t i c a l . P e r h a p s t h e p r i n c i p a l d i s c r e p a n c y r e s u l t s fro m a l i m i t a t i o n i n h e r e n t i n th e c l u s t e r a n a l y s i s m eth o d , n am ely , t h a t a s p e c i e s may be p l a c e d i n o n ly one g ro u p on th e d e n d ro g ra m . T h e r e f o r e , a s p e c i e s l i k e A m phiodia u r t i c a , an i m p o r t a n t member o f s e v e r a l a s s o c i a t i o n s , w i l l b e i n c l u d e d i n o n ly one o f t h e i r c o m p a ra b le g r o u p s . The same c o u ld be s a i d o f su ch s p e c i e s a s P e c t i n a r i a c a l i f o r n i e n s i s , P r i o n o s p i o p i n n a t a , P r i o n o s p i o m a lm g r e n i, A x in o p s id a s e r r i c a t a , A d o n to r h in a c y c l i a , A l i g e n a r e d o n d o e n s i s and o t h e r s . The e f f e c t o f t h i s l i m i t a t i o n can be o f f s e t by a b s t r a c t i n g from t h e o r i g i n a l .r - m a t r i x a l l s p e c i e s w hich c o r r e l a t e a t a d e s i g n a t e d l e v e l w i t h any member o f th e g r o u p u n d e r c o n s i d e r a t i o n and th e n a d d in g them to th e g ro u p . I n t h i s way t h e NTSYS r_ -m a trix c l u s t e r a n a l y s i s c a n become a u s e f u l t o o l i n t h e r e d e f i n i t i o n o f a s s o c i a t i o n s f i r s t r e c o g n iz e d by t h e c l a s s i c a l a p p r o a c h . A se co n d d i s c r e p a n c y i s fo u n d i n th e i n c l u s i o n i n g ro u p s o f s p e c i e s n o t i d e n t i f i e d as p a r t o f t h e c o m p a ra b le a s s o c i a t i o n s . I t i s p r o b a b le t h a t th e o r i g i n a l d e s c r i p t i o n s o f th e l a t t e r h av e b een b a s e d on a few o b v io u s s p e c i e s , and i m p o r t a n t f a u n a l e l e m e n t s o f t h e a s s o c i a t i o n , p a r t i c u l a r l y am phipods and p o l y c h a e t e s , have b e e n c o m p le te l y i g n o r e d . By g r o u p in g s p e c i e s w i t h h ig h i n t e r - s p e c i f i c 305 c o r r e l a t i o n s a d e g r e e o f o b j e c t i v i t y i s i n t r o d u c e d i n t o th e p r o c e s s o f f a u n a l d e s c r i p t i o n . F u r t h e r c r i t i c a l e v a l u a t i o n o f t h i s m ethod can be a c c o m p lis h e d by m apping th e d i s t r i b u t i o n s o f g ro u p s g e o g r a p h i c a l l y and d e t a i l i n g t h e i r r e l a t i o n s h i p s g r a p h i c a l l y . T h is a p p r o a c h w i l l p r o v i d e d i r e c t c o m p a r is o n s o f t h e s e c l u s t e r a n a l y s i s g ro u p s w i t h t h e c l a s s i c a l f a u n a l a s s o c i a t i o n s . DISCUSSION D i v e r g e n t c o n c e p ts hav e d e v e lo p e d i n th e e f f o r t s t o d e s c r i b e th e b e n t h i c m a c r o f a u n a l a s s o c i a t i o n s o f t h e s e a , b u t one c o n c e p t p r e d o m in a te s ; th e v ie w p o i n t t h a t a s s o c i a t i o n s a r e d i s c r e t e e n t i t i e s c h a r a c t e r i z e d by p a r t i c u l a r " t y p e " or " d o m in a n t" s p e c i e s - - b i o l o g i c a l l y d e t e r m in e d a s s o c i a t i o n s or " b i o c o e n o s e s " - - h a s p r o v id e d t h e t h e o r e t i c a l fram ew ork i n w h ic h n e a r l y e v e r y b e n t h i c e c o l o g i s t h a s w o rk e d . In d e e d T h o rso n (1 9 5 7 ) h a s been a b l e to i n c o r p o r a t e th e r e s u l t s i n c l u d e d i n 119 p a p e r s by 67 d i f f e r e n t a u t h o r s i n t o h i s s y s te m o f " p a r a l l e l l e v e l - b o t t o m c o m m u n itie s ." T h a t t h i s v i e w p o i n t s h o u ld p r e d o m in a te i s n o t s u r p r i s i n g s i n c e th e l o g i c a l b a s i s f o r f a u n a l d e s c r i p t i o n i s to be s o u g h t w i t h i n t h e f a u n a i t s e l f . U n f o r t u n a t e l y t h e p r e v a i l i n g m e th o d o lo g y o f m a rin e b e n t h i c m a c r o f a u n a l i n v e r t e b r a t e e c o l o g y - - t h a t o f t h e P e t e r s e n - T h o r s o n o r D a n is h s c h o o l - - i s s u b j e c t i v e ( J o n e s , 1 9 5 0 ). T h o rs o n (1 9 5 7 , p . 476) r e c o g n i z e s t h i s l i m i t a t i o n : The i d e a l d i s t r i b u t i o n o f a s e t o f s p e c i e s c o n f i n e d t o a s i n g l e com m unity and num erous eno u g h t o d o m in a te t h e r e i s e x c e p t i o n a l i n n a t u r e , and a s a r u l e i t i s n o t e a s y t o s e l e c t th e r i g h t s e t o f s p e c i e s c h a r a c t e r i z i n g a l e v e l - b o t t o m com m unity. Com mon s e n s e com bined w i t h e x p e r i e n c e and i n t u i t i o n p l a y an e s s e n t i a l p a r t i n s e l e c t i n g su c h s p e c i e s . 306 307 T h o rs o n (1 9 5 7 ) p r o v i d e s s e v e r a l r u l e s , P e t e r s e n Ts m o d if ie d b y S p h rc h , f o r th e s e l e c t i o n o f " c h a r a c t e r i z i n g s p e c i e s . " A t t h e f i r s t o r d i n a l l e v e l he s u g g e s t s t h a t th e s p e c i e s c o n s i d e r e d f o r s e l e c t i o n be p r e s e n t . . i n a t l e a s t 50 p e r c e n t o f t h e s t a n d a r d u n i t sa m p le s and m aking a t l e a s t 5 p e r c e n t o f t h e t o t a l l i v i n g w e ig h t p e r s t a n d a r d u n i t . " One s e r i o u s l o g i c a l f l a w seem s a p p a r e n t . How d o e s one d e t a i l t h e b o u n d a r y o r l i m i t o f t h e "com m unity" (= a s s o c i a t i o n ) , i . e . how d o es one s e l e c t th e X number o f " s t a n d a r d u n i t s a m p le s " t o make t h i s d e t e r m i n a t i o n ? I t w o u ld a p p e a r t h a t th e g e o g r a p h i c l i m i t o f t h e "com m unity" m u st be known p r i o r t o t h e d e s i g n a t i o n o f t h e " c h a r a c t e r i z i n g s p e c i e s . " R u le s f o r d e t e r m i n i n g s u c h b o u n d a r i e s a r e l a c k i n g . I t i s p o s s i b l e t o make s u c h a d e s i g n a t i o n i n t h e t e r r e s t r i a l r e a lm on th e b a s i s o f l a n d s c a p e b u t n o t i n t h e " l e v e l - b o tto m " m a rin e s u b l i t t o r a l . Even w here SCUBA g e a r makes d i r e c t o b s e r v a t i o n p o s s i b l e , th e m a j o r i t y o f s p e c i e s a r e i n f a u n a l and n o t v i s i b l e t o t h e o b s e r v e r . The p o t e n t i a l a p p l i c a n t o f t h e s e r u l e s i s co n fo u n d e d f u r t h e r when he r e a d s t h a t t h i s s p e c i e s m ust be found o n ly i n one d e f i n i t e "com m unity" and o c c u r p r a c t i c a l l y e v e ry w h e re i n i t . S p e c i e s e l e c t e d to th e seco n d o r d i n a l l e v e l a r e fo u n d i n q u a n t i t i e s c o m p a ra b le t o t h o s e o f f i r s t - o r d e r s p e c i e s ; th e y o c c u r , h o w e v e r, o n ly i n c e r t a i n p a r t s o f th e com m unity. T h i r d - o r d e r c h a r a c t e r i z i n g s p e c i e s a r e fo u n d i n s t i l l 308 l a r g e r q u a n t i t i e s ( o c c u r r i n g i n a t l e a s t 70 p e r c e n t o f s a m p le s and m aking up a t l e a s t 10 p e r c e n t o f t o t a l l i v i n g w e ig h t) i n th e com m unity, b u t u n l i k e f i r s t - and s e c o n d - o r d e r s p e c i e s t h e y a r e a l s o common i n o t h e r c o m m u n itie s. T h o rs o n p r o v i d e s a number o f o t h e r r u l e s t o g u id e t h e i n v e s t i g a t o r . He e l i m i n a t e s u b i q u i t o u s s p e c i e s ; t h i s p o l i c y may be sound i n s e l e c t i n g s p e c i e s f o r c l a s s i f i c a t o r y p u r p o s e s , b u t i t i s e c o l o g i c a l n o n s e n s e i f s u c h s p e c i e s a re s u f f i c i e n t l y f r e q u e n t and a b u n d a n t t o c o n s t i t u t e an im p o r t a n t p a r t o f th e t r o p h i c s t r u c t u r e o f th e m a r in e com m unity c o n t a i n i n g t h e a s s o c i a t i o n i n q u e s t i o n . He a l s o e l i m i n a t e s p r e d a t o r y s p e c i e s and t h e r e b y o m i t s an e n t i r e t r o p h i c l e v e l . I t i s i n t e r e s t i n g t o n o t e t h a t he d o es n o t , h o w ev er, e l i m i n a t e p r e d a t o r y o p h i u r o i d s b u t r e c o g n i z e s them as c h a r a c t e r i s t i c ( " d o m in a n t” ) s p e c i e s i n s e v e r a l a s s o c i a t i o n s . One m ig h t a c c e p t t h i s a p p r o a c h t o t h e d e s c r i p t i o n o f b e n t h i c m a rin e a s s o c i a t i o n s on a u t i l i t a r i a n b a s i s i f i t w ere n o t t h a t T h o rso n c h o o s e s t o r e g a r d t h e u n i t s d e f i n e d i n t h i s m anner as " e c o l o g i c a l u n i t s " w i t h b i o l o g i c a l v a l i d i t y . He p r o c e e d s t o t h e o r i z e on t h e i r c a u s a t i o n , m a i n t e n a n c e an d s t a b i l i t y , a n d he c o n s t r u c t s a w o r ld -w id e s y s te m o f r e p l i c a t e s c r e a t e d fro m h i s r e v i e w o f t h e l i t e r a t u r e . I n t h e l a t t e r he m anages t o i n c l u d e " a s s o c i a t i o n s " d e s c r i b ed by th e p r i n c i p a l p r o t a g o n i s t o f th e " e n v i r o n m e n t a l s c h o o l , " N. S. J o n e s , 309 A number o f u n f o r t u n a t e c o n s e q u e n c e s r e s u l t from t h i s s y s te m : i t e m p h a s iz e s d i s s i m i l a r i t i e s and s u p p r e s s e s s i m i l a r i t i e s b e tw e e n n o n - p a r e l l e l (a n d p e r h a p s a d j a c e n t ) a s s o c i a t i o n s ; i t a p p a r e n t l y r e s u l t s i n th e e m p h a s is on c e r t a i n p h y l e t i c g r o u p s , th e m o llu s k s and th e e c h in o d e r m s , t o th e e x c l u s i o n o f o t h e r s , t h e p o l y c h a e t e s and th e c r u s t a c e a n s ; i t h a s g e n e r a t e d th e i d e a t h a t c o n d i t i o n s i n t h e s e a s s o c i a t i o n s a r e s im p le and e a s i l y s t u d i e d . The l a s t i d e a i s n o t s u p p o r t e d by t h e r e s u l t s o f t h i s s t u d y o r t h e e x p e r i e n c e o f t h e a u t h o r . P e r h a p s th e m o st s i g n i f i c a n t q u e s t i o n t h a t o n e can r a i s e r e g a r d i n g T h o r s o n ’s n c o m m u n itie s ’1 p e r t a i n s t o th e r e p r o d u c i b i l i t y o f h i s r e s u l t s . Would an u n b i a s e d w o r k e r , p a r t i c u l a r l y one n o t an e x p e r t i n t h e M o l l u s c a - - a p o l y c h a e t e s y s t e m a t i s t , f o r e x a m p l e - - d e v e l o p c o m m u n itie s t h a t " l o o k e d ” a t a l l l i k e T h o r s o n ’s g i v e n t h e same sam p le s e t s ? I d o u b t t h a t T h o r s o n ’s m ethods a r e s u f f i c i e n t l y o b j e c t i v e t o g u a r a n t e e r e p r o d u c i b l e r e s u l t s . B a r n a r d (t a] , i n S t e v e n s o n , 1961) ab an d o n ed T h o r s o n ’s m ethods f o r a s i m p l e r a p p r o a c h . He i d e n t i f i e d " d o m in a n t" s p e c i e s i n an a s s o c i a t i o n as t h o s e r a n k i n g f i r s t th r o u g h f o u r t h i n s t a n d i n g c r o p . T h i s a p p r o a c h seem s more v a l i d e c o l o g i c a l l y . I m p o r t a n t , w i d e l y d i s t r i b u t e d form s s u c h as A m phiodia u r t i c a c h a r a c t e r i z e th e f a u n a l a s s o c i a t i o n s and a r e n o t r e l e g a t e d t o p o s i t i o n s o f l e s s e r s t a t u s b e c a u s e o f t h e i r u b i q u i t o u s d i s t r i b u t i o n w i t h i n t h e s tu d y a r e a . P e r h a p s m ost i m p o r t a n t , a s s o c i a t i o n s w i t h s i m i l a r f a u n a l c o m p o s itio n ( e . g . , t h e o p h i u r o i d a s s o c i a t i o n s ) a r e n o t made t o seem more d i s t i n c t t h a n th e y r e a l l y a r e . C e r t a i n l y t h e d e s c r i p t i o n s o f t h e a s s o c i a t i o n s o f t h e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f by B a r n a r d and o t h e r s (B a r n a rd and H artm an, 1959; B a r n a r d and Z i e s e n h e n n e , 1961; B a r n a r d , 1963) can b e c r i t i c i z e d . They e m p h a s iz e d i s t i n c t i v e n e s s a t th e e x p e n s e o f s i m i l a r i t i e s , o m i t t i n g some w i d e l y d i s t r i b u t e d s p e c i e s ( n o t e t h e l a c k o f A m phiodia i n t h e L i s t r i o - l o b u s p i c t o r i a l p l o t , A p p e n d ix F i g u r e D - 1 5 ) ; t h e g r e a t v a r i a t i o n o f t h e d i s t r i b u t i o n a l p a t t e r n s o f t h e com ponent s p e c i e s o f any a s s o c i a t i o n i s n o t a d e q u a t e l y d e s c r i b e d ; and s m a ll b u t n u m e r i c a l l y a b u n d a n t f o r m s , p a r t i c u l a r l y p o l y - c h a e t e s and am p h ip o d s, te n d t o be o m i t t e d fro m t h e d e s c r i p t i o n s o f t h e s e a s s o c i a t i o n s . The e n v i r o n m e n ta l a p p r o a c h t o th e d e t e r m i n a t i o n o f a s s o c i a t i o n s i s th e p r o d u c t o f a d i s s e n t i n g m i n o r i t y who hav e e i t h e r become g e n u i n e l y d i s s a t i s f i e d w i t h t h e c l a s s i c a l b i o l o g i c a l a p p r o a c h on t h e o r e t i c a l g ro u n d s ( L i n d r o t h , 1 9 3 5 :1 9 6 2 ; J o n e s , 1951) o r have d i s c o v e r e d t h a t i t c o u ld n o t b e a p p l i e d t o t h e i r s t u d y a r e a ( L i n d r o t h , 1 9 3 5 :1 9 6 2 , G u llm a r F j o r d ; H artm an , 1955, San P e d r o Bay; P a r k e r , 1963, G u lf o f C a l i f o r n i a ; V i c t o r A. G a l l a r d o , p e r s . comm., Bay o f Nha T r a n g , V ie tn a m ). The e n v i r o n m e n t a l l y - b a s e d s y s te m d e v e lo p e d by N. S. J o n e s (1 9 5 1 ) a m o u n ts, h o w e v e r, t o l i t t l e 311 more th a n a lum ping and re n a m in g o f t h e P e t e r s e n - T h o r s o n " c o m m u n i t ie s -" N. A . Holme ( 1 9 6 6 , p. 4 4 8 ) s t a t e d a s much i n h i s r e c e n t p a p e r on th e b e n t h i c m a c r o fa u n a o f th e E n g l i s h C h a n n e l by p o i n t i n g o u t t h a t th e " c o m m u n itie s " he d e f i n e d d i f f e r i n " l i t t l e more th a n nam e" from t h e c l a s s i c a l " c o m m u n itie s ” d e f i n e d i n an e a r l i e r s t u d y o f t h e a r e a . The m a jo r d i f f i c u l t y w i t h th e e n v i r o n m e n t a l sy stem i s t h a t t h e l i m i t s o f v a r i a b l e s u s e d to d e f i n e c a t e g o r i e s a r e e i t h e r p u r e l y a r b i t r a r y - - t o p o g r a p h y , d e p th and s a l i n i t y - - o r a r e s u b j e c t i v e and d i f f i c u l t t o d e f i n e - - s e d i m e n t c l a s s e s s u c h a s s a n d , mud and muddy s a n d . S e d im e n t f i e l d d e s c r i p t i o n s s u c h a s t h e s e a r e , i n my e x p e r i e n c e , s u b j e c t t o v a r y i n g i n t e r p r e t a t i o n . T h e i r u se to d e l i m i t c a t e g o r i e s t h a t d e f i n e a s s o c i a t i o n s i s open t o th e same c r i t i c i s m a s t h a t l e v e l e d by N. S'. J o n e s (1 9 5 0 ) on t h e u se o f " c h a r a c t e r i s t i c s p e c i e s . " C e r t a i n l y t h e e n v i r o n m e n ta l a p p ro a c h t o d e f i n i t i o n o f a s s o c i a t i o n s i s no r e a l im p ro v em en t o v e r t h e b i o l o g i c a l a p p r o a c h . I n my o p i n i o n t h e c o m b in a tio n a p p r o a c h m e r e ly co m b in es t h e f e a t u r e s o f t h e two l e s s - t h a n - a d e q u a t e c l a s s i c a l s y ste m s and d o e s n o t r e s u l t i n a b e t t e r o n e . R an k in g a n a l y s i s i n t h e p r e s e n t i n v e s t i g a t i o n h a s d e f i n e d a p r e v a l e n t f a u n a l f r a c t i o n . T h is c o m p r is e s 24 s p e c i e s t h a t , w h ile c o n s t i t u t i n g o n ly 1 .6 p er c e n t of t h e t o t a l m a c r o f a u n a l s p e c i e s , m u st be c o n s i d e r e d a m a jo r f a u n a l e le m e n t o f t h e m a in la n d s h e l f . They r e p r e s e n t a 312 common c o n s t i t u e n t i n m ost o f t h e s t u d y a r e a (a n d t r a n s c e n d t h e r a n g e s o f t h e e n v i r o n m e n t a l v a r i a b l e s m e a su re d i n t h i s i n v e s t i g a t i o n ) , a r e b r o a d l y d i s t r i b u t e d i n m ost o f th e f a u n a l a s s o c i a t i o n s o f t h e s h e l f , and a r e t h e r e b y an i n t e g r a t i v e f a c t o r . A p r i n c i p a l l i m i t a t i o n o f th e c l a s s i c a l (D a n is h s c h o o l ) b i o l o g i c a l a p p r o a c h t o t h e d e s c r i p t i o n o f b e n t h i c a s s o c i a t i o n s i s i t s o m is s io n o f s p e c i e s i n t h i s im p o r t a n t c a t e g o r y . The im p ro v e d t e c h n i q u e s em ployed by B a r n a r d p r o v i d e d more a d e q u a t e e m p h a s is on some o f t h e s e s p e c i e s b u t f a i l e d to d e m o n s t r a t e a d e q u a t e l y t h e i r c o n t i n u i t y i n c e r t a i n s i t u a t i o n s . The e x a m i n a t i o n o f s p e c i e s d i s t r i b u t i o n r e l a t i v e t o th e d i s t r i b u t i o n o f t h e c l a s s i c a l a s s o c i a t i o n s i n w h ic h t h e y a r e c o n s i d e r e d p r o m in e n t f a u n a l e le m e n ts r e v e a l s a s e r i e s o f com plex o v e r l a p p i n g d i s t r i b u t i o n a l p a t t e r n s , t h e v a r i a b i l i t y o f w h ic h i s n o t shown by t h e c l a s s i c a l m ethods o f f a u n a l d e s c r i p t i o n . Some s p e c i e s h a v e r a n g e s t h a t c o n fo rm c l o s e l y t o t h e d i s t r i b u t i o n o f t h e a s s o c i a t i o n w i t h w h ic h th e y h a v e b e e n d e s c r i b e d as a f f i l i a t e d ; b u t o t h e r s ra n g e more w i d e l y , and o f t h e s e a few h av e b e e n d e f i n e d above as p r e v a l e n t . The s e q u e n c e o f o v e r l a p p i n g d i s t r i b u t i o n s i s c o m p a ra b le t o t h o s e d e s c r i b e d by th e g r a d i e n t a n a l y s i s t e c h n i q u e u t i l i z e d by p l a n t e c o l o g i s t s (M c In to sh , 1958; 1963; W h ita k e r , 1 9 6 2 ). A l t e r n a t i v e and s u p e r i o r m e th o d s t o t h e c l a s s i c a l 313 a p p r o a c h f o r th e d e s c r i p t i o n o f f a u n a l a s s o c i a t i o n s a r e fo u n d i n s t a t i s t i c a l g r o u p in g t e c h n i q u e s . T h e s e m eth o d s p r o v i d e a d e g r e e o f o b j e c t i v i t y and r e p r o d u c i b i l i t y d e c i d e d l y l a c k i n g i n th e o l d e r m e th o d s . The two s t a t i s t i c a l g r o u p in g t e c h n i q u e s u t i l i z e d i n t h i s i n v e s t i g a t i o n a r e b a s e d upon d i f f e r e n t c r i t e r i a : t h e r e c u r r e n t g ro u p m e th o d on c o - o c c u r r e n c e , s im p le p r e s e n c e o r a b s e n c e ; th e NTSYS r - m a t r i x c l u s t e r a n a l y s i s on p o p u l a t i o n d e n s i t y . E a c h can be u s e d t o p r o v id e u s e f u l i n f o r m a t i o n a b o u t t h e f a u n a l c o m p o s i t i o n o f th e b e n t h i c m a r in e e n v ir o n m e n t. B e c a u se t h e r e c u r r e n t g ro u p method i s b ased on c o - o c c u r r e n c e a t r e l a t i v e l y h i g h l e v e l s , t h e s p e c i e s com p r i s i n g th e g roups i n c l u d e t h e more p r e v a l e n t form s o f th e r e g i o n . The g e n e r a l c o m p o s i t i o n o f g ro u p s i d e n t i f i e d by t h i s m ethod s u g g e s t s t h a t t h e s e g r o u p s a r e m a in ly s u b d i v i s i o n s o f t h e p r e d o m in a n t f a u n a , t h e s p e c i e s most c o n s t a n t o v e r th e m a j o r i t y o f th e s t u d y a r e a . A reas o f f a u n a l d i s c o n t i n u i t y e s c a p e r e c o g n i t i o n u n l e s s th e m e th o d i s r e s t r i c t e d t o a r e l a t i v e l y s m a l l . a r e a . The g ro u p s d e r i v e d by t h i s method a r e n o t c o m p a ra b l e t o t h e c l a s s i c a l l y d e f i n e d f a u n a l a s s o c i a t i o n s . Some u n e x p e c te d c o m b in a tio n s o f s p e c i e s em erge. F u t u r e s t u d y may r e v e a l t h a t t h e r e c u r r e n t g r o u p s a r e o f g r e a t e r e c o l o g i c a l v a l i d i t y t h a n t h e a s s o c i a t i o n s o f th e c l a s s i c a l d e s c r i p t i v e s y s te m . 314 R e s u l t s fro m th e NTSYS r - m a t r i x c l u s t e r a n a l y s i s a r e more d i r e c t l y r e l a t e d t o t h e c l a s s i c a l l y d e f i n e d b e n t h i c a s s o c i a t i o n s - H ow ever, t h e s p e c i e s c l u s t e r s and a s s o c i a t i o n s a r e n o t i d e n t i c a l . Two b a s i c d i s c r e p e n c i e s e x i s t ; a s p e c i e s can be p l a c e d o n ly once i n t h e d en d ro g ra m a l t h o u g h i t may o c c u r i n more th a n one c l a s s i c a l l y d e f i n e d a s s o c i a t i o n ; t h i s l i m i t a t i o n may be e a s i l y o f f s e t by r e f e r e n c e t o t h e o r i g i n a l c o r r e l a t i o n m a t r i x . S e c o n d ly , im p o r t a n t f a u n a l e l e m e n t s , p a r t i c u l a r l y am phipods and p o l y - c h a e t e s , t h a t w e re c o m p l e t e l y i g n o r e d i n t h e c l a s s i c a l d e s c r i p t i o n o f an a s s o c i a t i o n w i l l b e i n c l u d e d i n i t s com p a r a b l e s p e c i e s c l u s t e r g r o u p . T h i s f a c t o r i s one o f th e d e c id e d a d v a n ta g e s o f t h i s m eth o d . F u r t h e r c r i t i c a l e v a l u a t i o n o f t h i s m ethod w i l l u n d o u b te d ly e n h a n c e i t s v a l u e as a t o o l f o r f a u n a l a n a l y s i s . A d e q u a te e v a l u a t i o n o f s t a t i s t i c a l a p p r o a c h e s t o t h e d e s c r i p t i o n o f t h e b e n t h i c m a c ro fa u n a a w a i t s b r o a d e r a p p l i c a t i o n o f t h e s e m ethods i n t h e f u t u r e . The s p e c i f i c s t a t i s t i c a l p r o c e d u r e s em ployed i n t h i s i n v e s t i g a t i o n p r o b a b l y w i l l be r a t h e r q u i c k l y s u p p l a n t e d by more r e f i n e d t e c h n i q u e s . N e v e r t h e l e s s , th e a u t h o r i s c o n v in c e d t h a t o b j e c t i v e s t a t i s t i c a l m eth o d s w i l l so o n c o m p l e t e l y r e p l a c e t h e c l a s s i c a l m eth o d s h i t h e r t o u t i l i z e d f o r t h i s p u r p o s e . CONCLUSIONS The e x p e r i e n c e I have g a i n e d d u r i n g th e A l l a n H ancock F o u n d a t i o n S u rv e y o f t h e s o u t h e r n C a l i f o r n i a n m ain la n d s h e l f c o u p le d w i t h th e r e s u l t s o f t h e p r e s e n t s t u d y le a d s me t o f o r m u l a t e t h e f o l l o w i n g c o n c l u s i o n s : 1. B e n t h i c m a rin e a s s o c i a t i o n s a r e n o t d i s c r e t e assem b l a g e s o f o rg a n is m s b o u n d t o g e t h e r by t h e b i o l o g i c a l i n t e r a c t i o n s o f t h e i r co m ponent s p e c i e s or d e te r m in e d b y p r e c i s e l i m i t s o f t h e e n v ir o n m e n t- They a r e , r a t h e r , r o u g h l y d e f i n a b l e u n i t s , w i t h f a i r l y r e c o g n i z a b l e g e o g r a p h i c l i m i t s , c o n s i s t i n g o f o r g a n is m s t h a t h a v e some s i m i l a r r e a c t i o n s t o t h e i r t o t a l e n v i r o n m e n t, th e p h y s i c a l and b i o l o g i c a l f a c t o r s ta k e n t o g e t h e r . P r o b a b ly n o two s p e c i e s have i d e n t i c a l r e a c t i o n p a t t e r n s t o t h e i r t o t a l e n v ir o n m e n t. T h e most a c c u r a t e d e s c r i p t i o n o f th e a c t u a l d i s t r i b u t i o n o f o r g a n ism s l i e s somew here b e tw e e n th e i d e a o f " b i o c o e n o s i s " and t h e i d e a o f c o n tin u u m w i t h o u t d i s c o n t i n u i t i e s . The d i s t r i b u t i o n o f s p e c i e s i n t h e form o f a s e r i e s o f o v e r l a p p i n g p a t t e r n s a lo n g a c o n tin u u m no d o u b t i s t r u e f o r a l l i n d i v i d u a l s p e c i e s f o r a l l c o n tin u a t h a t one m ig h t d e f i n e . The m u l t i p l e f a c t o r r e l a t i o n s h i p s o f t h e s e many s p e c i e s c o n t i n u a w i l l i n v a r i a b l y r e s u l t i n some a r e a s o f common 316 e x p r e s s i o n ; t h e s e a r e th e a s s o c i a t i o n s . The n o n - d e f i n a b l e a r e a s b e tw e e n a r e t h e e c o t o n e s , a r e a s o f no c e r t a i n d e f i n i t i o n . I n a s e n s e t h e a s s o c i a t i o n i s i n th e mind o f t h e b e h o l d e r , b u t so m e th in g i s t h e r e t o b e h o l d . 2 . The term " d o m in a n t" a s i t h a s b e e n em ployed i n b e n t h i c m a rin e a s s o c i a t i o n d e s c r i p t i o n s i s m e a n in g f u l o n ly i f i t can b e c o n c l u s i v e l y d e m o n s t r a t e d t h a t th e s p e c i e s i n q u e s t i o n i n f a c t a r e t r o p h i c d o m i n a n t s . R e s e a r c h w h ic h w ould e s t a b l i s h t h i s ty p e o f d om inance h a s n o t b e e n c o n d u c t e d on any o f t h e s p e c i e s s o d e s i g n a t e d i n t h e p r e v i o u s d e s c r i p t i o n s o f t h e b e n t h i c m a c r o f a u n a l a s s o c i a t i o n s o f t h e s o u t h e r n C a l i f o r n i a n s h e l f . I n much o f th e t r a d i t i o n a l b e n t h i c m a rin e e c o l o g y "d o m in a n c e " h a s b e e n assum ed by i n v e s t i g a t o r s t r y i n g t o im p re s s t h e i r f i n d i n g s i n t o t h e mold c r e a t e d by th e D a n is h s c h o o l o f t h o u g h t ( T h o rs o n , 1 9 5 7 ). S p e c i e s d e s i g n a t e d a s " d o m in a n ts " m o st o f t e n a r e o n ly t h o s e o b v io u s fo rm s , t h e " c h a r a c t e r i s t i c s p e c i e s " , f o r w h ic h t h e c o m m u n itie s a r e named and by w h ic h t h e y a r e i d e n t i f i e d . I n th e s o u t h e r n C a l i f o r n i a n a r e a , p e r h a p s a c a se c o u ld be made f o r L i s t r i o l o b u s p e l o d e s a s an a s s o c i a t i o n d o m in a n t. I t s p resu m ed m ethod o f f e e d i n g ( J . L. B a r n a r d , p e r s . comm.) by n o n s e l e c t i v e l y l a p p i n g t h e s u r f a c e s e d i m e n ts i n t h e a r e a s a t th e o p e n in g o f i t s b u rro w may a c t u a l l y be a f a c t o r i n l i m i t i n g t h e e s t a b l i s h m e n t o f o t h e r o rg a n is m s i n th e com m unity. H ow ever, t h i s r e l a t i o n s h i p i s 317 o n ly s u r m i s e d . The t h i c k m ats o f t u b e s p ro d u c e d by th e p o l y c h a e t e , C h a e t o p t e r u s v a r i o p e d a t u s , may e x e r t a p r o n o u n c e d i n f l u e n c e i n t h i s com m unity, b u t on w h at a n d how i s n o t known. I n th e o p h i u r o i d a s s o c i a t i o n s p r e d a t i o n by t h e s u g g e s t e d " d o m in a n t” o p h i t i r o i d s may p l a y a n i m p o r t a n t r o l e i n m a i n t a i n i n g th e c o m p o s i t i o n o f t h e s e f a u n a l a s s e m b l a g e s , b u t t h i s r o l e can o n ly be i n f e r r e d fro m r e s e a r c h i n o t h e r a r e a s (T h o rs o n , 1957; B o o l o o t i a n , 1 9 6 6 ); i t h a s n o t b e e n d e m o n s t r a t e d f o r th e s o u t h e r n C a l i f o r n i a n r e g i o n . As a m e a n in g f u l te rm , d o m in a n t s h o u ld n o t b e u s e d w h ere th e b i o l o g y o f t h e s e s p e c i e s i s f o r t h e m o st p a r t unknown. The a n im a ls s e l e c t e d t o i d e n t i f y a s s o c i a t i o n s s h o u ld be t h e more o b v io u s ( e a s i l y r e c o g n i z a b l e and i d e n t i f i e d ) s p e c i e s h a v in g many h i g h c o r r e l a t i o n s w i t h o t h e r fo rm s ( b r o a d l y d i s t r i b u t e d a s s o c i a t i o n s ) o r few h i g h c o r r e l a t i o n s w i t h o t h e r fo rm s ( l i m i t e d , u n iq u e a s s o c i a t i o n s ) . T h e i r i m p o r t a n t f a u n a l a s s o c i a t e s s h o u ld be i d e n t i f i e d by some o b j e c t i v e s t a t i s t i c a l m ethod s u c h as h i g h c o r r e l a t i o n s . The b i o l o g y o f th e s p e c i e s i n c l u d e d i n s u c h c o m b in a tio n s s h o u ld be t h o r o u g h l y s t u d i e d . 3. The c o n c e p ts o f s u c c e s s i o n and c lim a x h av e p la y e d no g r e a t p a r t i n t h e t h i n k i n g o f m o st m a r in e e c o l o g i s t s . S h e l f o r d and h i s a s s o c i a t e s a r e an e x c e p t i o n t o t h i s s t a t e m e n t. T h is o m i s s i o n i s u n f o r t u n a t e , f o r i n a r e g i o n s u c h a s t h e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f t h e s e c o n c e p ts may b e a p p l i e d , a t l e a s t t e n t a t i v e l y , i n an e f f o r t to u n d e r s t a n d b e t t e r t h e f a u n a l s t r u c t u r e o f th e r e g i o n . I t i s s u g g e s t e d t h a t t h e A m p h io d ia u r t i c a com m unity and r e l a t e d c o m m u n itie s i n d e e p e r w a t e r , t h e N o t h r i a - - T e l l i n a community i n s h a l l o w e r w a t e r , and p e r h a p s th e P r i o n o s p l o m alm g ren i com m unity i n th e i n s h o r e zo n e a r e t h e p r i n c i p a l m a c ro fa u n a o f th e s h e l f . T h a t i s , t h e s e a n im a l a s s o c i a t i o n s , ho w ev er i n c o m p l e t e l y d e f i n e d , a r e th o s e t o be p r e d i c t e d w i t h i n t h i s r e g i o n . M arked d e v i a t i o n s fro m th e g e n e r a l e n v ir o n m e n t i n any z o n e , p r i n c i p a l l y i n t h e way o f s u b s t r a t e c o m p o s i t i o n w i l l be p o p u l a t e d by e q u a l l y d e v i a t e f a u n a l a s s e m b l a g e s . The m ore e x tre m e t h e s u b s t r a t e , th e more d i s t i n c t i v e t h e f a u n a t h a t w i l l i n h a b i t i t . The Las P i t a s Mud d e p o s i t and th e r e l i c r e d s a n d s a r e e x a m p le s o f s u c h d e v i a t i o n s . E a c h i s i n h a b i t e d b y a v e r y d i f f e r e n t f a u n a l a s s e m b la g e t h a n t h a t d i s t r i b u t e d o v e r m o st o f th e s h e l f . The l a c k o f c o r r e s p o n d a n c e b e tw e e n t h e s e f a u n a l e x tre m e s and t h e g e n e r a l f a u n a h a s b e e n d e m o n s t r a t e d . T h e s e v a r i a n t f a u n a l a s s o c i a t i o n s may b e c o n s i d e r e d s e d im e n t s u b - c l i m a x e s . I t i s n o t d i f f i c u l t t o c o n c e iv e t h a t some s l i g h t c h a n g e — one t h a t w ould n o t g r e a t l y a l t e r th e g e n e r a l c h a r a c t e r o f t h e e n v ir o n m e n t o f t h e s h e l f - - c o u ld e r a d i c a t e t h e s e a r e a s . D e p o s i t i o n m ig h t someday f i l l th e a r e a b e h i n d t h e C a r p i n t e r i a R i s e , a l t e r i n g t h e c o n d i t i o n s o f t h e s e d im e n ts i n w h ic h th e L i s t r i o l o b u s fa u n a d w e l l s . What w i l l h a p p e n t o t h i s d i s t i n c t i v e com m unity 319 t h e n ? ( I t i s n o t e v e n known i f t h i s com m unity i s a r e p r o d u c t i v e community o r i s m a i n t a i n e d by l a r v a e fro m d e e p e r w a t e r o r fro m a r e a s n o r t h o f s o u t h e r n C a l i f o r n i a . ) The c o a r s e r e d s a n d d e p o s i t s may be c o v e r e d by f i n e r s e d im e n ts a t some t i m e , r e s u l t i n g i n t h e e l i m i n a t i o n o f t h e N o t h r i a - - S p io p h a n e s com m unity. Such o c c u r r e n c e s r e p r e s e n t a p o s t u l a t e d r e t u r n to w a rd t h e more g e n e r a l c o n d i t i o n s o f t h e r e g i o n . I n a s e n s e t h e more o b v io u s and d i s c r e t e c o m m u n itie s s u c h as t h e L i s t r i o l o b u s com m unity a r e th e l e a s t i m p o r t a n t f e a t u r e o f th e b i o t a o f a r e g i o n . O f t e n , h o w e v e r, t h e y r e c e i v e th e g r e a t e s t s h a r e o f th e a t t e n t i o n - - t h e y a r e n o t u n l i k e t h e r a r e and i n t e r e s t i n g s p e c i e s o f t h e t a x o n o m i s t . 4. A d d i t i o n a l s a m p lin g and a n a l y s i s o f t h e s e s a m p le s w ould p r o v i d e a b e t t e r d e s c r i p t i o n o f th e f a u n a o f t h e r e g i o n . S p a t i a l d i s t r i b u t i o n s c o u ld be c l a r i f i e d , t e m p o r a l v a r i a t i o n s c o u ld b e e x p l o r e d , and c a u s a l r e l a t i o n s h i p s c o u ld be i n t e r p r e t e d . N o n e t h e l e s s , l i t t l e c e r t a i n t y i n any o f t h e s e m a t t e r s w i l l be a c h i e v e d w i t h o u t d e t a i l e d s t u d i e s o f th e b i o l o g y o f t h e i n d i v i d u a l s p e c i e s i n v o l v e d . APPENDIX A TABLES AND FIGURES OF THE TEXT 320 APPENDIX TABLE A - l . The O r i g i n a l S t r a t i f i e d Sample o f 176 S am ples. The numbers a re V e le ro IV S t a t i o n Numbers. Area I A rea I I A rea I I I A rea IV A rea V Area VI A rea VII A rea V III 10 fath o m 4810 4782 5043 5730 4806 4718 ' 4758 4744 D epth 4819 4840 5535 5739 4720 4761 4908 C la s s 4822 4841 5965 4869 4774 4917 5564 4843 5966 5501 4862 4922 4825 5740 4867 4928 4956 » 4877 4931 5165 5373 6059 20 Fathom 4787 4839 ,r 5045 5539 4802 4719 4762 4743 D epth 4938 4845 5111 5709 4721 4769 4927 C la s s 5161 5166 5729 5741 4771 5189 5262 5732 5742 4775 5614 5331 5743 4777 5402 5751 5772 5410 5752 5831 5754 5832 5835 5836 30 Fathom 4785 4826 4850 5098 None 4722 4871 4745 D epth 4786 4783 5533 5538 5087 5202 4746 C l a s s 4817 4827 5710 5744 5372 4910 5163 5167 5731 5750 5193 5261 5735 . 5330 C O 5413 C O 4781 M APPENDIX TABLE A-l. (Continued) A rea I A rea I I A rea I I I A rea IV A rea V. A rea VI A rea V II A rea V I II 40 Fathom 4824 5168 5042 5537 4855 5748 4768 4918 D epth 5171 5421 5728 4859 4924 C la s s 5563 5259 5734 5108 4935 5568 5586 5737 5558 5873 5998 50 Fathom . 4784 4828 5255 5536 5029 5745 4772 4747 D epth 4820 4837 5733 5749 5370 4757 C l a s s 4821 4951 5736 5774 4920 5160 5173 5886 5603 5174 50-100 4939 4783 4835 5712 None 5746 4760 4753 Fathom 5162 4980 4851 5713 4767 4936 D epth 5169 5738 4776 5375 C l a s s 5258 4878 5325 5092 i I 58 28 5 8 1 3 I O J w C O APPENDIX FIGURE A-l A Map Showing th e L o c a tio n s o f th e F o u r te e n C h a r t s I l l u s t r a t i n g t h e A l l a n Hancock F o u n d a tio n S u rv e y S t a t i o n L o c a t i o n s ( F ig u r e 1 . 5 , AHFrUSC, 1 9 6 5 ). 323 f LO CA TIO N S O F M A ST E R CH A RTS SCALE1 STATUTE MLES Figure A- APPENDIX FIGURES A-2 to A-15 C h a r t s o f t h e A lla n H ancock F o u n d a tio n S u rv e y S t a t i o n Lo c a t i o n s . 325 1 1 7 * 0 7 ' CHART 1 STATION LOCATIONS • IhM DIEGO N A U T I C A L M I L E S LEGEND I SAN DIEGO 0 TEW3 . S A L .,O X Y G E N 0NUTRENTS 0 PLANKTON (^TRANSPARENCY 0BENTHC B IO L O G Y 0 G E O L O G Y NORTH ISLAND 5073 _6585 5614 ® ffi^ 7 0 2 0 NTERTBAL A L G A E 6412 641 4932 © 4 9 2 9 © 5860 5756 5 8 8 ^ j © 4 9 0 4914 © 9 5 6 8 3 ©«* INTERNATIONAL OUTFALL • * “ S L 6506® »N S2 5 1 9 1 © © 6587 ® 4748® 4747 8 5 # d ® U&A. '■ " ® 5 MEXICO 4745 V © 4750 569 V 5 8 3 © II7°07' CO I N i O' Figure A-2 I7®30 CHART 2 STATION LOCATIONS 6 6 0 9 5 0 6 1 5 B B 7 © ® ® © 5 7 7 1 5 0 6 2 0 N A U T I C A L M I L E S LEGEND y TEMR.SAL., O X Y G E N ▼•NUTRIENTS ^ PLANKTON ^TRANSPARENCY B E N T H IC B IO L O G Y G E O L O G Y N TERT1DAL A LGAE 6 5 7 4 6 5 7 5 „ © e 6 57^ 6 6 0 1 6 6 0 0 f f l 6 5 9 9 © 6 5 9 8 © m 6 5 9 3 8 0 8 5 ® 4 9 1 8 5 7 6 8 „ 4 9 B /LA JOLLA PACIFIC BEACH 4 9 2 3 0 ^ 5 7 6 4 © 5 7 6 6 117*12' O J C O w < 1 Figure A- CHART 3 STATION LOCATIONS M A R G A R I T A R I V E R N A U T I C A L M I L E S LEGEND */■ TEMP. SftL, O X Y G E N ▼•NUTRIENTS 0 PLANKTON ^TRANSPARENCY ^ BENTHC B IO L O G Y R I V E R O C E A N S I D E O U T F A L L 908 9 7 1 0 OCEANSIDE NTERTIDAL ALGAE • 6077 • 5890 CARDIFF THE-SEA F ig u r e I7°45' sxetm etr-ssvnsn - u r s v n i r r w o L s r a 'K r i DANA PONT OUTFALL ‘ 6 K a i l 7 ^ S ^ 3 S r 2 0 « ’ ) 35' 30' IIT 2 r SAN CLEMENTE OUTWLL SAW CLEMENTE CHART 4 STATION LOCATIONS = § = NAUTICAL MLES LEGEND TEMR S A L .,O X Y G E N £ ) NUTRIENTS PLANKTON TR A N S P A RE N C Y B E W THC B O L O G Y G E O L O G Y NTERTCAL ALGAE 5 9 0 1 ® 5 0 4 7 5 6 3 3 , 5 6 2 1 SAN MffTEDPT 6 3 6 3 5 0 4 9 ^ 6 3 8 0 9 6 3 6 1 6 3 6 2 6 3 8 5 V . / B 2 4 f t. * S 204.se A 6 5 8 8 . 6 3 8 9 ^06 9 6 2 8 « ( i 5 0 S 4 4 7 » W ^ ^ 7 0 0 9 6 5 6 5 ^ 4 7 E 6 117*27 > 1 U l II7V5' 0 0 W v O F ig u r e [|7®45 i i e ° o c r CHART 5 STATION LOCATIONS N A U T I C A L M L E S LEGEND A .'. TEMP,SAL,OXYGEN NUTRENTS PLANKTON TR A N S P A R E N C Y BENTHC B IO L O G Y GEOLOGY HUNTINGTON BEACH NTERTIO AL ALGAE ORANGE COUNTY OUTFALL 5 0 0 5 9 0 1 3 7 0 0 4 ■saAw DEL MAR t f 0 6 5087 99 9 3 7 4722 L A C U N A B E A C H O U T F A L L SOUTH LAGUNA BEACH OUTFALL LAGUNA BEACH in~45' e w 00 U ) o F ig u re 06' B33 SAN SEAL BEACH WHTE’S POINT OUTFALL LONG S A N P E D R O e a r ■BIT e ie 6364 > 1 0 3 6 0 0 4 0 ‘ |3» © 6099 '3750 5820 35 CHART 6 H J 6 * STATON LOCATIONS 3953 3 7 4 6 • 6 0 9 8 3 7 4 7 NAUTICH. ULE5 LEGEND TEMP.SAL. .OXYGEN NUTRIENTS PLAMCTON C fQ T R A N S P A R E N C Y B E N T H C a O L O G Y G E O L O G Y 05' O J O J yy 3 4 * 00' Sb240 698^ 5707^ ^ C *5 7 0 3 ^*3 9 9 0 4 * 4 7 0 0 3 % .VENICE 69621 }«7*?*-lie**J*0*) 0 , • 5 5 ' M A N H A T T A N BEACH 2 5 * 3 0 * 3 5 ' Figure A-8 oo 00 D O 1 1 8 * 5 0' 45* 40' 35* 30' 3 4 * " 10' 0 5 * ' ne*25/ CHART 6 STATION LOCATIONS Wt/DCAL MILES LEGEND £ > t e m p.s a u jx y g e n 4NUTR£NTS A r jw k t o n i TRANSR&RENCY EENTMC BICLOGY -r1 ^GE O L O G Y =!==? 05' SA N T A MONCA B 3 4 U A U 8U PT 5824 5708 SANTA MONICA » 7 S ^ H T E R T O A L AUGAE P M ] yr l-ocr 1 1 6 * 5 0 ' iia* 25- F ig u r e A-9 G J co co Figure A-10 05* PTMUGU 05' B 3 B 4 05* CO CO 4^ 335 Figure A-ll 1 1 9 ° 2 9 ' 119*16' CHART 10 STATION LOCATIONS NAUTICAL MLES LEGEND RINCON P T TEM?,SAI_OXYGEN NUTRENTS PLANKTON T R A N S P A R E N C Y BENTHC B IO L O G Y GBXOGY .GO RbA 6 3 0 8 # 5 2 6 3 • NTERTIDAL ALGAE PT LAS PITAS B 3 2 6 9 6 9 M S S ^ 6 1 6 6 5 3 3 3 5 2 6 2 WV6 0 1 e V E N T U R A O U T F A L L £ £ 5 3 3 6 6966864 5328 5 5 9 7 5 3 2 7 ® 5 3 4 0 ® 5 6 7 n l i 6 5 2 4 T C 6 9 6 5 6 0 7 6 2 2 0 6 2 2 4 6 T m liy 6 ' 3c r le^oo* BILTMORE HOTEL OUTFALL SUMMERLANO O U T FA LL MONTECfTO SANTA BARBARA OUTFALL S A N T A B A R B A R A m OUTFALL LOON PT rTfp407B“ 5394Tjg6a 49^ s tw im u I A t BIOLOGY | X 5 4 0 fc-54CC 5 4 0 3 ^ * 3 & - - - - - - - - - - - 1 5 3 2 1 » 9 5 4 0 4 1 | 5 2 6 8 ? • • 5 4 0 8 l * * 5 4 0 6 L r £ 5 5 8 2 5 4 0 6 | 0 | Y 4 9 8 3 4 9 7 7 r 5167 T 5 2 6 9 % m 4027 5270 6 6 6 5 1 5 531 4ggi * * 5 3 2 3 4 9 6 2 a Q L O G Y 5 0 6 3 R G R O A 9 8 6 7 ^ 6 0 2 0 0 5 9 6 8 5 5 7 3 % T4 82 B CARPENTERIA OUTFALL 5 4 0 9 5 4 U 6 7 2 4 _ _ _ % '5 4 0 ® 60* \ 5 5 6 5 % ' 5 4 1 3 * 5 5 8 3 5 4 1 7 5 2 6 7 4 6 2 6 4*- V 5 T 7 6 £ 5 5 8 4 6 9 6 1 5 4 6 6 5 2 0 ^ 5 4 9 5 4 1 4 ~ 5 4 ) 5 ^ 6 5 2 1 6 9 6 2 6521 ^506 1 5 ' - CHART 1 1 STATION LOCATIONS ° 1 2 ' N A U T I C A L M I E S LEGEND TEMP. SAL,OX>pEN -^N U T R IE N T S -^P L A N K T C N -^TRA N SPA REN CY -^-B E N T H C BIOLOGY ^-G EO LO G Y ________ 5 4 a % 6 3 © 6 6 2 2 ^ 3 7 4 5 1 7 5 ♦♦5857 f I N T E R T I D A L ALGAE 5 3 2 5 ^8964 '6523 ♦ ♦ s e e ♦ ♦ 5 6 5 8 * 5 6 7 0 34' I I ' Wilt* brcten lin e ll?35T6M9«W50'-T (re th e fd o w n g G eckxjc locations' 5268,58485850-52,5854,58646018, | 6026.6030-32607-43.6(46-4r — 6270-75 S 6282-6288. i^Trjr 40 N S 2 T & : Jlis centered 7wHh stations' lj6£36-44 a £f is centered stations' 5 3 a r 5l73 5 5 9 0 ^6 3 4 ¥ 5 8 7 1 * - 6 1 3 4 0tB X 6163 f t V 5 2 5 8 1 5 ' r 35' 30'190 2 9 0 0 ' O J C O cr> Figure A -12 337 Figure A-13 II9°55 45' i & w z c r COAL OIL 5161 5 6 6 6 PT. 6 2 6 6 6 9 6 6 1 ^ ^ 3 1 4 6064 < 1 !SI3 6 9 6 4 4 6 0 9 20 ' 4 6 0 6 , 15' •- 34° II' CHART 12 STATION LOCATIONS o I N A U T I C A L M I L E S LEGEND } TEM?,SAL, OXYGEN ) NUTRIENTS ) PLANKTON ^TRANSPARENCY )BENTHC BIOLOG Y ) GEOLOGY .6015 5317 5 1 7 0 @ 5 3 3 6 INTERTDAL AUGAE 20 15' II9°55' 5 0 45' II9°43'30 34* I' I 2 0 ° 2 0 * 3 4 * - 3 0 ' 2 5 * • 2 C r 4 6 T 6 0 A 6509 • * 6950 6259 6506 * $ 6256 6949 CHART 13 STATION LOCATIONS NAU TIC AL, M L £ S LEGEND < > 6 2 5 7 - T E M i S A U O X Y G E N - 7 t t t J T R E N T S - ^ P L A N K T O N . N p T R A N S P A R E N C Y - ^ - B E N T H C B J O L O G Y ^ - G E O L O G Y QAV10TA 4822 * 0 9 9 9 9 r -# S S 1 B*^364 4937*^3563 53C I n t e r t o a l a l g a e 120* 20' 1 0 ' B 2 0 U N T O «OQO0 * 4 7 3 5 6 0 0 ^ 6002 0 ^ e o o 3 0 5 ' 60040 1 2 0 *00' 1 1 9 * 5 5 ' CAPITAN 6 9 5 3 4 Q 2 3 6261 0 6 5 * ^ t«E 4 6006 c* 6007 6 000 0 5 ' 120*00' 3 4 * 3a • 2 5 ' F i g u r e A -14 338 30' 34° 35' 34c CHART 1 4 STATION LOCATIONS PT ARGUELLO NAUTICAL MILES LEGEND ■TEMP.SAL.OXYGEN T ; NUTRIENTS ^•PLANKTON TRANSPARENCY ^B E N T H C BOLOGY 2 } GEOLOGY 461 3 48 15 ■30' |HINTERTIDAL ALGAE F ig u r e A -15 PT CONCEPTION 5 1 64 5558 4 8 1 1 ■ 2 5 ' .5995 6235 9 6256 20" 25' 35' 3 0' APPENDIX TABLE A -2 . D a ta C a rd F o rm a t. L i s t e d a r e th e ite m s o f d a t a , th e c a r d f i e l d s u s e d f o r e a c h i te m an d th e s o u r c e o f e a c h ite m . I te m o f D a ta C a rd F i e l d (C olum ns) S o u rc e BIOLOGICAL DATA CARD S t a t i o n Number 6 L a t i t u d e 10 L o n g itu d e 16 D e p th ( i n m e te r s ) 23 G roup ( € ,E ,M ,0 , o r P) 28 G enus ( o r F i r s t Name) 29 S p e c ie s ( o r S eco n d Name) 53 Number o f S p ecim en s 77 ENVIRONMENTAL DATA CARD #1 S t a t i o n Number 6 Latitude 10 9 T a b le s V IIA , V IIB , V IIC ; AHF: USC, 1965; A p p e n d ix — D ata 15 Same a s a b o v e . 22 Same a s a b o v e . 27 Same a s a b o v e . Same a s a b o v e . 52 Same a s a b o v e . 76 Same a s a b o v e . 80 Same a s a b o v e . 9 T a b le 1; AHF:USC, 1965; A p p e n d ix --D a ta 15 Same as above. 340 APPENDIX TABLE A-2 (Continued) I te m o f D a ta C ard F i e l d L o n g itu d e 16 D e p th , i n m e te r s 23 G e a r , 1 = OPG; 2 = C a m p b e ll; 3 = Van V een 28 D a te 29 T e m p e r a tu r e , °C , b o tto m 10 35 m e te r s S a l i n i t y , ° / o o , b o tto m 10 m e te r s 38 V olum e, i n l i t e r s 50 S e d im e n t Type 53 % G r a v e l 55 % Sand 59 - % S i l t 63 - (C o lu m n s) 22 27 34 37 40 52 54 58 62 66 S o u rc e T a b le 1; AHF:USC, 1965 A p p e n d ix - -D a ta T a b le s V IIA , V IIB , VIIC AHF:USC, 1965; A p p e n d ix -- D a ta Same a s a b o v e . D e le te d fro m M a s te r Tape T a b le I I ; AHF: USC, 1965; A p p e n d ix — D a ta Same a s a b o v e . T a b le V IIA , V IIB , V IIC ; AHF:USC, 1965; A p p e n d ix - - D a ta D e le te d fro m M a s te r Tape T a b le IV; AHF:USC, 1965; A p p e n d ix - -D a ta Same a s a b o v e . Same a s a b o v e . ^ APPENDIX TABLE A-2. (Continued) Ite m o f D a ta % C la y M edian d i a m e t e r , m i l l i m e t e r s S e d im e n t t e m p e r a t u r e , °C S o r t i n g C o e f f i c i e n t ENVIRONMENTAL DATA CARD # 2 S t a t i o n Number % N i t r o g e n , s e d im e n t % C a lc iu m c a r b o n a t e , s e d im e n t P o l y c h a e t e s , w e t w e i g h t , gram s C r u s t a c e a n s , w e t w e ig h t, gram s C a rd F i e l d (C olum ns) S o u rc e 67 - 70 T a b le IV; AHF:USC, 1965; A p p e n d ix — D ata 71 - 73 Same a s a b o v e . 74 - 76 T a b le V IIA , V IIB , V IIC ; AHF:USC, 1 965; A p p e n d ix — D a ta 78 - 80 T a b le IV; AHF:USC, 1965; A p p e n d ix — D a ta 6 - 9 T a b le IV; AHF:USC, 1965; A p p e n d ix — D a ta . 10 - 12 Same a s a b o v e . 13 - 15 Same a s a b o v e , 16 - 20 T a b le V IIA , V IIB , V IIC ; AHF:USC, 1965; A p p e n d ix — D a ta 21 - 24 Same a s a b o v e . 342 / I APPENDIX TABLE A -2 . ( C o n tin u e d ) I te m o f D a ta E c h in o d e rm s , w e t w e i g h t , gram s M o llu s k s , w et w e ig h t, gram s O th e r g r o u p s , w e t w e ig h t, gram s L i s t r i o l o b u s , w et w e i g h t , gram s A s s o c i a t i o n Type S e d im e n t Type O xygen, w a t e r , b o tto m 10 m e t e r s , mg,/l N i t r a t e , w a t e r , b o tto m 10 m e t e r s , mg./l P h o s p h a te , w a t e r , b o tto m 10 m, mg./l S i l i c a t e , w a t e r , b o tto m 10 m, m g/1 A re a , g e o g r a p h ic C ard F i e l d (C olum ns) 25 - 28 29 - 32 33 - 37 38 - 4 2 43 - 44 45 46 - 48 49 - 51 52 - 54 55 - 57 58 S o u rc e T a b le V IIA , V IIB , V IIC ; AHF:USC, 1965; A p p e n d ix — D a ta Same as a b o v e . Same a s a b o v e . Same a s a b o v e . A p p e n d ix T a b le A -3 D e l e t e d fro m M a s te r T ape T a b le I I ; AHF:USC, 1965; A p p e n d ix — D a t a ; D e le te d fro m M a s te r Tape T a b le I I ; AHF:USC, 1965; A p p e n d ix — D a ta Same a s a b o v e . T a b le V IIA , V IIB , V IIC ; AHF:USC, 1965; A p p e n d ix - - D ata 343 344 APPENDIX TABLE A -3 . A s s o c i a t i o n s and "D o m in a n ts" a s D e s ig n a t e d by D r. J . L a u re n s B a r n a r d d u r in g t h e A lla n H ancock F o u n d a tio n S u rv e y o f th e M a in la n d S h e l f . T he n u m b ers a r e t h e V e le r o S t a t i o n N um bers. AMPHIODIA URTICA = AMPHIODIA-PECTINARIA (H a rtm a n , 1966) 4753 4863 5092 5339 5563 5731 5 8 4 2 5975 4757 4871 5098 5 3 5 4 5613 5735 5879 5998 4766 4878 5108 5370 5616 5745 5886 6005 4768 4920 5201 5 3 7 2 5625 5749 5887 6157 4772 4924 5202 5375 5 632 5760 5 8 8 8 6747 4785 4935 5205 5376 5733 5763 5962 4835 4936 5255 5406 5713 5774 5969 4837 5042 5259 5537 5728 5810 5970 4859 50 87 5331 55 3 8 5729 5823 5974 AMPHIODIA-CARDITA 4783 4980 5173 4784 4-981 5174 4820 5160 5258 4824 5168 5260 4828 5169 5271 4951 5171 5325 5567 5856 6007 5 5 6 8 5873 6014 5571 5874 6015 5591 5999 6154 5829 6001 6746 5846 6004 AMPHIODIA-ONUPHIS 4781 5734 4827 5980 5167 5996 5510 6000 5711 ONUPHIS 4786 5775 4877 5869 5163 6002 5732 6131 5746 6132 345 A p p e n d ix T a b le A- 3 ( C o n tin u e d ) AMPHIOPLUS HEXACANTHUS 4722 5617 5750 4764 5628 5772 4769 5654 5971 4775 5741 6103 5045 5743 6104 5111 5744 6744 AMPHIODIA DIGITATA 4760 4767 4776 5162 5762 5960 AMPHIACANTHA AMPHACANTHA 4918 5977 5738 5978 5761 6097 5767 5813 5819 CHLOEI A- PECTINARIA 4747 5868 6013 4851 5870 6133 4855 5871 5086 5872 5747 5997 5828 6003 LISTRIOLOBUS PELODES 4826 5402 5414 6008 5166 5404 5417 6009 5261 5408 5419 6010 5262 5409 5420 6011 5330 5410 5421 5400 5413 5840 A p p e n d ix T a b le A -3 ( C o n tin u e d ) NOTHRIA- TELLINA 4719 4782 4867 5500 5753 5832 5964 6102 4743 4825 4927 5507 5756 5833 5965 6155 4744 4829 4956 5607 5757 5834 5966 6156 4758 4839 5043 5629 5758 5835 5967 6158 4759 4840 5109 5630 5759 5836 5968 6387 4761 4841 5161 5730 5764 5838 5972 4762 4843 5165 5739 5765 5843 5973 4771 4844 5256 5740 5766 5845 6059 4774 4845 5373 5752 5831 5897 6100 NOTHRIA- SPIOPHANE S 4715 5191 5844 4746 5193 5880 4910 5501 5187 5610 5189 5768 5190 5742 DIOPATRA 4720 4869 5631 4721 4922 5709 4777 4938 5808 4787 5172 4819 5564 4822 5614 CHAETOPTERUS 4802 4806 4928 AMYGDALUM PALLIDULUM 5536 5603 5736 5748 347 Appendix Table A-3 (Continued) DENDRASTER EXCENTRICUS 4931 OPHIURA LUTKENI No e x a m p le s OPHIOTHRIX SPICULATA 5751 AMPELISCA 4939 PHERU SA - ONU PHI S 5737 PINNIXA 5263 6101 6107 MACOMA 4984 CAPITELLA 5029 5096 THARYX 4823 5539 - 4886 5754 5027 348 Appendix Table A-3 (Continued) SIPUNCULUS 6099 BRANCHIOSTOMA 4908 4885 SPIOPHANES MISSIONENSIS 4862 5710 5820 STHENELANELLA 5533 NO DOMINANT 4718 4925 5657 5995 4810 5003 5664 6006 4821 5535 5712 6098 4836 5558 5822 6105 4850 5583 5961 6408 4917 5605 5963 6745 349 APPENDIX TABLE A -4 . D ata T a p e R e c o rd Form at w i t h D e s c r i p t i o n o f V a r i a b l e s . V a r i a b l e Number I d e n t i f i c a t i o n o f V a r ia b le v C l) v ( 2) vC3) v ( 4 ) v ( 5 ) v ( 6) v ( 7 ) v ( 8) v ( 9 ) vClO) v ( l l ) v ( 12) v ( 13) v ( 14) v (1 5 ) v ( 1 6 ) v (1 7 ) v (1 8 ) v(19) C ode number o f B i o l o g i c a l e n t r y , i . e . 0001, t h e code n u m b er f o r A c id o s to m a hancocfc'i. S t a t i o n n u m b e r, f o r t h e f i r s t s t a t i o n a t w hich t h i s s p e c i e s o c c u r s ; s u c c e s s i v e ta p e r e c o r d s w i l l c a r r y t h e s t a t i o n n u m b ers, o n e p er r e c o r d , o f a l l s t a t i o n w h e re t h i s s p e c i e s o c c u r s . L a t i t u d e L o n g itu d e D e p th , i n m e t e r s Number o f s p e c im e n s o f vC l) G e a r used T e m p e r a tu r e , w a te r , b o tto m 10 m e te r s S a l i n i t y , w a t e r , b o tto m 10 m e t e r s S am ple v o lu m e , in l i t e r s % g r a v e l % san d % s i l t % c l a y M ed ia n d i a m e t e r in m i l l i m e t e r s S e d im e n t t e m p e r a t u r e S o r t i n g c o e f f i c i e n t % n i t r o g e n , s e d im e n t % c a lc iu m c a r b o n a t e 350 APPENDIX TABLE A-4. (Continued) V a r i a b l e Number I d e n t i f i c a t i o n o f V a r i a b l e v ( 2 0) v ( 21) v ( 2 2) v ( 2 3 ) v ( 2 4 ) v ( 2 5 ) v ( 2 6 ) v ( 2 7 ) v ( 2 8 ) v ( 2 9 ) v ( 3 0 ) P o l y c h a e t e s , w e t w e ig h t C r u s t a c e a n s , w e t w e ig h t E c h in o d e rm s , w e t w e ig h t M o llu s k s , w e t w e ig h t O t h e r s , w e t w e ig h t L j s t r i o l o b u s , w e t w e ig h t A s s o c i a t i o n t y p e , B a r n a r d O xygen, w a t e r , b o tto m 10 m e te r s P h o s p h a te , w a t e r , b o tto m 10 m e te r s S i l i c a t e , w a t e r , b o tto m 10 m e te r s A r e a , g e o g r a p h ic FIRST RECORD E x am p le o f T a p e F o rm a t v ( l ) , 0001 ( f i r s t s p e c i e s ) v ( 2 ) , f i r s t s t a t i o n w i t h f i r s t s p e c i e s v ( 3 ) v ( 4 ) v ( 5 ) SECOND RECORD v ( 3 0 ) v ( l ) , 0001 ( f i r s t s p e c i e s ) v ( 2 ) , s e c o n d s t a t i o n w i t h f i r s t s p e c i e s v ( 3 ) v ( 4 ) v ( 5 ) v(30) APPENDIX TABLE A-4. (Continued) 351 E xam ple o f T ap e F o rm a t THIRD RECORD v ( l ) , 0001 ( f i r s t s p e c i e s ) v ( 2 ) . t h i r d s t a t i o n w i t h f i r s t s p e c i e s v ( 3 ) v ( 4 ) v ( 5 ) v ( 3 0 ) APPENDIX TABLE A- 5 . The r e v i s e d S t r a t i f i e d Sam ple A re a I A rea I I A re a I I I A rea IV 10 F athom 4810 4782 5043 5730 D ep th 4819 4840 5535 5739 C l a s s 4822 4841 5965 55 64 4843 4956 4984 5165 5966 20 F athom 4787 4839 5045 5539 D e p th 4938 5166 5111 5709 C l a s s 5151 5262 5331 5402 5410 5831 5832 5835 5836 5845 5729 5732 30 F athom 4817 4781 4850 5098 D ep th 5563 , 4826 5533 5538 C l a s s I 5999 , 6001 4827 5261 5330 5710 5731 5735 o f 176 A rea V 4806 5754 5027 S a m p le s . Area VI 4718 4720 4885 5501 5740 4719 4721 5741 5742 5743 5751 5752 5844 4722 5087 5744 5750 Area VII 4758 4761 4774 4862 4867 4877 5109 5373 4762 4771 4775 4777 4863 5772 5202 5372 Area VIII 4917 4922 4931 5607 5756 5757 4743 4927 5189 5614 4745 4746 4910 4925 352 APPENDIX TABLE A-5. (Continued) A re a I A re a I I A re a I I I A rea IV 30 F athom D e p th C l a s s ( c o n t . ) 40 F athom 4824 D e p th 5171 C l a s s 5568 5558 5998 6007 50 F athom 4784 D e p th 4820 C l a s s 4821 5160 5 0 -1 0 0 4939 F athom 5996 D e p th C l a s s 50 4 2 5537 5728 5734 5737 5255 5536 5733 5736 4835 5712 4851 5713 5738 5400 5413 5168 5259 5421 5586 5873 4828 4837 4951 5173 5174 4783 4980 5169 5258 5325 5828 A rea V A re a VI A re a V II A re a V I I I 4855 None None 5748 5745 5749 5746 4768 4859 5108 5354 4772 5370 5774 5886 4760 4767 4776 4878 5092 5374 4918 4924 5376 4747 4757 4920 5603 4753 4936 5375 353 APPENDIX TABLE A- 6 The 50 t o p - r a n k e d s p e c i e s i n t h e 176- s a m p le s e t a s r a n k e d b y f r e q u e n c y o f o c c u r r e n c e ( c a p t u r e ) . S p e c ie s n e m e rte a n s unknown ( 0 ) P r i o n o s p i o p i n n a t a (P ) A m phiodia u r t i c a (E) P r i o n o s p i o m a lm g re n i (P ) A ra p h ip h o lis sq u a m a ta (E) P e c t i n a r i a c a l i f o r n i e n s i s P h o lo e g l a b r a (P) G o n iad a b r u n n e a (P) o s t r a c o d s unknow n (C) P a r a o n i s g r a c i l i s (P ) S p io p h a n e s m i s s i o n e n s i s (P) T h a ry x t e s s e l a t a (P ) H a p l o s c o l o p lo s e l o n g a t u s (P) t a n a i d s unknow n ( 0 ) T e r e b e l l i d e s s t r o e m i (P ) A m p e lisc a b r e v i s i m u l a t a (€) H e te ro p h o x u s o c u l a t u s (C) L a o n ic e c i r r a t a (P) S t e r n a s p i s f o s s o r (P ) G ly c e r a c a p i t a t a (P) H a lio p h a sm a g e m in a ta (C) L u m b r in e r is c r u z e n s i s (P) R ank F re q u e n c y P e r c e n t 1 176 1 0 0 .0 2 159 9 0 .4 3 153 8 7 .0 4 149 8 4 .5 5 136 7 7 .3 6 131 7 4 .5 7 124 7 1 .1 8 114 6 4 .8 9 109 6 1 .9 10 108 6 1 .3 11 107 6 0 .8 13 105 5 9 .7 13 105 5 9 .7 13 105 5 9 .7 15 103 5 8 .5 16 101 5 7 .4 17 97 5 5 .0 18 96 5 4 .6 19 95 5 4 .0 20 94 5 3 .3 21 93 5 2 .8 23 92 5 2 .3 355 APPENDIX TABLE A-6 (Continued) S p e c i e s __________________________ A x in o p s id a s e r r i c a t a (M) G n a th ia c r e n u l a t i f r o n s (C ) C o s s u r a C a n d id a (P ) n e m a to d e unknown ( 0 ) G l o t t i d i a a l b i d a ( 0 ) N e p h ty s s p . (P ) A m p e lis c a c r i s t a t a (C ) T e le p s a v u s c o s ta r u m (P ) A x i o t h e l l a r u b r o c i n c t a (P ) S t h e n e la n e 1 1 a u n i f o r m i s (P ) A r i c i d e a s u e c i c a (P ) N e r e i s p r o c e r a (P ) A r i c i d e a l o p e z i (P ) N e p h ty s f e r r u g i n e a (P ) p e le c y p o d s unknown (M) P a ra p h o x u s b i c u s p i d a t u s (C) C a d u lu s s p . (M) P a ra p h o x u s s i m i l i s (C) A m p e lis c a p a c i f i c a (C ) W e s tw o o d illa c a e c u l a (P ) M e ta p h o x u s f r e q u e n s (C ) O xydrom us a r e n i c o l u s (P ) N u c u la n a t a p h r i a (M) Rank : F re q u e n c y P e r c e n t 23 92 5 2 .3 23 92 5 2 .3 26 91 5 1 .7 26 91 5 1 .7 26 91 5 1 .7 28 90 5 1 .2 29 89 5 0 .5 3 0 .5 87 4 9 .4 3 0 .5 87 4 9 .4 3 2 .5 84 4 7 .7 3 2 .5 84 4 7 .7 34 83 4 7 .2 35 80 4 5 .5 37 77 4 3 .8 37 77 4 3 .8 37 77 4 3 .8 40 76 4 3 .2 40 76 4 3 .2 40 76 4 3 .2 42 74 4 2 .0 43 73 4 1 .5 44 72 4 0 .8 4 5 .5 71 4 0 .3 APPENDIX TABLE A-6 (Continued) S p e c i e s ___________________________ R ank______ F r e q u e n c y P e r c e n t P i n n i x a s p . (C) D i a s t y l i d a e unknown (C) C h a e to d e r m a t i n a unknow n (M) A m p e lis c a p u g e t i c a (P ) L e p to s y n a p t a a l b i c a n s (E) 4 5 .5 71 4 0 .3 47 70 3 9 .8 49 69 3 9 .2 49 69 3 9 .2 49 69 3 9 .2 C = C r u s t a c e a n , E = E c h in o d e rm , M = M o llu s k , 0 = O th e r T a x a , P = P o l y c h a e t e 357 APPENDIX TABLE A -7 . The 50 t o p - r a n k e d s p e c i e s i n t h e 1 7 6 - s a m p le s e t a s r a n k e d by p o p u l a t i o n d e n s i t y (s p e c im e n s ,/ s q u a r e m e t e r ) . S p e c i e s R ank D e n s i t y A m p h io d ia u r t i c a (E) 1 3 5 9 .1 o s t r a c o d s unknown (C) 2 2 7 2 .9 A m p h ic te is s c a p h o b r a n c h i a t a (P ) 3 9 3 .9 P r i o n o s p i o m a lm g re n i (P) 4 9 2 .8 brow n o s t r a c o d (C) 5 6 1 .7 T h a ry x m u l t i f i l i s (P ) 6 6 1 .6 A x in o p s id a s e r r i c a t a (M) 7 5 4 . 7 T h a ry x t e s s e l a t a (P ) 8 5 3 . 6 P a r a p h o x u s b i c u s p i d a t u s (C) 9 4 7 . 6 P e c t i n a r i a c a l i f o r n i e n s i s (P) 10 4 5 .3 P r i o n o s p i o p i n n a t a (P ) 11 4 4 . 5 A m p h ip h o lis s q u a m a ta (E) 12 3 9 .5 P h o lo e g l a b r a (P) 13 3 6 .1 L u m b r i n e r is c r u z e n s i s (P) 14 3 5 .9 A m p e lis c a b r e v l s i m u l a t a (€ ) 15 3 5 .7 H a p l o s c o l o p l o s e l o n g a t u s (C) 16 3 1 .7 T e l l i n a b u t t o n ! (M) 17 3 0 .5 A r i c i d e a l o p e z i (P ) 18 2 8 .7 P hraonis g r a c i l i s (P ) 19 2 8 . 6 n e m e r te a n s unknown ( 0 ) 20 2 8 .0 C h l o e i a p i n n a t a (P) 21 2 7 .4 P a r a p h o x u s a b r o n i u s (€ ) 22 2 7 .3 358 APPENDIX TABLE A-7 (Continued) S p e c i e s ______________________________ R a n k ______ D e n s ity n e m a to d e s unknow n ( 0) 23 2 7 .2 t a n a i d s unknown (C) 24 2 6 .3 D o r v i l l e a a r t i c u l a t a (P ) 25 2 5 .7 M ed io raastu s c a l i f o r n i e n s i s (P) 26 2 5 .1 B i t t i u m s u b p la n a tu m (M) 27 2 4 .3 G l o t t i d i a a l b i d a (0 ) 28 2 4 .2 H e te r o p h o x u s o c u l a t t t s (C) 29 2 3 .8 C o s s u r a Candida. (P) 30 2 3 .7 A m p e lis c a c r i s t a t a (C) 31 2 2 .9 S p io p h a n e s m i s s i o n e n s i s 32 2 2 .8 N e p h ty s s p . (P) 33 2 2 .7 P o l y c h a e t e unknown (P) 34 2 2 .5 P h o t i s b r e v i p e s (C) 35 2 1 .4 R o c h e f o r t i a a l e u t i c a (C) 36 1 9 .7 M ag elo n a s a c c u l a t a (P) 37 1 9 .6 C h a e to z o n e c o r o n a (P) 38 1 9 .4 C a r d i t a v e n t r i c o s a (M) 39 1 8 .8 T h a ry x s p . (P) 40 1 8 .5 A d o n to r h in a c y c l i a (M) 41 1 8 .3 M etap h o x u s f r e q u e n s (C) 42 1 8 .0 c a l a n o i d c o p ep o d (C) 43 1 7 .7 G ly c e r a c a p i t a t a (P) 44 1 7 .6 P a ra p h o x u s s i m i l i s (C) 45 1 7 .4 APPENDIX TABLE A-7 (Continued) 359 S p e c i e s ________________________ P a ra p h o x u s e p is to m u s (C) A m p e lis c a m a c r o c e p h a la (G) S t e r n a s p i s f o s s o r (P ) D i a s t y l o p s i s t e n u i s (C) P s e p h i d i a l o r d i (M) C = C r u s t a c e a n , E = E c h in a n d P = P o l y c h a e t e Rank D e n s i ty 46 1 6 .6 47 1 5 -8 48 1 5 .7 49 1 5 .3 50 1 5 .1 rm , M= M o llu s k , 0= O t h e r s , 360 APPENDIX TABLE A -8 - The 50 t o p - r a n k e d s p e c i e s i n t h e 1 7 6 - sa m p le s e t a s r a n k e d b y t h e num ber o f a f f i n i t i e s w i t h o t h e r s p e c i e s o f th e s a m p le s e t . S p e c ie s _______________________* __________ R ank______ A f f i n i t i e s ________ A m p h io d ia u r t i c a (E) 1 88 P r i o n o s p i o p i n n a t a (P) 2 79 n e m e r te a n s unknown ( 0 ) 3 75 P r i o n o s p i o m a lm g re n i (P ) 4 73 P e c t i n a r i a c a l i f o r n i e n s i s (P ) 5 71 A m p h ip h o lis s q u a m a ta (E) 6 69 P h o lo e g l a b r a (P ) 7 65 t a n a i d s unknown (C) 8 56 A m p e lis c a b r e v i s i m u l a t a (C) 9 55 T e r e b e i l i d e s s t r o e m i (P) 10 51 G n a th ia c r e n u l a t i f r o n s (C) 1 1 .5 50 H e te r o p h o x u s o c u l a t u s (C) 1 1 .5 50 G o n iad a b r u n n e a (P) 1 4 .5 48 o s t r a c o d s unknown (C) 1 4 .5 48 P a ra p h o x u s s i m i l i s (C) 1 4 .5 48 A x in o p s id a s e r r i c a t a (M) 1 4 .5 48 A m p e lis c a p a c i f i c a (C) 1 7 .5 47 P a r a o n i s g r a c i l i s (P) 1 7 .5 47 S p io p h a n e s m i s s i o n e n s i s (P ) 1 9 .5 46 P a ra p h o x u s b i c u s p i d a t u s (C) 1 9 .5 46 H a lio p h a s m a g e m in a ta Cc) 2 1 .5 45 G ly c e r a c a p i t a t a (P ) 2 1 .5 45 361 APPENDIX TABLE A-8 (continued) S p e c ie s _________ Rank_______ A f f i n i t i e s M etaphoxus f r e q u e n s (C) 23 41 S t e r n a s p i s f o s s o r (P) 24 41 H a p l o s c o l o p lo s e l o n g a t u s (P) 25 40 D i a s t y l i d a e unknown (C) 27 39 C o s s u r a C andida (P) 27 39 T h a ry x t e s s e l a t a (P) 27 39 L u m b r in e r is c r u z e n s i s (P) 2 9 .5 38 A m p e lisc a p u g e t i c a (C) 2 9 .5 38 S t h e n e l a n e l l a u n i f o r m i s (P) 31 37 G l o t t i d i a a l b i d a (0) 32 36 W e s tw o o d illa c a e c u la (€) 33 34 N ep h ty s f e r r u g i n e a (P) 34 32 A m p e lisc a c r i s t a t a (C) 3 7 ,5 29 L a o n ic e c i r r a t a (P) 3 7 .5 29 A m p e lisc a m a c ro c e p h a la (C) 3 7 .5 29 E u d o r e l l a A (C) 3 7 .5 29 N ic ip p e turaida (C) 41 28 L e p to s y n a p ta a l b i c a n s (E) 41 28 C h a e to d e r m a tin a unknown (M) 41 28 N em ocardium c e n t i f i l o s u m (M) 41 28 A d o n to r h in a c y c l i a (M) 41 28 C h l o e i a p i n n a t a (P) 44 26 T e le p s a v u s c o s ta ru m (P) 46 25 362 APPENDIX TABLE A-8 (Continued) S p e c ie s _________________________________ Rank_________A f f i n i t i e s N e p h ty s s p . (P) 46 25 n em atode unknown (0) 46 25 A r i c i d e a l o p e z i (P) 48 23 Compsomyax s u b d ia p h a h a (M) 49 21 T e l l i n a b u t t o n i (M) 50 20 C = C r u s t a c e a n , E = E c h in o d e rm , M = M o llu s k , 0 = O th e r T a x a , P = P o l y c h a e t e 5 APPENDIX B ALLAN HANCOCK FOUNDATION SURVEY METHODS OF SAMPLING AND ANALYSIS T h is a p p e n d ix i n c l u d e s a d e t a i l e d d e s c r i p t i o n o f th e m ethods o f s a m p lin g and a n a l y s i s em ployed i n t h e A lla n Hancock F o u n d a tio n s u rv e y o f th e s o u t h e r n C a l i f o r n i a n m ain lan d s h e l f . B i o l o g i c a l M ethods The m eth o d s u t i l i z e d to sam ple and a n a ly z e th e b e n t h i c m a c ro fa u n a d u r in g th e A l l a n Hancock F o u n d a tio n S u rv ey o f th e m a in la n d s h e l f a r e d e s c r i b e d e l s e w h e r e i n th e l i t e r a t u r e ( B a r n a r d , H artm an and J o n e s , 1959; B a r n a r d and J o n e s , 1960; Durham, 1955; G. J o n e s [ a ] , i n S te v e n s o n , 1961; and i n AHFtUSC, 1 9 6 5 ), b u t a s i n g l e c o r r e c t and com p l e t e a c c o u n t i s l a c k i n g . B i o l o g i c a l S am pling E quipm ent and S am pling M ethods Two b i o l o g i c a l sa m p lin g d e v i c e s w ere em ployed i n t h i s s u r v e y : a m o d ifie d Hayward s ta n d a rd , o r a n g e - p e e l b u c k e t (= OPB), and a m o d ifie d l / l O s q u a r e m e te r Van Veen g r a b . 363 364 The f A r s t s a m p le r was o p e r a t e d fro m t h e R/V V e le r o IV An w a t e r d e p th s i n e x c e s s o f 10 m e t e r s . The Van Veen was u sed fro m th e m o to r la u n c h o f t h e s h i p t o sam ple t h e s h a llo w n e a r s h o r e p o r t i o n o f th e s h e l f i n d e p th s o f l e s s th a n 10 m e t e r s . The Hayward s t a n d a r d OPB u s e d ab o ard t h e s h ip h a s a r a t e d c a p a c i t y o f 2 c u b ic f e e t ( 5 6 .6 l i t e r s ) and sa m p le s an a r e a o f 2 - 3 / 5 s q u a r e f e e t ( c a . 0 . 2 5 s q u a re m e t e r s ) . Durham (1955; pp. 1 5 2 -1 5 3 ) d e s c r i b e s i n d e t a i l th e m o d if ie d OPB and i t s method o f o p e r a t i o n . H is o r i g i n a l d e s c r i p t i o n i s t h e most a c c u r a t e and a u t h o r i t a t i v e a c c o u n t g iv e n i n th e l i t e r a t u r e , b u t t h i s i n s t r u m e n t i s a l s o d e s c r i b e d by Hop k i n s (1 9 6 4 ), by G. J o n e s ( t a l , in S te v e n s o n , 1961 and i n AHF:USC ( 1 9 6 5 ). I l l u s t r a t i o n s o f t h e m o d ifie d OPB u s e d i n t h e s u rv e y a r e i n H artm an (1 9 5 5 ; P l a t e s 3 -5 , F i g u r e s 5 - 8 , 1 0 - 1 3 ) , Holme (1 9 6 4 , F ig u r e 2 3 ) , P h l e g e r (1960, F ig u r e 7 ) , G. J o n e s ( [ a ] , in S te v e n s o n , 1961, F i g u r e s 3 - 5 ) , and i n AHF:USC (1 9 6 5 , F ig u r e 1 .2 ) (A ppendix F ig u re B - l b , c, d ) . . . . The b u c k e t i s m o d if ie d by a c a n v a s hood o v er t h e open s t r u c t u r e , t o p r e v e n t th e w a sh in g o u t o f th e b o tto m sam p le a s t h e b u c k e t i s h a u l e d up th ro u g h t h e w a t e r . The hood h a s tw e lv e f o u r - i n c h by s i x - i n c h o v a l v e n t s , e a c h b e a r i n g a f l a p on th e o u t s i d e , h in g e d a t th e t o p t o a l l o w th e e s c a p e o f w a te r a s th e b u c k e t i s r a i s e d . B ecause o f th e h o o d , th e b u c k e t w i l l b r i n g t o t h e s u r f a c e a lm o s t d o u b le i t s r a t e d c a p a c i t y o f s o f t mud. The b u c k e t i s f u r t h e r m o d if ie d w i t h a lo w e r in g p e n d a n t w h ic h a u t o m a t i c a l l y t r i p s t h e b u c k e t when i t s t r i k e s th e b o tto m , and a llo w s i t s o p e r a t i o n on a s i n g l e 7 /1 6 in c h s t e e l c a b le wound on a v a r i a b l e - s p e e d w inch APPENDIX FIGURE B-l B - l a M o d ifie d 1./10 S q u a re M e te r Van Veen Grab Shown w i t h Jaws Open (U pper L e f t ) ( F ig u r e 8 , J o n e s [ a ] , i n S te v e n s o n , 1961; and i n F ig u r e 1 . 4 , AHF:USC, 1 9 6 5 ). B - l b Hayward S ta n d a r d O r a n g e -P e e l B u c k e t (Open) (Lower L e f t ) ( F ig u r e 5 , J o n e s [a], i n S te v e n s o n , 1961; and i n F i g u r e 1 . 2 , AHFtUSC, 1965; c o u r t e s y o f Dr. O lga H artm an, AHF). B - l c Hayward S ta n d a r d O r a n g e -P e e l B u c k e t (Open on d eck show ing t r i p m echanism ) (Upper R ig h t) ( F ig u r e 5, P l a t e 3, H artm an , 1955; F ig u re 3, J o n e s [a], i n S te v e n s o n , 1961; and i n F ig u r e 1 . 2 , AHF:USC, 1965; c o u r t e s y o f D r. Olga H artm an, AHF). B - l d Hayward S t a n d a r d O r a n g e -P e e l B u c k e t (C lo s e d ) ( F ig u r e 11, P l a t e 4, H artm an, 1955; F i g u r e 4, J o n e s [a], i n S te v e n s o n , 1961; and i n F i g u r e 1 .2 , AHF:USC, 1965, c o u r t e s y o f D r. Olga H artm an, AHF). 365 366 Figure B-l 367 mounted on th e w o rk in g d e c k . . . . H a u lin g on th e c a b l e c l o s e s th e f o u r jaw s o f t h e t r i p p e d b u c k e t . (Durham, 1955, p . 152) The Van Veen g ra b h a s been i l l u s t r a t e d and d e s c r i b e d i n t h r e e r e c e n t a r t i c l e s on m a rin e c o l l e c t i n g d e v i c e s (H e d g p e th , 1957, F ig u re 4; Holme, 1964, F i g u r e s 13, 18; H o p k in s, 1964, F ig u r e 4 ) . I t s d i g g i n g c h a r a c t e r i s t i c s a re d i s c u s s e d by G a l l a r d o (1 9 6 5 ) and L ie and Pamatmat ( 1 9 6 5 ) . The m o d ifie d l / l O ms Van Veen g rab u t i l i z e d i n t h i s i n v e s t i g a t i o n had a maximum c a p a c i t y o f 2 4 .7 1 . I t was d e l i b e r a t e l y c o n s t r u c t e d o f t h i n s h e e t s t e e l so t h a t i t s h o u ld be l i g h t enough t o u se by hand from a d a v i t on th e s t e r n o f a m otor la u n c h . L arge t e e t h w ere added to t h e b i t i n g edge o f each ja w , 4 on one s i d e and 5 on th e o t h e r ; t h e t e e t h e x te n d e d w e l l beyond th e c u t t i n g e d g e , b u t i n no way i n t e r f e r e d w ith t h e c l o s i n g o f th e g r a b . The t e e t h a s s i s t e d i n " s e t t i n g t h e b i t e " i n t h e i n i t i a l c o n t a c t o f th e g ra b w i t h th e s u b s t r a t e . The m o d ifie d Van Veen g ra b u se d i n th e AHF s u rv e y a p p e a r s i n G. J o n e s ( [ a ] , i n S te v e n s o n , 1961, F i g u r e s 8 -1 0 ) and i n AHF:USC (1 9 6 5 , F ig u r e 1 .4 ) (Ap p e n d ix F ig u re B - l a ) . The sa m p lin g o p e r a t i o n s and t h e s h ip b o a r d s c r e e n i n g o f th e b o tto m sam p les u sed i n t h i s i n v e s t i g a t i o n d i f f e r e d - l i t t l e from th e p r o c e d u r e s i n i t i a l l y d e s c r i b e d by Durham ( 1 9 5 5 ). These a re a l s o p r e s e n t e d by B a rn a rd and J o n e s ( 1 9 6 0 ), by G. J o n e s ( [ a ] , i n S te v e n s o n , 1961) and in AHF:USC ( 1 9 6 5 ) . The d i s c u s s i o n t h a t f o ll o w s i s b a s e d on t h e s e s o u r c e s . The open s a m p le r i s l i f t e d o f f t h e deck and moved a f t u n t i l i t c l e a r s t h e s t e r n o f t h e v e s s e l by means o f a p n e u m a t i c a l l y o p e r a t e d nA,T fra m e . The g r a b i s lo w e re d w ith th e w in c h i n h ig h g e a r a t a r a t e o f a p p r o x im a te ly 40 f a t h o m s/m in u te ( - 73 m / m i n u t e ) . A ta c h o m e te r on th e w in ch i n d i c a t e s th e l e n g t h o f w ir e t h a t h a s unwound from th e r e e l and t h u s i n d i c a t e s t h e a p p ro x im a te d e p th o f b o tto m f ro m w hich th e sam ple i s c o l l e c t e d . A more a c c u r a t e m easu re o f d e p th o f c a p t u r e i s p r o v id e d by th e s h i p ’ s f a t h o m e t e r . The g ra b c l o s e s when th e drum r o t a t i o n i s r e v e r s e d and one s t a r t s t o r a i s e t h e c a b l e . The g r a b u s u a l l y i s h a u le d t o th e s u r f a c e a t t h e same sp e e d a t w h ich i t was lo w e re d , b u t w inch sp e e d i s slo w ed a s i t r e a c h e s t h e s u r f a c e . The "A” fram e i s moved f o rw a r d t o b r i n g th e g r a b a b o a rd ; th e g r a b i s lo w e re d o v er a s u i t a b l e tu b t o c o l l e c t th e sam ple ( H a r t man, 1955, P l a t e 4 , F i g u r e s 9, 12, and P l a t e 5, F ig u r e 13; Holme, 1964, F i g u r e 3 0 ) . A h e a v y c y l i n d r i c a l tu b w i t h a c a p a c i t y o f 4 .4 6 c u b ic f e e t (1 2 6 .2 1 ) i s u s e d w ith th e OPB. The OPB i s opened and e m p tie d a u t o m a t i c a l l y when, a f t e r a s i n g l e c h a in ( a t t a c h e d t o th e ,!An fra m e ) i s hooked i n t o an eye on t h e u p p e r p o r t i o n o f t h e g r a b , t h e w in ch c a b le i s s la c k e n e d so t h a t t h e c h a i n b e a r s t h e e n t i r e w eig h t o f t h e g ra b and sam ple. F ra g m e n ts r e m a in in g i n t h e g ra b a r e h o s e d - o u t o r th e y w ash o u t a s th e s a m p le r d e sc e n d s f o r a n o t h e r sa m p le . When s t i c k y mud i s b e i n g c o l l e c t e d , i t i s 369 n e c e s s a r y t o do some c l e a n i n g o f th e b a c k e t by han d ; t h i s i s p a r t i c u l a r l y t r u e o f th e OPB. The t u b c o n t a i n i n g t h e sam ple i s c a r r i e d t o th e s c r e e n i n g a r e a . The volum e o f t h e sam ple i s d e te r m in e d by means o f a c a l i b r a t e d b r a s s r u l e . In m o st c a s e s t h e s u r f a c e o f th e sam p le i n t h e tu b m ust be sm oothed to e n s u r e a r e a s o n a b l y a c c u r a t e m e a su re m e n t. The v a l u e s d e te r m in e d by t h i s r u l e a r e d i r e c t l y c o n v e r t e d i n t o c u b ic f e e t o r l i t e r s u s i n g a c o n v e r s i o n t a b l e c a l c u l a t e d f o r t h e s e two t u b s . S c r e e n i n g o f t h e sa m p le , th e s e p a r a t i o n o f t h e b i o l o g i c a l sp e c im e n s from th e s e d im e n t s , i s a c c o m p lis h e d by a f lo w o f s e a w a t e r t h r o u g h a s e r i e s o f g r a d e d s i e v e s m ount ed i n a m e c h a n ic a l s h a k e r (H artm an, 1955, P l a t e 5, F i g u r e s 1 4 -1 6 ; Holme, 1964, F i g u r e 33; G. J o n e s [a], i n S te v e n s o n , 1961, F i g u r e s 6 , 7; and i n AHF:USC, 1965, F ig u r e 1 .3 ) (A ppendix F ig u r e B - 2 ) . The p r o c e s s i s f a c i l i t a t e d by a s p r a y o f s a l t w a te r fro m s i x s p r i n k l e r h e a d s ( s h o w e r - ty p e ) m ounted on an o v e r -h e a d fram e above th e s i e v e s . In a d d i t i o n , w a te r fro m a 1- i n c h h o se may be u s e d by th e o p e r a t o r i n a d i r e c t e d manner t o s o f t e n t h e more r e s i s t a n t p o r t i o n s o f t h e sam p le. H o r i z o n t a l a g i t a t i o n o f t h e s i e v e s g r e a t l y a c c e l e r a t e s sam ple p r o c e s s i n g . The s i e v e s a r e h e l d by a c a r r i e r . The s i e v e c a r r i e r i s m ounted on f o u r s m a ll s t e e l w h e e ls on a s h o r t t r a c k and i s moved a t a r a t e o f 400 tim e s / m i n u t e o v er a d i s t a n c e o f a p p r o x i m a te ly 7 /1 6 o f a n i n c h (=11 mm). APPENDIX FIGURE B-2 B~2a M e c h a n ic a l S h a k e r w i t h G raded S c r e e n s Aboard th e R./V V e le ro IV Viewed fro m t h e S id e' (U pper P h o to g ra p h ) ( F ig u r e 6, J o n e s [a], i n S te v e n s o n , 1961; c o u r t e s y o f D r, O lga H artm an, AHF). B -2b M e c h a n ic a l S h a k e r w i t h G raded S c re e n s Viewed from Above (Lower P h o to g ra p h ) ( F ig u r e 16, P l a t e 5, H artm an, 1955; F ig u r e 7 , J o n e s [ a] , i n S te v e n s o n , 1961; c o u r t e s y o f D r. O lg a H artm an, AHF). 370 372 The c a r r i e r i s d r i v e n by power s u p p l i e d by a s m a l l e l e c t r i c m otor d i r e c t l y th r o u g h an a d j u s t a b l e e c c e n t r i c . S i e v e s o f t h r e e d i f f e r e n t s i z e s may be p la c e d i n th e c a r r i e r . The t o p s i e v e I s c o n s t r u c t e d o f % -in ch d i a mond mesh s t e e l s c r e e n ; th e se c o n d s i e v e i s made o f 12-o p e n i n g s / i n c h s q u a r e mesh b r a s s s c r e e n ; t h e t h i r d and b o tto m s i e v e i s t h e f i n e s t w i t h 2 4 -m e sh ./in c h . The l a s t s c r e e n d e te r m in e d t h e minimum s i z e o f t h e sp e c im e n s c o l l e c t e d i n t h i s s u rv e y . The s q u a r e o p e n in g s m ea su re d 0 .7 mm on th e d i a g o n a l . To p r e v e n t th e l o s s o f a p a r t o f th e sam ple a s a r e s u l t o f s p l a s h i n g o r s l o p p i n g when t h e s h ip r o l l s , th e b o tto m s c r e e n i s p r o v id e d w i t h s i d e s 3 in c h e s (= 7 . 6 cm) h i g h . The c a r r i e r , s c r e e n s , c a r r i e r t r a c k , e l e c t r i c m otor and fram e s u p p o r t i n g t h e s p r i n k l e r h e a d s a r e m ounted on a s t e e l s t a n d . G. J o n e s ( [ a ] , i n S te v e n s o n , 11961) d e s c r i b e d t h e s h ip b o a r d sa m p le p r o c e s s i n g t e c h n i q u e s i n d e t a i l ; h i s d i s c u s s i o n i s r e p e a t e d i n r e v i s e d fo rm i n AHF:DSC (1 9 6 5 ); B a rn a rd and J o n e s (1960) a l s o o u t l i n e t h e s e m eth o d s. De p e n d in g on t h e s i z e o f th e sam ple and t h e n a t u r e o f th e s u b s t r a t e , th e tu b c o n t e n t s a r e e i t h e r dumped d i r e c t l y I n t o th e s i e v e s ( s m a l l s a m p le s ) o r s h o v e le d i n t o t h e s i e v e s ( l a r g e s a m p l e s ) . The r a t e a t w hich sa m p le s may be w ashed i s a f u n c t i o n o f th e s e d im e n t c h a r a c t e r . S t i c k y m a rin e muds c o n t a i n i n g a h i g h c l a y c o n t e n t w ash s lo w ly . Such sam p les 373 m u st be added t o th e s c r e e n s s lo w ly t o a v o id o v e r l o a d i n g an d f l o o d i n g . Only t h e b o tto m s i e v e i s n e e d e d to w ash most s a m p le s ; th e c o a r s e - m e s h s c r e e n s a r e needed when s u b s t r a t e s t h a t c o n t a i n a h i g h p e r c e n t a g e o f c o a r s e m a t e r i a l a r e p r o c e s s e d . C a re m ust be t a k e n in th e s c r e e n i n g p r o c e s s t o a- v o i d damage t o th e s p e c im e n s by h a r s h s p r a y i n g w ith t h e w a sh in g w a t e r . I t i s a d v i s a b l e n o t t o wash a l l of t h e s e d im e n t th r o u g h th e s i e v e , f o r a s m a l l amount o f s e d im e n t r e t a i n e d on t h e s c r e e n w i l l s e rv e a s p r o t e c t i o n f o r t h e s m a l l , d e l i c a t e s p e c im e n s . When s c r e e n i n g i s c o m p le te , the sp ecim e n s and d e b r i s a r e c o l l e c t e d and p l a c e d i n s u i t a b l e j a r s . The l a r g e sp e c im e n s may be g a t h e r e d b y f o r c e p s ; the s m a l l e r o rg a n ism s and d e b r i s a re s w e p t to a c o r n e r o f th e s i e v e w i t h a d i r e c t e d s tr e a m o f w a t e r and p i c k e d up w i t h a l a r g e s p a t u l a . P r e s e r v a t i v e , 10 p e r cen t s e a w ater f o r m a l i n , I s added t o e a c h sp ecim en j a r . T h e use o f u n b u f f e r e d f o r m a l i n was somewhat i n j u r i o u s t o t h e t e s t s o f s m a ll m o llu s k s and to t h e c a l c a r e o u s s k e l e t o n s of e c h i n o - d erm s, p a r t i c u l a r l y t h e s m a ll s p i c u l e s of t h e h o l o t h u r i a n s . A f t e r e a c h sam ple was s c r e e n e d , t h e s ie v e s w e re rem oved fro m t h e c a r r i e r and c a r e f u l l y c l e a n e d w ith a hose; j e t s of w a te r fro m t h e h o se w ere d i r e c t e d a g a i n s t t h e under s u r f a c e , A s im p le m ethod o f s t a t i o n e n u m e r a tio n and l a b e l i n g was em ployed i n t h i s s u r v e y . A s i n g l e num ber, the s t a t i o n 374 num ber, was u s e d t o i d e n t i f y a l l s p e c im e n s , sp e c im e n j a r s , g e o l o g i c a l s a m p le s , h y d r o g r a p h i c s a m p le s , e t c . , c o l l e c t e d a t a p a r t i c u l a r s t a t i o n . The s t a t i o n num bers a r e a c o n t i n u ous c h r o n o l o g i c a l s e r i e s , w i t h a number f o r e a c h " s t o p " o r u n i t o f w ork done by t h e r e s e a r c h v e s s e l . S t a t i o n num bers w ere w r i t t e n on m a sk in g ta p e l a b e l s f i r m l y a f f i x e d t o t h e s p e c im e n j a r s and j a r l i d s . S t a t i o n r e c o r d s w ere k e p t on t h e b r i d g e and t h e w o rk in g d e c k . The f o l l o w i n g i t e m s w ere r e c o r d e d f o r e a c h b i o l o g i c a l s t a t i o n on th e ’’S t a t i o n R e c o rd S h e e t s ” k e p t on t h e w o rk in g d e c k : c r u i s e num ber, d a t e , s t a t i o n num ber, tim e o f a r r i v a l , s o n i c d e p t h i n f e e t ( d e t e r m i n e d by P r e c i s i o n D ep th R e c o r d e r ) , tim e o f l e a v i n g , g e n e r a l l o c a t i o n , d e s c r i p t i o n o f t h e sa m p le b e f o r e w a s h in g , d e s c r i p t i o n o f t h e sam ple a f t e r w a s h in g , t e m p e r a t u r e o f th e s e d im e n t , volum e o f t h e s a m p le , w ir e d e p t h , and any b i o l o g i c a l re m a rk s r e g a r d i n g t h e n a t u r e o f t h e f a u n a . E xam ples o f t h e " S t a t i o n R e c o rd S h e e t s ” a r e i n c l u d e d i n B a r n a r d an d J o n e s (1960) and G. J o n e s [ a ] , S t e v e n s o n , 1961) (A p p en d ix T a b le B - l ) . The s a m p lin g o p e r a t i o n s a b o a rd t h e m o to r l a u n c h u t i l i z i n g th e m a n u a lly o p e r a t e d 1./10 m2 Van Veen g ra b v a r i e d som ew hat fro m t h e t e c h n i q u e s em ployed w i t h th e l a r g e r s a m p le r . When a sam p le was o b t a i n e d , t h e g r a b was l i f t ed i n t o a b o x t h a t e x te n d e d o u t o v e r t h e w a t e r a t t h e s t e r n o f th e l a u n c h . The sam p le was rem oved d i r e c t l y i n t o g a l l o n j a r s . The g r a b was w ashed o u t i n t o th e b o x ; a s c r e e n 375 APPENDIX TABLE B-l STATION RECORD SHEET C r u i s e No.__________ D ate S t a t i o n No.__________ _ Time A r .________ _Depth__________ f t . Time Lv. Depth________f t . G e n e r a l L o c a t i o n ______________________________________________________ S ea: D i r e c t i o n _________P e r i o d __________se c . H t . __________f t . S w e ll: D i r e c t i o n _________P e r i o d s e c . H t . __________f t . W ater T :ran sp aren cy ____________ f t . W ater C o l o r __________________ R e m a rk s: W a te r S am ples__________________________ D e p th A p p a r a tu s Temp. S a l. O2 NH3 PO^ S i 02 " pH O r a n g e -P e e l B otto m S a m p le r: Sed. d e s c r . b e f o r e w ash___________________________________ S ed. d e s c r . a f t e r w ash ___________________ _______________ Temp, o f se d im e n t__________ Volume: S c a le ________J ^ rt:ie_ S o n ic d e p t h ___________f t . Wire d e p t h _________f t . B i o l , re m a rk s P l a n k t o n H a u l (Nansen B o t t l e ) : D ep th i n t e r v a l s ______________ Remarks 376 APPENDIX TABLE B-l (Continued) S n a p p e r Sam ple: D e s c r i p t i o n _________ S o n ic d e p th _________ H2S_____________ O il C o r in g Tube: T ype o f t u b e _________ S o n ic d . ____________ f t . W ire d .____f t . L e n g th o f c o r e f t . D e p th o f p e n e t r . f t . L e n g th s o f s a m p le s _________________________________________________ D e s c r i p t i o n _________________________________________________________ f t . W ire d e p t h ___________J f t . Gvl Rx 377 (0 .4 9 5 mesh.) i n t h e b o tto m o f th e box r e t a i n e d th e fe w r e m a in in g sp e c im e n s t h a t m ig h t have b e e n m is s e d . Thus* th e sam p les c o l l e c t e d by th e Van Veen g r a b a b o a rd th e la u n c h were p r e s e r v e d v i r t u a l l y u n s c re e n e d . S c r e e n i n g was com p l e t e d l a t e r , e i t h e r a b o a rd t h e s h i p o r i n t h e l a b o r a t o r y . The l a b e l i n g p r o c e d u r e and r e c o r d s k e p t on t h e l a u n c h were s i m i l a r t o t h o s e em ployed a b o a rd t h e V e le r o IV (G. J o n e s [ al , i n S te v e n s o n , 1 9 6 1 ). B i o l o g i c a l L a b o r a t o r y M ethods The t r e a t m e n t a c c o r d e d b e n t h i c sam p les c o l l e c t e d d u r in g t h e A l l a n H ancock F o u n d a tio n s u r v e y i s d e s c r i b e d by B a rn a rd an d J o n e s (1960) and G. J o n e s ( [ a ] , i n S te v e n s o n , 1961); t h e l a t t e r a c c o u n t, a l s o r e p e a t e d i n AHF:USC (1 9 6 5 ), i s f o ll o w e d h e r e : ( 1) w a sh in g was c o m p le te d ; sa m p le s w ere washed th r o u g h a 32-m esh p e r in c h T y l e r s c r e e n ( o p e n in g s o f 0 .4 9 5 mm) t o remove th e r e m a in in g f i n e s e d im e n t; w i t h c o a r s e sa n d s a m p le s , w a te r f l o t a t i o n was em ployed; (2 ) th e a n im a ls g r e a t e r t h a n 3 mm i n l e a s t d im e n s io n w ere s e g r e g a t ed i n t o p h y l o g e n e t i c g ro u p s and th e s t a n d i n g c ro p was d e te r m in e d a s gram s o f w et d r a i n e d a n im a ls p r e s e r v e d i n f o r m a l i n ( t h e m ethod o f T h o rs o n , 1957; m o llu s k s w ere w eig h ed w i t h s h e l l s , worms w i t h o u t t u b e s , e t c . ) ; th e a n i m als w ere s t o r e d i n 70 p e r c e n t i s o p r o p a n o l ; (3) th e l a r g e s t and m o st c o n s p ic u o u s s p e c i e s w ere d e te r m in e d ; (4) th e f l o c c u l e n t m a t e r i a l s c o n t a i n i n g m i c r o s c o p i c a n im a ls w ere 378 s t o r e d i n 70 p e r c e n t i s o p r o p a n o l ; g e n e r a l l y t h i s m a t e r i a l c o n t a i n e d l e s s th a n 5 p e r c e n t o f th e s t a n d i n g c r o p ; t h i s m a t e r i a l was s o r t e d w i t h a b i n o c u l a r s t e r e o - m i c r o s c o p e ; a s a m p le was c o n s id e r e d " c o m p l e t e l y s o r t e d " when a l l o f t h e m eta z o a n a n im a ls l a r g e r th a n 1 .0 mm w ere rem oved; (5) th e r e s i d u a l p o r t i o n was d r i e d and s t o r e d . S p e c i f i c d e t e r m i n a t i o n s o f th e a n im a ls o f t h e s e sa m p le s w ere made by t h e f o l l o w i n g s c i e n t i s t s o f th e A l l a n H ancock F o u n d a tio n : D r. O lg a H artm an, p o l y c h a e t o u s a n n e l i d s ; D r. J . L a u re n s B a r n a r d (now w i t h th e U. S. N a t i o n a l Museum), c r u s t a c e a n s e x c e p t i n g cum aceans; Mr. R o b e r t R. G iven, cum aceans; C a p t a i n F r e d C. Z ie s e n h e n n e , e c h in o d e rm s ; and th e a u t h o r , m o l l u s k s . C a r e f u l r e c o r d s w ere k e p t f o r e a c h sam ple d u r i n g a l l o f t h e p h a s e s o f th e a n a l y t i c a l p r o c e s s on d a t a s h e e t s d e s ig n e d f o r t h i s s u r v e y . E xam ples o f th e "OPB Sample A n a l y s i s " s h e e t s a r e i n c l u d e d i n B a rn a rd and J o n e s (1960) an d G. J o n e s ( [a ], i n S te v e n so n , 1961) (A ppendix T a b le B - 2 ) . 379 APPENDIX TABLE B-2 LABORATORY RECORD SHEETS (C o n d e n se d : d o a b le l i n e i n d i c a t e s end o f page) OPG SAMPLE ANALYSIS D ate__________________ S t a t i o n ____ _ L o c a t i o n _____________ Time L a t i t u d e ____________________________ L o n g itu d e D ep th_________________fm s. f t - me t e r s S e d im e n t t y p e _______________________________________________________ S e d im e n t t e m p e r a t u r e _________________ 'C S c r e e n i n g s __________________________________________________________ Rem arks WET WEIGHTS: POLYCHAETA g g,/m2 CRUSTACEA g g,/m2 OPHIUROIDEA g g,/m2 MOLLUSCA g g/m2 ECHIUROIDEA g g/m 2 HOLOTHURIOIDEA g g,/m2 2 T o t a l W eight ____________g g/m 380 APPENDIX TABLE B-2 (Continued) POLYCSAETA: c o m p le te ly s o r t e d S t a t i o n ( y e s /n o ) TOTAL W eight TOTAL CRUSTACEA: c o m p le te ly s o r t e d S t a t i o n ( y e s /n o ) Amphipoda C a p r e l l i d e a C i r r i p e d i a 381 ■ APPENDIX TABLE B-2 (C o n tin u e d ) Copepoda ______________ Cumacea D ecapoda Iso p o d a N e b a l i a c e a 382 APPENDIX TABLE B-2 (Continued) O s t r a c o d a T a n a i d a c e a TOTAL W eight ______________ TOTAL _ c o m p l e t e l y s o r t e d __________ S t a t i o n ( y e s / n o ) C r i n o i d e a ECHINODERMATA: A s t e r o i d e a 383 APPENDIX TABLE B-2 (C o n tin u e d ) E c h in o id e a H o l o t h u r i o i d e a O p h iu r o id e a TOTAL W eight ____________ TOTAL MOLLUSCA: c o m p le te ly s o r t e d S t a t i o n (y e s',/ no) A m phineura 384 APPENDIX TABLE B-2 (C o n tin u e d ; C e p h a lo p o d a ______________ G a s tro p o d a P e le c y p o d a Scaphopoda TOTAL W eight TOTAL 385 APPENDIX TABLE B-2 (Continued) OTHER GROUPS: c o m p le te ly s o r t e d S t a t i o n ^ (yes/no.) TOTAL W eight __________ TOTAL S t a t i o n L a r g e s t A n im a l(s ) : C o n s p ic u o u s s p e c i e s (o r g r o u p ) : S p e c i e s Per* c e n t S pecim ens P e r c e n t POLYCHAETA CRUSTACEA ECHINODERMATA MOLLUSCA OTHER GROUPS TOTAL SUMMARY: TOTAL RESIDUAL wgt. v o l . E n v ir o n m e n ta l S am p lin g M ethods and A n a l y s i s The n a t u r e o f th e p h y s i c a l e n v iro n m e n t was i n v e s t i g a te d by m easu rem en t o f c e r t a i n g e o l o g i c a l and h y d r o g r a p h ic v a r i a b l e s a t m o st o f th e l o c a l i t i e s w here t h e b e n t h i c m a c ro fa u n a was s a m p le d . The m eth o d s u t i l i z e d t o s tu d y t h e p h y s i c a l e n v iro n m e n t a r e d e s c r i b e d by T ib b y ( i n S te v e n s o n , 1 9 6 1 ), W iraberley ( i n S te v e n s o n , 1 9 6 1 ), W im berley (1 9 6 4 ), U chupi ( i n S te v e n s o n , 1961) and AHF:USC ( 1 9 6 5 ). T hese s o u r c e s s e r v e as a b a s i s f o r th e f o l l o w i n g d i s c u s s i o n . G e o l o g i c a l S a m p lin g M ethods a n d A n a l y s i s W im berley ( i n S te v e n s o n , 1961; and 1964) d e s c r i b e s th e m e th o d s u s e d t o sam ple and a n a l y z e t h e p h y s i c a l p r o p e r t i e s o f t h e s e d im e n ts ; h i s d e s c r i p t i o n i s r e p e a t e d i n AHFrUSC (1 9 6 5 ). S ed im en t s a m p le s were c o l l e c t e d w i t h t h e Hayward s t a n d a r d o r a n g e - p e e l b u c k e t (OPB). T h i s i n s t r u m e n t i s d e s c r i b e d i n d e t a i l i n t h i s a p p e n d ix i n th e s e c t i o n e n t i t l e d t h e " B i o l o g i c a l S am p lin g E q u ip m en t and S am pling M e th o d s ." B e f o r e s c r e e n i n g , a p p r o x i m a te ly one p i n t (= ,2.1 l i t e r s ) o f s e d im e n t was rem oved fro m t h e sam ple tu b and p l a c e d i n an unwaxed c y l i n d r i c a l p a p e r c o n t a i n e r , l i k e th o s e i n w h ich i c e cream i s s o l d . C o n t a i n e r s w ere l a b e l e d w ith t h e s t a t i o n num ber. A f i e l d d e s c r i p t i o n o f th e s e d i ment t e x t u r e an d c o l o r was r e c o r d e d on t h e " S t a t i o n R e c o rd 387 Sheet1 ’ (see Appendix Table B-l) . S e d im e n t t e m p e r a t u r e s w ere m e a s u re d w i t h an o r d i n a r y l a b o r a t o r y th e rm o m e te r ( a c c u r a c y o f 0 .1 ° C ) by t h r u s t i n g i t i n t o t h e s e d im e n t sa m p le i m m e d ia te ly a f t e r i t was rem oved fro m t h e g r a b and p l a c e d i n t o t h e d e c k t u b . Be c a u s e o f t h e l a r g e volum e o f m o st s a m p le s , th e r a p i d a s c e n t o f t h e g r a b fro m r e l a t i v e l y s h a l l o w d e p t h s , and t h e r a t h e r low t h e r m a l c o n d u c t i v i t y o f t h e s e d im e n ts ( e x c l u d i n g s a n d s f o r w h ic h no m e a su re m e n ts w ere m a d e ) , t h i s m ethod p r o v i d e s a f a i r l y a c c u r a t e i n d i r e c t m e a s u re o f s e d im e n t t e m p e r a t u r e ( J o n e s and B a r n a r d , 1 9 6 3 ). S am p les had u s u a l l y t h r o u g h l y d r i e d by t h e tim e th e y w e re a n a ly z e d i n t h e l a b o r a t o r y ; i f n o t , d r y i n g was c o m p le te d i n an o v en . S am ples w ere s p l i t u s i n g a J o n e s Sample S p l i t t e r (K rum bein an d P e t t i j o h n , 1938; F i g u r e 8 ) and a p o r t i o n o f e a c h was s e t a s i d e f o r c h e m ic a l a n a l y s i s . The p o r t i o n o f th e sa m p le t o be u s e d f o r t e x t u r a l a n a l y s i s was w e ig h e d . P r e p a r a t i o n s f o r t e x t u r a l a n a l y s i s e n t a i l e d ( 1) s o a k i n g e a c h sam p le i n w a t e r t o d i s a g g r e g a t e th e s e d i m en t, and ( 2 ) w e t - s c r e e n i n g i t t h r o u g h a 0 .0 6 2 ram s i e v e t o s e p a r a t e t h e ’’c o a r s e ” f r a c t i o n fro m t h e ’’f i n e ” f r a c t i o n . The c o a r s e f r a c t i o n was d r i e d an d w e ig h e d ; th e p e r c e n t a g e o f t h e sa m p le composed o f sa n d s i z e d g r a i n s ( < 2 .0 0 mm t o 0 .0 6 2 mm) i s c a l c u l a t e d u s i n g t h e w e i g h t o f t h i s f r a c t i o n and t h e w e i g h t o f t h e e n t i r e p o r t i o n o f t h e sa m p le u s e d f o r t e x t u r a l a n a l y s i s . 388 Seven p e r c e n t o f th e s h e l f s a m p le s c o n t a i n e d some p a r t i c l e s l a r g e r t h a n 2 .0 0 mm. I n s u c h c a s e s an a d d i t i o n a l s c r e e n i n g a t t h i s l e v e l w as n e c e s s a r y t o s e p a r a t e t h e g r a v e l and s a n d f r a c t i o n s ; a n d p e r c e n t a g e d e t e r m i n a t i o n s w ere made o f b o t h s a n d a n d g r a v e l . (W im berley i n S te v e n s o n , 1 9 6 1 ; W im b erley , 1964; and i n AHF:USC, 1965) The s a n d f r a c t i o n (= " c o a r s e ” f r a c t i o n m inus g r a v e l ) and t h e " f i n e ” f r a c t i o n ( s i l t p l u s c l a y ) w ere a n a l y s e d s e p a r a t e l y u s i n g tw o s t a n d a r d p r o c e d u r e s , t h e s e t t l i n g tu b e m ethod (Em ery, 1938) f o r s a n d and t h e p i p e t t e m e th o d ( R i t t e n h o u s e , 1939, c i t e d i n s t a f f , AHF, 1958) f o r s i l t ( 0 . 0 6 2 - 0 . 0 0 4 mm) a n d c l a y ( 0 .0 0 4 mm). B o th m eth o d s a r e b a s e d on a k n o w led g e o f t h e s e t t l i n g v e l o c i t i e s o f p a r t i c u l a t e m a t t e r t h r o u g h w a t e r and c o n s i s t o f c o l l e c t i n g s e d im e n t f r a c t i o n s t h a t h av e s e t t l e d f o r a known p e r i o d o f tim e th r o u g h a s p e c i f i e d d i s t a n c e i n t e r v a l . C o a r s e r p a r t i c l e s s e t t l e f a s t e r (K rum bein and P e t t i j o h n , 1 9 3 8 ). W entw orth s i z e - c l a s s p e r c e n t i l e d a t a a r e com puted f ro m th e r e s u l t s o f b o t h a n a l y s e s ; t h e s e a r e com bined i n a s e m i l o g a r i t h m i c p l o t t o y i e l d a s i n g l e c u m u la tiv e p e r c e n t age f r e q u e n c y c u r v e . Q u a r t i l e m e a s u re m e n ts d e r i v e d fro m t h i s ty p e o f c u r v e p r o v i d e m ed ian d i a m e t e r (m id d le m o s t p a r t i c l e d i a m e t e r ) v a l u e s and t h e f i r s t ( 2 5 t h p e r c e n t i l e ) a n d t h i r d ( 7 5 t h p e r c e n t i l e ) q u a r t i l e v a l u e s f o r s o r t i n g c o e f f i c i e n t c a l c u l a t i o n s (K rum bein and P e t t i j o h n , 1 9 3 8 ). 389 The s o r t i n g c o e f f i c i e n t s r e p o r t e d a r e b y t h e m ethod o f T r a s k ( 1 9 3 2 ) : — D -------i --------- So = / . . F25 t h . / p7 5 th W im berley ( i n S te v e n s o n , 1961) a l s o r e p o r t s s o r t i n g a s p h i s t a n d a r d d e v i a t i o n (K rum bein and P e t t i j o h n , 1 9 3 8 ); i n h i s more r e c e n t work ( 1 9 6 4 ) , he r e p o r t s s o r t i n g by t h i s method e x c l u s i v e l y . The fo rm u la g iv e n f o r t h e T r a s k s o r t i n g c o e f f i c i e n t i n AHFrUSC (1 9 6 5 , page 127) i s i n c o r r e c t . Uchupi ( i n S te v e n s o n , 1961; and i n AHF:USC, 1965) m easu red o r g a n i c n i t r o g e n and c a r b o n a t e o f th e s e d im e n t sa m p le s c o l l e c t e d from t h e m a in la n d s h e l f . By th e K j e l d a h l method ( N i e d e r l and N i e d e r l , 1947) amine and amide n i t r o g e n a r e c o n v e r te d i n t o ammonium s u l p h a t e by d i g e s t i o n o f th e s a m p le " w ith s u l f u r i c a c i d . F o llo w in g d i g e s t i o n , th e s o l u t i o n i s made a l k a l i n e w i t h sodium h y d r o x id e ; t h e ammonium (NH^) l i b e r a t e d i n t h i s r e a c t i o n i s d i s t i l l e d i n t o a m eas u re d volume o f s ta n d a r d h y d r o c h l o r i c a c i d . The ammonium n e u t r a l i z e s a p o r t i o n o f th e a c i d . The e x c e s s h y d r o c h l o r i c a c id i s d e te r m in e d by t i t r a t i n g a g a i n s t a s t a n d a r d b a s e s o l u t i o n . The d i f f e r e n c e b etw een th e i n i t i a l q u a n t i t y o f h y d r o c h l o r i c a c i d and th e amount r e m a in in g i s t h e amount n e u t r a l i z e d by th e a m m o n iu m -n itro g e n . The p e r c e n t a g e o f n i t r o g e n (b y w e i g h t ) i n th e sample i s c a l c u l a t e d on th e b a s i s o f t h e amount o f n e u t r a l i z e d h y d r o c h l o r i c a c id ( S t a f f , AHF:USC, 1 9 5 8 ). 390 S e d im e n t c a r b o n a t e was d e te r m in e d by a g a s o m e tr i c method. (B ie n , 1952, c i t e d i n S t a f f , AHF, 1958) i n v o l v i n g ' th e o x i d a t i o n o f c a r b o n a t e s t o c a rb o n d i o x i d e by h o t s u l f u r i c a c i d . The am ount o f c a rb o n d i o x i d e p ro d u c e d i s m ea su re d i n a m anom eter. The p e r c e n t a g e o f c a lc iu m c a r b o n a te (b y w e ig h t) i s c a l c u l a t e d on t h e b a s i s o f t h e volume o f c a r b o n d i o x i d e t h a t r e s u l t s fro m t h i s r e a c t i o n a f t e r c o r r e c t i o n to s t a n d a r d c o n d i t i o n s o f t e m p e r a t u r e and p r e s s u r e ( S t a f f , AHF:USC, 1 9 5 8 ). H y d ro g ra p h ic S am pling M ethods and A n a ly s is C e r t a i n p h y s i c a l and c h e m ic a l v a r i a b l e s o f th e w a te r mass o v e r l y i n g b e n t h i c s a m p lin g a r e a s w ere i n v e s t i g a t e d . T e m p e ra tu re s i n t h e w a te r column t o a d e p t h o f 200 f e e t (= 61 m) w ere r e c o r d e d w i t h a b a th y th e r m o g r a p h o p e r a t ed f ro m a s m a l l u t i l i t y w in ch . As th e i n s t r u m e n t d e c e n d s (and a l s o as i t i s r a i s e d ) th e th e r m a l s t y l u s i n s c r i b e s a t e m p e r a t u r e - d e p t h t r a c e (= c u rv e ) on a c o a t e d g l a s s s l i d e . Each s l i d e i s l a b e l e d w i t h th e d a t e , b a th y th e r m o g r a p h s e r i a l num ber, and t h e tim e o r s t a t i o n number and l a t e r i s re a d w i t h a v ie w e r c a l i b r a t e d f o r th e p a r t i c u l a r b a t h y th e rm o g ra p h em ployed. The v ie w e r - b a th y th e r m o g r a p h c a l i b r a t i o n i s made by t h e m a n u f a c t u r e r o f t h e s e i n s t r u m e n t s . The s u r f a c e t e m p e r a t u r e i s r e a d f i r s t ; t h e d e p th s a t w h ich th e t e m p e r a t u r e v a l u e s a r e i n w hole d e g r e e s (°F ) a r e n o t e d ; 391 t e m p e r a t u r e s a r e c o n v e r t e d to °C and t h e n r e c o r d e d ( S t a f f , AHF:USC, 1 9 5 8 ). S u r f a c e t e m p e r a t u r e s w ere i n d i r e c t l y m eas u re d by p l a c i n g a l a b o r a t o r y th e rm o m e te r i n a b u c k e t o f w a te r drawn by hand a t t h e s i d e o f th e v e s s e l . S u r fa c e w a t e r s a m p le s f o r a n a l y s i s o f s a l i n i t y and i n o r g a n i c c h e m ic a l c o n s t i t u e n t s w ere a l s o c o l l e c t e d by th e b a i l i n g m ethod. W ater s a m p le s a t d e p th w ere c o l l e c t e d w i t h Nansen r e v e r s i n g b o t t l e s . The d e p t h s sam pled w ere 50 f e e t (= 1 5 .3 m ), 100 f e e t ( 3 0 . 5 m ), and a t 100 f o o t i n t e r v a l s b elow t h i s d e p t h . A s m a ll q u a n t i t y o f w a te r was draw n from e a c h b o t t l e f o r m easurem ent o f th e more t r a n s i t o r y c h e m ic a l c h a r a c t e r i s t i c s t h a t w ere a n a ly z e d a b o a rd th e r e s e a r c h v e s s e l . A somewhat l a r g e r f r a c t i o n o f th e sam ple was t r a n s - f e r e d t o a p i n t (= 2 .1 1) p l a s t i c b o t t l e f o r s a l i n i t y d e t e r m i n a t i o n made i n t h e l a b o r a t o r y on s h o r e . B o t t l e s w ere i d e n t i f i e d w ith t h e s t a t i o n num ber. D i s s o l v e d oxygen was m e a su re d on b o a rd t h e s h i p b y th e Pom eroy-K irchm an (1 9 4 5 , c i t e d i n S t a f f , AHP, 1958) m o d i f i c a t i o n o f t h e W in k le r m ethod ( T ib b y , i n S te v e n s o n , 1961; AHFrUSC, 1 9 6 5 ). T h is method i n v o l v e s th e o x i d a t i o n o f m anganous h y d r o x id e , by d i s s o l v e d o x y g en , to y i e l d m anganic h y d r o x id e . W ith th e a d d i t i o n o f s u l f u r i c a c i d , th e l a t t e r compound o x i d i z e s i o d i d e to i o d i n e . The y i e l d o f f r e e i o d i n e i s d e te r m in e d b y t i t r a t i o n a g a i n s t a sodium t h i o s u l f a t e s t a n d a r d s o l u t i o n and i s e q u i v a l e n t t o a q u an t i t y o f d i s s o l v e d oxygen p r e s e n t i n th e o r i g i n a l sam ple 392 ( S t a f f , AHFrUSC, 1 9 5 8 ). V a lu e s w ere r e p o r t e d i n m l / l i t e r . The m ethod f o r d e t e r m i n a t i o n o f p h o s p h a te was t h a t of R o b in so n and Thompson ( 1 9 4 8 ) . I n t h i s t e c h n i q u e when a s u l f u r i c a c id s o l u t i o n o f ammonium m o ly b d a te i s added to th e sample c o n t a i n i n g a s o l u b l e p h o s p h a te , a com plex p h o sp h o - m oly b d ic a c i d fo rm s . The com plex a c i d i s r e d u c e d t o a b l u e - c o l o r e d s u b s t r a t e upon t r e a t m e n t w ith a r e d u c i n g a g e n t such as s ta n n o u s c h l o r i d e . The c o n c e n t r a t i o n o f th e p h o s p h a te i s p r o p o r t i o n a l to th e c o l o r d e v e lo p e d ( S t a f f , AHF:USC, 1958) . P r i o r t o 1957, v i s u a l c o m p a riso n s w ere made w i t h s t a n d a r d c o l o r i m e t r i c s o l u t i o n s . S u b s e q u e n tl y , th e c o m p a riso n s w ere made u s i n g a 10-cm q u a r t z c e l l i n a Beckman Model DU S p e c tr o p h o to m e te r on b o a rd s h i p . P h o sp h a te d e t e r m i n a t i o n s w ere made a t a wave l e n g t h o f 690 m i l l i m i c r o n s u s in g th e r e d p h o to tu b e . . . (AHF:USC, 1965, p. 7 9 ) I n o r g a n i c s i l i c a t e d e t e r m i n a t i o n s w ere made by th e m ethod o f R o b in so n and Thompson ( 1 9 4 8 ) . T h is i s a l s o a c o l o r i m e t r i c m ethod; i n t h e p r o p e r h y d r o g e n - i o n c o n c e n t r a t i o n s i l i c a t e i s c o n v e r te d by m o ly b d a te i n t o a y e llo w - c o lo r e d compound. The s t r e n g t h o f th e c o l o r i s p r o p o r t i o n a l to t h e q u a n t i t y o f s i l i c a t e p r e s e n t i n t h e sa m p le . I n i t i a l a n a l y s e s were made by v i s u a l c o m p a r is o n s ; l a t e r s i l i c a te d e t e r m i n a t i o n s w ere made w i t h th e s p e c t r o p h o t o m e t e r a t a wave l e n g t h o f 400 m i l l i m i c r o n s u s i n g a b lu e p h o to tu b e (AHFrUSC, 1 9 6 5 ). A tte m p ts w ere made to a n a ly z e s e a w a te r q u a n t i t a t i v e l y f o r n i t r a t e . T ib b y ( i n S te v e n s o n , 1961; and i n 393 AHF: USC, 1965) s t a t e s t h a t : P r i o r t o th e summer of 1958, n i t r a t e d e t e r m i n a t i o n s were made by t h e c o l o r i m e t r i c m ethod o f W at- t e n b e r g (1 9 3 7 ) b u t t h e y were n o t s a t i s f a c t o r y from t h e s t a n d p o i n t o f e i t h e r a c c u r a c y or c o n v e n ie n c e . A f t e r t h a t d a t e , a n o t h e r m ethod w h ich seemed t o e l i m i n a t e t h e c o m p lic a te d r e a g e n t s and o t h e r d i s t u r b i n g f a c t o r s was u s e d ( M u llin and R i l e y , 1 9 5 5 ), b u t i t now a p p e a r s t h a t t h e r e i s some q u e s t i o n as t o t h e r e l i a b i l i t y o f t h i s m ethod a l s o . A s a t i s f a c t o r y a n a l y t i c a l t e c h n i q u e f o r n i t r a t e h a s y e t to be d e v i s e d . For t h i s r e a s o n , th e r e s u l t s o f t h e n i t r a t e d e t e r m i n a t i o n w i l l b e d i s c u s s e d o n ly i n gen e r a l t e r m s . ( p . 102) N o rm a lly i n o c e a n o g ra p h y , v a l u e s f o r p h o s p h a te , s i l i c a t e , and n i t r a t e a r e r e p o r t e d i n m ic ro -g ra m atom s p e r l i t e r , b u t , a t t h e d i r e c t i o n o f th e R e s e a r c h C o n s u l t i n g B o ard , m a rin e s c i e n t i s t s o f th e F o u n d a tio n were r e q u i r e d t o r e p o r t v a l u e s f o r t h e s e p a r a m e t e r s i n m i l l i g r a m s p e r l i t e r . S a l i n i t y i s a d e f i n e d q u a n t i t y and i n p r a c t i c e i s n o t d e te r m in e d d i r e c t l y , b u t i s c a l c u l a t e d on th e b a s i s o f c h l o r i n i t y : S a l i n i t y = 0 .0 3 + 1 .8 0 5 x C h l o r i n i t y . C h lo r - i n i t y i s a l s o a d e f i n e d q u a n t i t y , a s i t i s n o t a c t u a l l y e q u a l t o th e t o t a l amount o f c h o r i n e i n a sample o f s e a w a t e r . I n th e t i t r a t i o n w i t h s i l v e r n i t r a t e , t h a t form s th e b a s i s o f t h e s t a n d a r d method o f d e t e r m i n a t i o n , b ro m id e s and i o d i d e s a r e p r e c i p i t a t e d w i t h th e c h l o r i d e s , and i n t h e c o m p u ta tio n a r e t r e a t e d a s s u c h . P o ta s s iu m c h ro m ate i s u se d a s th e i n d i c a t o r . A l l a n a l y t i c a l w o r k 'i s r e l a t e d d i r e c t l y ( o r i n d i r e c t l y i n th e c a s e o f s e c o n d a ry s t a n d a r d s ) t o p r im a r y s t a n d a r d s , s o - c a l l e d "Normal W a te r ," p r e p a r e d by th e H y d r o g ra p h ic L a b o r a t o r i e s i n C openhagen, Denmark 394 ( S v e r d r u p , J o h n so n and F le m in g , 1 9 4 2 ). S a l i n i t y and c h l o r i n i t y v a l u e s a r e r e p o r t e d a s p a r t s p e r t h o u s a n d s . M easurem ents w ere made o f two p h o t o m e t r i c q u a l i t i e s o f th e s h e l f w a t e r . A S e c c h i d i s k was em ployed t o m easu re v i s u a l t r a n s p a r e n c y ; t h i s i s d e f i n e d a s th e g r e a t e s t d e p th to w hich th e d i s c can be s e e n b e f o r e i t d i s a p p e a r s a g a i n s t t h e b a c k g ro u n d o f s c a t t e r e d l i g h t . The p h y s i c a l t r a n s m i s s i o n o f l i g h t th ro u g h th e w a te r column i s d e te r m in e d by th e u se o f p h o t o e l e c t r i c c e l l s . The c u r r e n t p r o d u c t i o n o f a d e c k c e l l i s com pared w i t h t h a t o f a c e l l a t d e p t h . The r e s u l t i s e x p r e s s e d a s a n u m e r ic a l c o e f f i c i e n t t h a t i s a f u n c t i o n o f th e amount o f l i g h t a b s o rb e d p e r u n i t l e n g t h (T ib b y , i n S te v e n s o n , 1961; and i n AHF:USC, 1 9 6 5 ). The r e s u l t s o f th e a n a l y s e s c o n c e r n in g t h e p h y s i c a l t r a n s m i s s i o n o f l i g h t i n t h e w a t e r s o v e r th e m a in la n d s h e l f a re n o t r e p o r t e d i n th e p r e s e n t p a p e r . APPENDIX C THE SOUTHERN CALIFORNIAN MARINE REGION T h is a p p e n d ix i n c l u d e s a c o m p re h e n siv e d e s c r i p t i o n of t h e s o u th e r n C a l i f o r n i a n m a rin e r e g i o n . P a r t i c u l a r em p h a s i s i s p l a c e d on t h e c h a r a c t e r i s t i c s o f t h e p h y s i c a l e n v iro n m e n t o f t h e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f . The C o n t i n e n t a l B o rd e rla n d A c c o rd in g to Emery ( I 9 6 0 , p. 4 ) , . . . th e s e a f l o o r betw een t h e m a in la n d s h o r e l i n e and th e c o n t i n e n t a l s lo p e o f f s o u th e r n C a l i f o r n i a i s much more com plex th a n t y p i c a l c o n t i n e n t a l s h e l v e s o f most o t h e r a r e a s o f th e w o r ld . He s t r e s s e s th e f a c t t h a t i t s f e a t u r e s a r e u n iq u e f o r th e se a f l o o r , b e lo n g in g n e i t h e r t o t h e c o n t i n e n t a l s h e l f , t o th e c o n t i n e n t a l s lo p e n o r th e a b y s s a l s e a f l o o r . I n s t e a d , th e y a r e s i m i l a r to f e a t u r e s o f th e n e a r b y lan d a r e a , w hich he a l s o c o n s i d e r s u n iq u e i n t h e w o rld . Menard (1964) d o u b ts t h a t th e a r e a i s u n i q u e . He c o n s i d e r s i t s i m i l a r to o th e r d e e p s h e l v e s e x c e p t f o r i t s r e l a t i v e l y s m a ll s i z e and th e f a c t t h a t i t i s b ro k e n i n t o s m a ll f a u l t b l o c k s . Such s m a l l - s c a l e b lo c k f a u l t i n g may be common e ls e w h e re and know ledge o f i t s e x i s t e n c e o f f 395 396 s o u t h e r n C a l i f o r n i a may r e f l e c t o n ly t h e p r o x i m i t y of n e a r by o c e a n o g r a p h ic i n s t i t u t i o n s . U nique o r n o t , t h e p o r t i o n o f t h e s e a f l o o r o f f s o u t h e r n C a l i f o r n i a and n o r t h e r n B a ja C a l i f o r n i a (M exico) i s s u f f i c i e n t l y d i f f e r e n t and s u f f i c i e n t l y com plex t h a t i t h a s b een d e s i g n a t e d by a s p e c i a l te r m , " t h e c o n t i n e n t a l b o r d e r l a n d " (S h e p a rd and Emery, 1 9 4 1 ). I t s n o r t h e r n l i m i t , P o i n t A r g u e l l o , C a l i f o r n i a , and i t s s o u th e r n l i m i t , C ed ro s I s l a n d , B a ja C a l i f o r n i a , r e p r e s e n t lan d w ard p r o j e c t i o n s o f th e M u rra y E sc a rp m e n t and t h e C e d ro s E s c a rp m e n t r e s p e c t i v e ly (U ch u p i and Emery, 1 9 6 3 ) . The e a s t e r n and w e s t e r n l i m i t s a r e th e s h o r e l i n e and th e c o n t i n e n t a l s l o p e , th e P a t t o n E s c a rp m e n t. The a b y s s a l s e a f l o o r seaw ard o f th e b o r d e r lan d i s th e e a s t e r n p o r t i o n o f th e B a ja C a l i f o r n i a Seam ount P r o v in c e (M enard, 1 9 6 4 ). A p p a r e n t l y th e p o r t i o n o f th e su b m a rin e c o n t i n e n t a l m a rg in b etw een C ed ro s I s l a n d and P o in t C o n c e p tio n has u n d e rg o n e a b ro a d downwarp. The d e f o r m a t i o n o c c u r r e d i n p r e - P l e i s t o c e n e t i m e s , b u t i t i s n o t known i f i t p re c e d e d or f o llo w e d t h e s m a l l - s c a l e b lo c k f a u l t i n g . The to p o g ra p h y p r o b a b ly d e v e lo p e d i n p r e - P l i o c e n e tim e s i n b o th t h e s e a f l o o r and t h e w e s t e r n p a r t o f th e B a sin -R a n g e p r o v in c e on l a n d . These two a r e a s a re now s e p a r a t e d by t h e T r a n s v e r s e R anges (Em ery, 1 9 6 0 ). Thus th e c o n t i n e n t a l b o r d e r l a n d r e p r e s e n t s a w e l l - d e f i n e d m a rin e r e g i o n , c l o s e l y r e l a t e d t o t h e a d j o i n i n g la n d m ass and d e l i m i t e d by c o n t i n e n t a l e x t e n s i o n s o f p r o m in e n t su b m a rin e 397 t o p o g r a p h ic f e a t u r e s . Emery (1 9 6 0 , p. 107) h a s g iv e n an e x c e l l e n t g e n e r a l d e s c r i p t i o n o f t h e s o u t h e r n C a l i f o r n i a n p o r t i o n o f t h i s b o r d e r l a n d (A p p en d ix F ig u r e C - l ) : I n g e n e r a l , th e r e g i o n c o n s i s t s o f many b l o c k s o f r o u g h ly e q u a l s i z e t h a t b e a r a c l o s e re se m b la n c e to t h e f a u l t b l o c k s o f th e B a s in Range p r o v in c e i n N evada and e a s t e r n C a l i f o r n i a . . . . For c o n v e n ie n c e th e b l o c k s w i l l be r e f e r r e d to as h o r s t s and g r a b e n s th o u g h l a t e r work may show t h a t some o f them a r e due t o f o l d i n g r a t h e r t h a n to s im p le b l o c k f a u l t i n g . Many o f t h e h o r s t s r i s e t o r e l a t i v e l y s h a llo w d e p t h s b e n e a t h th e o cean s u r f a c e as b an k s o r even r i s e above s e a l e v e l a s i s l a n d s . F l a t s h e l v e s , a q u a r t e r o f a m ile t o 15 m i l e s w id e , f r i n g e th e m a r g in s o f th e i s l a n d s and o f th e m a in la n d . . . . T h e ir seaw ard e d g e s g e n e r a l l y a r e 150 f e e t to 450 f e e t d e e p . The t o p s o f s h a ll o w e r b a n k s a l s o a r e f l a t , or a re m arked by s m a ll e r o s i o n a l re m n a n ts t h a t r i s e above th e g e n e r a l l e v e l . S i m i l a r s h e lv e s now above s e a l e v e l on i s l a n d s and m a in la n d a r e r e c o g n i z e d as e l e v a t e d w a v e - c u t t e r r a c e s . T r a n s v e r s e t o th e s h e l v e s a r e su b m a rin e v a l l e y s and c an y o n s t h a t p a r t i a l l y or e n t i r e l y c r o s s th e s h e l v e s and c o n t i n u e down th e a d j o i n i n g s l o p e s . T hese f e a t u r e s a re p r e s e n t a lo n g th e m a in la n d , o f f s e v e r a l of t h e i s l a n d s , and even a t th e s i d e o f a t l e a s t one b a n k . . . . B etw een th e h o r s t s a r e g r a b e n s t h a t form 13 or 14 d i s t i n c t c lo s e d b a s i n s and one t r o u g h . The b o t toms o f s e v e r a l o f th e b a s i n s a r e a s much a s 6,000 f e e t belo w th e to p s o f th e a d j a c e n t h o r s t s . T hese v e r t i c a l d i f f e r e n c e s may have b e e n ev en g r e a t e r b e f o r e e r o s i o n lo w e re d th e h o r s t s and s e d im e n ts p a r t i a l l y f i l l e d th e b a s i n s . . . . The T r a n s v e r s e Range p r o v i n c e , a sy ste m o f f o l d s and t h r u s t f a u l t s w ith an e a s t - w e s t t r e n d , o c c u p ie s th e n o r t h e r n p o r t i o n o f th e s o u t h e r n C a l i f o r n i a n b o r d e r l a n d and th e a d j a c e n t la n d a r e a s ( B a r b a t , 1958; C a l i f o r n i a , Shaded R e l i e f , 1949[1961] USGS; and S a n ta M aria S h e e t , 1959, D iv. M in es, S t a t e o f C a l i f o r n i a ) . I t s t o p o g r a p h ic f e a t u r e s APPENDIX FIGURE C-l A Map o f th e S o u th e rn C a l i f o r n i a n C o n t i n e n t a l B o r d e r l a n d Showing t h e M a in la n d S h e l f , t h e O f f s h o r e B a s i n s C c o n to u r i n t e r v a l s i n d i c a t e b a s i n s i l l d e p t h s ; i n d i v i d u a l s o u n d in g s i n e a c h b a s i n i n d i c a t e th e d e e p e s t p o i n t ) , th e O f f s h o r e I s l a n d s , and th e P a t t o n E s c a r p m e n t. ( A f t e r S h e p a rd and Em ery, 1 9 4 1 ). 398 Figure C-l 'courts' NAUTICAL W i l l ! (AFTER SHERARO AND EMERY, I M I, CHART I) CONTINENTAL BORDERLAND OF SOUTHERN CALIFORNIA 400 a b r u p t l y i n t e r r u p t th e d o m in a n t n o r t h w e s t - s o u t h e a s t t r e n d i n g f e a t u r e s t y p i c a l o f C a l i f o r n i a n to p o g r a p h y . The T r a n s v e r s e sy ste m h as b e e n c o n s i d e r e d a m a jo r g e o l o g i c a l a n o m a ly , b u t i t may r e p r e s e n t a la n d w a rd e x t e n s i o n o f th e M u rra y E s c a r p ment ( B a r b a t , 195 8 ; M en ard , 1964; U chupi and E m ery, 1 9 6 3 ). The m a rin e e l e m e n t s o f t h e T r a n s v e r s e Range p r o v in c e w i t h i n th e c o n t i n e n t a l b o r d e r l a n d a r e ( 1 ) th e i s l a n d s o f th e A n a c a p a --S a n M ig u e l c h a i n and t h e i r s h e l v e s and s l o p e s , ( 2 ) th e S a n t a B a r b a r a Deep B a s in and i t s s l o p e s , and ( 3 ) t h e C o n c e p t i o n - - V e n t u r a p o r t i o n o f t h e m a in la n d s h e l f . A l l o f t h e s e f e a t u r e s have a g e n e r a l e a s t - w e s t t r e n d ( C h a r t 1, S h e p a rd and E m ery, 1941, a s r e p r o d u c e d i n Em ery, 1 9 6 0 ). South o f th e A n a c a p a - - S a n M ig u e l I s l a n d c h a i n th e t o p o g r a p h ic co m p o n en ts o f th e b o r d e r l a n d s y s te m h av e a n o r t h w e s t - s o u t h e a s t o r i e n t a t i o n p a r a l l e l i n g t h e P e n i n s u l a Range p r o v in c e on s h o r e . H ere th e s i l l s , b a n k s and i s l a n d s s e p a r a t e th e e n c l o s e d b a s i n s and open t r o u g h s i n t o r o u g h l y a r r a n g e d p a r a l l e l g r o u p s : ( 1 ) S a n t a M onica B a s i n , San P e d ro B a s in and t h e San D iego T ro u g h n e a r s h o r e ; ( 2 ) S a n ta C a t a l i n a B a s in and San C lem en te B a s in se a w a rd o f S a n t a C a t a l i n a I s l a n d and T h i r t y m i l e and F o r t y m i l e B a n k s ; ( 3 ) S a n ta Cruz B a s i n , San N i c o l a s B a s i n , E a s t C o r t e s B a s i n , and No Name B a s in se a w a rd o f S a n ta B a r b a r a I s l a n d , San C lem en te I s l a n d and S i x t y m i l e B ank; ( 4 ) T a n n e r B a s i n , W est C o r t e s B a s i n , Long B a s i n and V e l e r o B a s in s e a w a rd o f t h e S a n t a R o s a - - C o r t e s R id g e and C o r t e s Bank (E m ery , 1 9 6 0 ). 401 The i s l a n d s a r e c o n c e n t r a t e d i n th e n o r t h e r n h a l f o f th e b o r d e r l a n d and m ost o f th e d e e p b a s i n s a r e l o c a t e d i n th e s o u t h e r n h a l f . G e n e r a l l y , b a s i n d e p th i n c r e a s e s i n a seaw ard d i r e c t i o n b e tw e e n g ro u p s and i n a s o u t h e a s t e r n d i r e c t i o n w i t h i n any p a r t i c u l a r g ro u p (Em ery, 1960; Hartm an and B a r n a r d , 1 9 5 8 ). The C o a s t l i n e The s o u t h e r n C a l i f o r n i a n c o a s t l i n e i s i n t h e form o f a s h a llo w co n cav e i n d e n t a t i o n . Over i t s 486 k i l o m e t e r l e n g t h (Em ery, 1960) i t s t r e n d c h a n g e s from e a s t - w e s t (A re a I ) t o n o r t h - s o u t h (A rea V I I I ) . The a r c u a t e form o f th e c o a s t l i n e c o r r e s p o n d s to t h e change i n t r e n d o f th e two d o m in an t s t r u c t u r a l p r o v i n c e s o f t h e a r e a , th e T r a n s v e r s e Range p r o v in c e and t h e P e n i n s u l a r Range p r o v in c e (W im b e rley , in S t e v e n s o n , 1961; W im berley, 1 9 6 4 ). From P o i n t C oncep t i o n t o V e n tu r a , th e s t e e p , e a s t - w e s t t r e n d i n g S a n ta Ynez m o u n ta in s b o r d e r th e s e a . The c o a s t l i n e p a r a l l e l s t h e i r t r e n d . A b ro a d a l l u v i a l p l a i n , th e O xnard P l a i n , a c c o u n ts f o r t h e sm o o th , g e n t l y c u r v i n g , convex s h o r e l i n e b e tw e e n V e n tu r a and P o i n t Mugu. E a s t o f P o i n t Mugu, th e s h o r e l i n e a g a i n h a s an e a s t - w e s t t r e n d and a g a i n i s b ack ed by a moun t a i n ra n g e w i t h s i m i l a r o r i e n t a t i o n , th e S a n ta M onica moun t a i n s . The S a n ta Ynez and th e S a n ta M onica m o u n ta in s b e lo n g t o th e T r a n s v e r s e Range p r o v i n c e . The b ro a d Los A n g e le s P l a i n l i e s a t th e b o u n d a ry o f th e two m o u n ta in 402 ra n g e p r o v i n c e s , s e p a r a t i n g t h e S a n ta M onica m o u n ta in s from th e S a n ta Ana m o u n ta in s o f th e P e n i n s u l a Range p r o v in c e . I t s sm ooth c o a s t a l p r o f i l e i s i n t e r r u p t e d o n ly by th e P a l o s V erd es H i l l s . South o f Los A n g e le s t h e c o a s t l i n e p a r a l l e l s th e s o u th e a s t w a r d t r e n d o f t h e S a n ta Ana m o u n ta in s f o r a d i s t a n c e o f n e a r l y 100 m i l e s (= 161 km ). S o u th o f P o i n t Loma a t San D ieg o t h e r e i s a n o t h e r r e l a t i v e l y l a r g e d e p o s i - t i o n a l a r e a ( S te v e n s o n , Uchupi and G o r s l i n e , 1959; S t e v e n son [ a ] , i n S te v e n s o n , 1961; W im b erley , i n S te v e n s o n , 1961; W im berley, 1 9 6 4 ). T h u s, th e g e n e r a l c o n f i g u r a t i o n o f th e s o u t h e r n C a l i f o r n i a n c o a s t l i n e i s d e te r m in e d by th e m a jo r s t r u c t u r a l com ponents ( S t e v e n s o n , U chupi and G o r s l i n e , 1 9 5 9 ). Some s m a l l e r i r r e g u l a r i t i e s o f th e s h o r e l i n e a r e a l s o c a u se d by s t r u c t u r a l f a c t o r s ; c o n s p ic u o u s p o i n t s o c c u r a t s e v e r a l l o c a t i o n s w here a n t i c l i n e s and f a u l t s i n t e r s e c t th e s h o r e . B ut i n most c a s e s , p o i n t s and h e a d la n d s r e s u l t from th e e x p o s u re o f r o c k s o f v a r y in g d e g r e e s o f r e s i s t a n c e to th e e r o s i o n a l f o r c e s o f t h e s e a ( S te v e n s o n , Uchupi and G o r s l i n e , 1 9 5 9 ). Emery (1 9 6 0 ) made an a n a ly s is o f th e s h o r e l i n e f a c in g t h e open o c e a n . "B ased on h i s d a t a , 16.5% i s r o c k y , 26.4% i s sandy and b a c k e d by lo w la n d s , and 57.1% i s san d y and b ack ed by c l i f f s ” (G. J o n e s , 1964; p. 4 7 ) . A c c o rd in g to Emery, th e e r o s i o n a l c o a s t s o f s o u th e r n C a l i f o r n i a c o n s i s t c h i e f l y o f s e a c l i f f s . Sand b e a c h e s or t a l u s s e p a r a t e 403 most c l i f f s from th e s e a e x c e p t d u r in g s e a s o n a l p e r i o d s o f e r o s i o n . Some c l i f f s a r e c o n t i n u o u s l y e x p o s e d t o th e f o r c e s o f th e s e a . D e p o s i t i o n a l c o a s t s i n s o u t h e r n C a l i f o r n i a co n s i s t c h i e f l y o f sandy b e a c h e s . About 30 p e r c e n t o f t h e sand b e a c h e s a r e b acked by lo w la n d s , c o n s i s t i n g m o s tly o f m a rsh e s and mud f l a t s , and t h e s e a r e a s a r e t h e o n ly t r u l y d e p o s i t i o n a l r e g i o n s o f t h e c o a s t (Em ery, 1960) . The V e n tu r a and S a n ta C l a r a R i v e r s , t h e l a r g e r i v e r s a s s o c i a t e d w ith one o f t h e s e d e p o s i t i o n a l a r e a s , d r a i n th e S a n ta Ynez m o u n ta in s . The fo rm e r d i s c h a r g e s i n t o th e s e a n o r t h o f V e n tu r a , and t h e l a t t e r c r o s s e s th e Oxnard P l a i n and r e a c h e s th e s e a s o u t h o f . V e n t u r a . The S a n ta C l a r a R iv e r d i s c h a r g e s th e l a r g e r volume a n n u a l l y . The Los A n g e le s , San G a b r i e l and S a n ta Ana R i v e r s d r a i n th e s o u t h s i d e o f t h e San G a b r i e l and San B e r n a r d in o M o u n ta in s , c r o s s th e Los A n g e le s B a s in and em pty i n t o San Pedro Bay n e a r Long B each, S e a l Beach and New port Beach r e s p e c t i v e l y . The S a n ta M a r g a r i t a and San L u is Rey R i v e r s d r a i n t h e w e s t e r n s l o p e s o f t h e S a n ta Ana M o u n ta in s and d i s c h a r g e n o r t h o f O c e a n s id e . S m all d e p o s i t i o n a l a r e a s a r e a s s o c i a t e d w ith t h e m ouths o f t h e s e two s tr e a m s . The San D iego R iv e r d r a i n s a p a r t o f th e c o a s t ra n g e and d i s c h a r g e s a t M is s io n Bay. The T i j u a n a R iv e r d r a i n s a l a r g e p o r t i o n o f th e c o a s t a l m o u n ta in s b o th above and b e lo w th e I n t e r n a t i o n a l B oundary and r e a c h e s t h e s e a s o u th o f San D ieg o Bay. Many s m a l l e r s tr e a m s e x i t t o th e s e a a lo n g th e e n t i r e c o a s t , b u t t h e y a re a l l d ry e x c e p t 404 d u r in g th e r a i n y s e a s o n (W im b e rley , i n S te v e n s o n , 1961; W im berley, 1964; and i n AHF:USC, 1 9 6 5 ). The M ain lan d S h e l f The m a in la n d s h e l f o f s o u t h e r n C a l i f o r n i a i s t h e n a rro w s t r i p o f ocean b o tto m l y i n g im m e d ia te ly a d j a c e n t t o th e la n d b e tw e e n P o i n t C o n c e p tio n on th e n o r t h and th e Mex i c a n b o r d e r on t h e s o u th ( " P r i n c i p a l S tu d y A r e a , " A p p en d ix F ig u re C -2; AHF:USC, 1965, F ig u re l . A ) . The d e p th o f t h e o u te r edge o f t h e s h e l f v a r i e s b e tw e e n 73 an d 128 m e t e r s , b u t 9 1 .4 m e t e r s ( t h e 50 fa th o m c o n t o u r o f C o a s t and G e o d e t i c C h a r t s 5101, 5202) may be em ployed as t h e p r a c t i c a l s e a ward l i m i t (G. J o n e s , 1 9 6 4 ) . The w id th o f t h e m ain lan d s h e l f v a r i e s b e tw e e n 22.0 k i l o m e t e r s and 0 .8 k i l o m e t e r s . The w id e r p o r t i o n s a re t h e S a n ta B a r b a r a s h e l f (maximum w i d t h , 1 7 .6 k i l o m e t e r s ) , t h e S a n ta M onica Bay s h e l f ( 1 8 .0 k i l o m e t e r s ) , t h e San P e d ro Bay s h e l f ( 2 2 .0 k i l o m e t e r s ) and th e San D iego s h e l f ( 1 6 .3 k i l o m e t e r s ) . The s h e l f i s n a r ro w e s t w here t h e h e a d s o f su b m arin e can y o n s ap p ro a c h th e s h o r e , a s a t t h e h e a d s o f Hueneme, Mugu, Dume, Redondo and La J o l l a su b m a rin e c an y o n s (G. J o n e s , 1 9 6 4 ). The s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f c o m p ris e s 3639 s q u a re k i l o m e t e r s (1 0 6 1 s q u a re n a u t i c a l m i l e s ) o f s e a b o tto m b e tw e e n 0 and 1 8 2 .8 m e te r s (100 f a t h o m s ) . E i g h t y - s i x p e r c e n t (3 1 4 2 s q u a re k i l o m e t e r s or 916 s q u a re n a u t i c a l m ile s ) o f t h i s a r e a i s s h a ll o w e r th a n 9 1 .4 m e te r s (50 APPENDIX FIGURE C-2 A G e n e r a l Map o f t h e S o u th e r n C a l i f o r n i a n C o a s t a l A rea Showing th e M ain lan d S h e l f , t h e P r i n c i p a l S tu d y A re a ( F ig u r e l.A , AHF:USC, 1 9 6 5 ). 405 SAN O A O N IILV v n > 00' - ! SANTA CR UZ BLAND SANTA R O | t llL A N O ISLAND SANTA SANT A CATAUNA ISLAND — v S O U T H E R N CA UKJ RW A C O A S T A L AREA truer F ig u re C-2 o 407 f a th o m s ) . A c c o rd in g t o Emery ( I 9 6 0 ) th e m a in la n d s h e l f makes up o n ly 6.2 p e r c e n t o f th e a r e a o f th e c o n t i n e n t a l b o r d e r l a n d . G. J o n e s (1 9 6 4 , p . 47) com pared t h e d i s t r i b u t i o n o f th e b o tto m a r e a by d e p t h c l a s s e s w i t h i n e a c h s h e l f a r e a w i t h t h a t f o r th e m a in la n d s h e l f a s a u n i t . T h is a n a l y s i s was b a s e d on d a t a y i e l d e d by th e p l a n i m e t r i c m ethod of B a rn a rd and J o n e s ( 1 9 6 0 ) . These d a t a a r e i n c l u d e d i n T a b le 1 o f th e m ain body o f t h i s p a p e r . The d i s t r i b u t i o n o f b o tto m a r e a by d e p th c l a s s e s i s e s s e n t i a l l y th e same a s t h a t f o r th e e n t i r e m a in la n d s h e l f i n a l l r e g i o n s e x c e p t A rea I , th e d e e p e s t s h e l f s u b d i v i s i o n , A re a I l a , th e n e x t d e e p e s t , A re a l i b , t h e s h a l l o w e s t s u b d i v i s i o n , and A rea V I, th e n e x t s h a l l o w e s t . More th a n 50% o f t h e P o i n t C oncep t i o n s h e l f l i e s d e e p e r th a n 55 m, w h e re a s o n ly 30% o f th e a r e a o f t h e t o t a l m a in la n d s h e l f i s below t h i s d e p t h . I n t h e c ase o f th e S a n ta B a r b a r a s h e l f , i f th e 37 m c o n to u r i s s e l e c t e d , th e f o l l o w i n g com p a r i s o n s may be m ade: i n A re a I l a 66.5% o f th e s h e l f l i e s b elo w t h i s d e p t h , w h i l e i n A re a l i b o n ly 22.4% i s d e e p e r t h a n 37 m. The a r e a o f th e m a in la n d s h e l f below 37 m i s 49%. The d i s t r i b u t i o n o f b o tto m a r e a by d e p th c l a s s e s f o r t h e San P e d ro s h e l f i s s i m i l a r t o t h a t i n A rea l i b ; h e re 59% o f th e b o tto m l i e s i n w a te r d e p t h s of l e s s th a n 37 m. The f l o o r o f t h e s h e l f i s g e n e r a l l y a n e a r l y smooth s l o p e , b u t i t i s n o t w i t h o u t d i s t i n c t i v e f e a t u r e s . Ten ma j o r su b m a rin e can y o n s t r a n s e c t th e s h e l f ; some e x te n d l a n d w ard to w i t h i n a h a l f a m ile (= 0 . 8 km) o f s h o r e . S h a llo w d e p r e s s i o n s , m inor t e r r a c e s and ru g g ed m i c r o - r e l i e f a l s o o c c u r on t h e s h e l f (W im berley, i n S te v e n s o n , 1961; Wimber l e y , 1964; Emery, 1 9 6 0 ). 408 A G e n e r a l C o n s i d e r a t i o n o f S e d im e n ts o f t h e M ain la n d S h e l f P r i o r t o t h e A l l a n Hancock F o u n d a tio n s u r v e y , com p r e h e n s i v e i n v e s t i g a t i o n s w ere made o f th e b o tto m s e d im e n ts on th e s h e l f b e tw e e n S a n ta B a r b a r a and G a v i o t a on th e n o r t h e r n p o r t i o n o f th e s h e l f , and on th e t h r e e b r o a d s e g m e n ts o f t h e s o u t h e r n s h e l f , S a n ta M onica B ay, San P e d ro Bay and o f f San D ie g o (E m ery, 1 9 6 0 ). T h e re have a l s o b e e n s e v e r a l s t u d i e s o f s m a l l e r a r e a s n e a r s h o r e (W im b e rle y , i n S t e v e n s o n , 1961; W im b erle y , 1964; and i n AHFtUSC, 1 9 6 5 ) . E x t e n s i v e and d e t a i l e d i n v e s t i g a t i o n s w ere made o f t h e t e x t u r a l p r o p e r t i e s and some o f th e c h e m ic a l p r o p e r t i e s o f th e m a in la n d s h e l f s e d im e n ts by t h e g e o l o g i s t s o f th e F o u n d a tio n s u rv e y g r o u p . R e s u l t s o f t h e s e s t u d i e s a r e r e p o r t e d b y S t e v e n s o n , U chupi and G o r s l i n e ( 1 9 5 9 ) , W im berley ( i n S t e v e n s o n , 1961) and W im berley (1 9 6 4 ) f o r p h y s i c a l p r o p e r t i e s ; th e c h e m ic a l p r o p e r t i e s o f th e s h e l f s e d im e n ts a r e r e p o r t e d by S te v e n s o n , U chupi and G o r s l i n e (1 9 5 9 ) and U chupi ( i n S te v e n s o n , 1 9 6 1 ) . Much o f t h i s i n f o r m a t i o n i s r e p e a t e d i n AHF:USC ( 1 9 6 5 ) . Emery (1 9 6 0 ) i n c l u d e s an e x c e l l e n t , c o n c i s e d i s c u s s i o n o f th e g e o lo g y o f th e m a in la n d s h e l f . The f o l l o w i n g d e s c r i p t i o n su m m a riz e s i n f o r m a t i o n from t h e s e s o u r c e s . I t i s i n c l u d e d i n t h i s r e p o r t i n o r d e r t o p r o v i d e r e a d i l y a c c e s s i b l e b a c k g ro u n d f o r th e b i o l o g i c a l d a t a . The N a tu r e and O r i g i n o f th e S h e l f S e d im e n ts G e o l o g i s t s have u s e d two v e r y d i f f e r e n t a p p r o a c h e s to th e m a t t e r o f d e s c r i b i n g s e d i m e n t s . One i s a q u a n t i t a t i v e o r s t a t i s t i c a l a p p ro a c h m e a s u r in g s e l e c t e d v a r i a b l e s o f th e g r a i n s i z e d i s t r i b u t i o n . T he o t h e r , and p e r h a p s more b a s i c m eth o d , c l a s s i f i e s and d e s c r i b e s s e d im e n t s i n te rm s o f t h e i r d o m in a n t c a u s e o f d e p o s i t i o n , m apping s e d i m ents o f s i m i l a r o r i g i n a s a u n i t (Em ery, 1 9 6 0 ) . T h is method o f d e s c r i p t i o n i n e v i t a b l y i n v o l v e s a d i s c u s s i o n o f to p o g r a p h y , s e d im e n t t r a n s p o r t and c h a n g e s w i t h g e o l o g i c a l t i m e . By u se o f th e l a t t e r m ethod t h e s e d im e n t s o f t h e s o u t h e r n C a l i f o r n i a n m a in la n d s h e l f may be g r o u p e d i n t o f i v e b r o a d c a t e g o r i e s : ( 1 ) m odern o r c l a s t i c d e t r i t a l , (2 ) r e l i c d e t r i t a l , ( 3 ) o r g a n i c n o n - d e t r i t a l , ( 4 ) a u t h i g e n - i c n o n - d e t r i t a l , and (5 ) r e s i d u a l n o n - d e t r i t a l (Em ery, 1960; W im b erle y , i n S t e v e n s o n , 19 6 1 ; W im berley, 1 9 6 4 ). The c o m p le x ity o f t h e s e d im e n t d i s t r i b u t i o n o b s e r v e d on th e s h e l f i s due t o th e i n t e r a c t i o n o f a number o f r e l a t e d f a c t o r s , such a s t h e r e l a t i v e r a t e s o f d e t r i t a l s e d i m e n t a t i o n , c o n t r i b u t i o n from th e c o n t i n e n t and p r o d u c t i o n o f o r g a n i c and a u t h i g e n i c n o n - d e t r i t a l s e d im e n ts i n th e s u b m a rin e e n v ir o n m e n t, and t h e i n f l u e n c e o f to p o g r a p h y on s e d im e n t d e p o s i t i o n and t r a n s p o r t . 410 The p r im a r y s o u rc e o f se d im e n t f o r th e c o n t i n e n t a l b o r d e r l a n d , and p a r t i c u l a r l y f o r th e m a in la n d s h e l f , i s th e a d j a c e n t l a n d m ass. The m a jo r c o n t r i b u t i o n o f c l a s t i c d e t r i t a l m a t e r i a l t a k e s p la c e i n th e w i n t e r and s p r i n g . I t i s s tr e a m - b o r n e . D u rin g t h e d r y e r m o n th s, th e m ouths of m o st s tr e a m s a re b lo c k e d by w a v e - b u i l t sand b a r s and b e a c h d e p o s i t s . In th e r a i n y s e a s o n s t h e s e b a r r i e r s a r e b re a c h e d and sw ept away. Wave e r o s i o n o f c l i f f s h a s b e e n c o n s id e r e d a s o u rc e o f a p a r t o f th e d e t r i t a l s e d im e n t, b u t a p p a r e n t l y t h i s ty p e o f c o n t r i b u t i o n i s m inor ( S te v e n s o n , U chupi and G o r s l i n e , 1959; W im berley, i n S te v e n s o n , 1961; AHF:USC, 1 9 6 5 ). Modern d e t r i t a l s e d im e n ts occu p y a b o u t 80 p e r c e n t o f th e s h e l f s u r f a c e ( S te v e n s o n , U chupi and G o r s l i n e , 1 9 5 9 ). Emery (1 9 6 0 ) r e p o r t s th e f o l l o w i n g e s t i m a t e s f o r f o u r s e c t i o n s o f t h e s h e l f : o f f S a n ta B a r b a r a , 95 p e r c e n t ; o f f S a n ta M onica, 53 p e r c e n t , o f f San P e d r o , 87 p e r c e n t and o f f San D ieg o , 78 p e r c e n t . G e n e r a l l y , d e t r i t a l s e d im e n ts a r e composed p r i m a r i l y o f san d and s i l t p a r t i c l e s , and a r e c h a r a c t e r i z e d by a seaw ard d e c r e a s e i n g r a i n s i z e , low c o n t e n t o f c a lc iu m c a r b o n a t e , and f r e s h , u n s t a i n e d g r a i n s (Em ery, 1 9 6 0 ). T h re e san d t y p e s , ( 1) q u a r t z - f e l d s p a r s a n d , ( 2 ) b i o t i t e - q u a r t z - f e l d s p a r s a n d , and (3 ) b i o t i t e sa n d , make up t h e d e t r i t a l com plex on th e s h e l f . A u t h i g e n i c m i n e r a l s a r e r a r e or a b s e n t i n t h e s e t h r e e s a n d s ; th e m ost a b u n d a n t c o n s t i t u e n t o f 411 o r g a n i c o r i g i n i s f o r a m i n i f e r a n t e s t s ( S t e v e n s o n , U chupi and G o r s l i n e , 1 9 5 9 ). A r e a s o f d e t r i t a l s e d im e n t o f t e n form s e a w a rd c o n t i n u a t i o n s o f b e a c h e s (E m ery, 1 9 6 0 ). C l a s t i c d e t r i t a l s e d im e n ts o c c u r seaw ard t o a d e p t h o f 91 m e t e r s on n a rro w s e c t i o n s o f t h e s h e l f . T h i s o c c u r r e n c e h a s b e e n n o t e d on a p a r t o f t h e P o i n t C o n c e p tio n s h e l f and m o st o f t h e lo n g , n a rro w O c e a n s id e s h e l f ; d e t r i t a l s e d i m e n t s , m ixed w ith s h e l l m a t e r i a l , a l s o c o v e r th e s h e l f b e tw e e n La J o l l a and P o i n t Loma. Such r e g i o n s a r e c h a r a c t e r i z e d by a g r a d u a l seaw ard p r o g r e s s i o n fro m c o a r s e t o f i n e s e d i m e n t s . D e t r i t a l s e d im e n ts a l s o b l a n k e t t h e i n n e r p o r t i o n s o f th e w id e s h e l f s e g m e n ts i n c l u d i n g t h e a r e a b e h in d t h e Los A n g e le s H arb o r b r e a k w a t e r , m ost o f t h e S a n ta M onica s h e l f e x c e p t i n g i t s c e n t r a l p l a t e a u , and th e San D iego s h e l f . On th e S a n t a B a r b a r a s h e l f , th e S a n ta C l a r a P r o d e l t a d e p o s i t i s d e t r i t a l i n n a t u r e , and th e Las P i t a s mud d e p o s i t , a w e stw a rd e x t e n s i o n o f t h e P r o d e l t a , i s p r o b a b l y a l s o d e t r i t a l (W im b e rle y , i n S t e v e n s o n , 1961; W im b e rle y , 1 9 6 4 ). I n s p i t e o f th e am ple s u p p l y o f m odern d e t r i t a l ma t e r i a l t o t h e s h e l f and i t s c o n s t a n t t r a n s p o r t o v e r p a r t s o f th e r e g i o n s , e x t e n s i v e a r e a s o f b o tto m a r e c o v e r e d by s e d im e n ts o f o t h e r o r i g i n . Some a r e on t o p o g r a p h i c h i g h s . O th e r a r e a s w h ic h do n o t r i s e above t h e g e n e r a l t o p o g r a p h i c l e v e l p r o b a b l y e s c a p e b l a n k e t i n g by f i n e - g r a i n e d d e t r i t a l m a t e r i a l a s th e r e s u l t o f l o c a l i z e d wave o r c u r r e n t a c t i o n . 4121 The r e l i c d e t r i t a l s e d im e n t d e p o s i t s o f t h e m a in la n d s h e l f f i t t h i s d e s c r i p t i o n . These s e d im e n t s a r e i n th e p r o c e s s o f a d j u s t i n g t o a new e n v i r o n m e n t a l c o n d i t i o n , t h e p r e s e n t h e i g h t o f s e a l e v e l . Some r o c k y a r e a s and d e p o s i t s o f ro u n d e d g r a v e l s a r e r e l i c s o f a lo w e r s e a l e v e l . A r e a s o f t h i s ty p e a r e l o c a t e d on t h e w id e S a n ta M o n ica , S an Pedro and San D iego s h e l v e s . A n c ie n t b e a c h d e p o s i t s , l i t t l e ch a n g e d by r e c e n t d e p o s i t i o n and s u b m e rg e n c e , a l s o re m a in a s e v id e n c e o f P l e i s t o c e n e s t r a n d l i n e s (E m ery, 1960; S t e v e n s o n , U c h u p i and G o r s l i n e , 1959; S te v e n s o n [ b ] , i n S t e v e n s o n , 1 9 6 1 ). The m o st d i s t i n c t i v e r e l i c - s e d im e n t on t h e s o u t h e r n C a l i f o r n i a n m a in la n d i s a c o a r s e r e d s a n d . G r a i n s a r e p r i m a r i l y q u a r t z and f e l d s p a r and a r e c o a te d w i t h v a r y i n g am ounts of i r o n o x id e . Red s a n d , w ith an a v e r a g e m edian d i a m e t e r o f 480 m ic r o n s , i s c o n s i d e r a b l y c o a r s e r t h a n p r e s e n t - d a y d e t r i t a l s e d im e n t s (E m ery, 1 9 6 0 ) . D e p o s i t s o f r e d san d a r e r e s t r i c t e d to th e S a n t a M o n ica , San P e d ro and San D ieg o d i v i s i o n s o f th e m a in la n d s h e l f . W ith p e r h a p s one e x c e p t i o n , t h e d e p o s i t i n t h e c e n t e r o f t h e S an P ed ro s h e l f , th e r e d san d i s th o u g h t t o have b e e n d e p o s i t e d i n a t e r r e s t r i a l o r t r a n s i t i o n a l e n v ir o n m e n t (E m ery, 1960; S t e v e n s o n , U c h u p i and G o r s l i n e , 1959; W im b erley i n S t e v e n so n , 1961; W im b erley , 1 9 6 4 ). W im b erley ( i n S t e v e n s o n , 1961; W im b e rle y , 1964) c l a s s i f i e s th e more r e c e n t l y form ed t r a n s g r e s s i v e s e d im e n ts a s r e l i c . These d e p o s i t s w ere 413 form ed b y th e a c t i o n of a d v a n c in g s u r f a s s e a l e v e l r o s e from i t s fo rm er low s t a n d . T r a n s g r e s s i v e s e d im e n t s , n o t y e t c o v e r e d by r e c e n t d e t r i t a l m a t e r i a l s , a r e found b e tw e e n P o i n t C o n c e p tio n and G a v i o t a , o f f D el Mar and o f f San D iego. N o n - d e t r i t a l o r g a n i c s a n d s , form ed p r i m a r i l y o f th e c a l c a r e o u s and s i l i c e o u s r e m a in s o f p r o t e s t s and m e ta z o a n i n v e r t e b r a t e s , o c c u r a t s c a t t e r e d l o c a t i o n s on th e s h e l f . Such s e d im e n ts g e n e r a l l y form w here th e d e p o s i t i o n a l r a t e o f d e t r i t a l m a t e r i a l i s low . A re a s o f o r g a n i c sa n d s com po sed p r i m a r i l y o f m o llu s c a n d e b r i s o f t e n d e v e l o p n e a r s h o re and a ro u n d h e a d l a n d s w h ere s t r o n g c u r r e n t a c t i o n r e t a r d s d e t r i t a l d e p o s i t i o n . S ands composed o f f o r a m i n i f e r a l t e s t s a r e common on th e o u t e r p a r t s o f th e s h e l f w here d e t r i t a l d e p o s i t i o n a l r a t e s a r e low due t o t h e d i s t a n c e d e t r i t a l m a t e r i a l o f c o n t i n e n t a l o r i g i n m ust be t r a n s p o r t e d from i t s s o u r c e . S h e l l sa n d i s a d o m in a n t ty p e o n ly i n th e San D ieg o a r e a . E ls e w h e re on t h e s h e l f i t i s o f n e g l i g i b l e i m p o r t a n c e . O n ly two s m a l l p a t c h e s o f s h e l l san d h av e b e e n d e t e c t e d on t h e m a in la n d s h e l f n o r t h o f P o i n t Dume. S e v e r a l s m a l l p a t c h e s o c c u r on th e S a n t a M o n ica and San P e d ro s h e l v e s . B etw een New port and La J o l l a t h i s t y p e o f s e d i ment i s n e a r l y a b s e n t fro m t h e s h e l f ( S t e v e n s o n , U chupi and G o r s l i n e , 1959; Em ery, 1960; U c h u p i, i n S t e v e n s o n , 1 9 6 1 ). Two t y p e s o f n o n - d e t r i t a l a u t h i g e n i c s e d im e n t s , g l a u c o n i t i c and p h o s p h o r i t i c s a n d s , o c c u r on th e m a in la n d s h e l f . The p rim e m i n e r a l c o n s t i t u e n t o f e a c h o f t h e s e 414 s a n d s fo rm s c h e m i c a l l y i n o x i d a t i n g s u b m a r in e e n v i r o n m e n ts .! B oth p h o s p h o r i t e and g l a u c o n i t e a r e common n e a r th e o u t e r edge o f th e s h e l f w h ere w a t e r m o tio n i s s t r o n g and d e t r i t a l d e p o s i t i o n a l r a t e s a r e low . D e p o s i t s a r e a b s e n t fro m t h e n a rro w p o r t i o n o f t h e s h e l f and th e i n n e r p a r t s o f th e w id e r s h e l f s e g m e n ts b e c a u s e m a n t l i n g by m odern d e t r i t a l s e d im e n ts h a s d i l u t e d o r p r e v e n t e d t h e i r a c c u m u l a t i o n . Ap p r e c i a b l e q u a n t i t i e s o f g l a u c o n i t e a r e fo u n d o f f S a n ta B a r b a r a , i n S a n ta M o n ica Bay and o f f San D ie g o . G l a u c o n i t i c s a n d s a r e a b s e n t fro m th e San P e d ro Bay s h e l f . P h o s p h o r i t e c o n t a i n i n g s a n d s a r e l i m i t e d , b e i n g p r i m a r i l y l o c a t e d i n S a n t a M onica Bay (E m ery, 1960; S te v e n s o n , U chupi and G o r s l i n e , 1959; S te v e n s o n l b ] , i n S t e v e n s o n , 1 9 6 1 ). N o n - d e t r i t a l r e s i d u a l s e d im e n t s a r e t h e p r o d u c t s o f w e a t h e r i n g and e r o s i o n o f su b m a rin e b e d r o c k . They o c c u r a t many l o c a l i t i e s on th e m a in la n d s h e l f b u t a r e i n v a r i a b l y p r e s e n t w here b e d r o c k i s e x p o se d on t h e b o tto m . R e s i d u a l s e d im e n ts o c c u r b e tw e e n G a v i o t a and G o l e t a , on t h e c e n t r a l p l a t e a u i n S a n t a M onica Bay and on t h e San P e d ro Bay s h e l f (W im b e rle y , i n S t e v e n s o n , 1961; W im b e rle y , 1964; Em ery, 1 9 6 0 ). D e t r i t a l s e d im e n t c o n t r i b u t e d by s t r e a m s to b e a c h e s and t h e i n n e r s h e l f u n d e r g o e s t r a n s p o r t a l o n g , on and a c r o s s th e s h e l f . Wave a c t i o n p r o v i d e s th e p rim e m o tiv e f o r c e and to p o g ra p h y p r o f o u n d l y i n f l u e n c e s t h e outcome o f such m ovem ent. Emery (1 9 6 0 ) d e s c r i b e s t h i s p r o c e s s ; 4 1 5 ; Once on th e b e a c h , th e s e d im e n t comes u n d e r th e i n f l u e n c e o f w a v e s. The c o n s t a n t movement e v e n t u a l l y b r e a k s up th e g r a i n s , and th e f i n e d e b r i s i s c a r r i e d se a w a rd . B e fo re b e in g l o s t to th e s e a , th e san d i s moved a lo n g th e s h o re f o r g r e a t d i s t a n c e s by w a v e s. Where w aves s t r i k e _ t h e b e a c h d i a g o n a l l y , th e y ru n up th e b e a c h and down a g a in a t a p o i n t a few f e e t f u r t h e r a lo n g t h e b e a c h . As a r e s u l t of t h i s n e t lo n g s h o r e w a te r movement, some sand i s t r a n s p o r t e d a lo n g t h e b e a c h - Cpp- 2 5 -6 ) S ed im en t t r a n s p o r t a lo n g th e b e a c h e s t a k e s p la c e i n s e v e r a l w e l l - d e f i n e d " c e l l s ” or se g m e n ts o f th e s h e l f (Em ery, 1960, F i g u r e 2 8 ) . T hese g e o g r a p h ic u n i t s a r e d e l i m i t e d by t o p o g r a p h ic f e a t u r e s , p r i n c i p a l l y su b m arin e c a n y o n s. S ed im en t moved by w a v e - g e n e r a te d lo n g s h o r e d r i f t t r a v e l s s o u t h w i t h i n su c h a " c e l l ” u n t i l i t i s f i n a l l y tr a p p e d b y th e su b m a rin e canyon t h a t t r a n s e c t s t h e s h e l f a t th e s o u t h e r n b o u n d a ry . O nly m inor le a k a g e o f sa n d t a k e s p la c e fro m one segm ent to th e n e x t a c r o s s t h e s e su b m a rin e canyons (Em ery, 1960; S te v e n s o n , Uchupi and G o r s l i n e , 1959; AHF:USC, 1 9 6 5 ). " D e t r i t a l s e d im e n ts i n th e n e a r s h o r e p a r t s o f th e m a in la n d s h e l f a l s o r e s e m b le th e b e a c h e s i n t h e i r m o b i l i t y " (Em ery, 1960, p . 1 0 4 ). D e f i n i t e w a v e - g e n e r a te d c u t and f i l l a c t i v i t y t o d e p t h s o f 10 m e te r s h as been r e p o r t e d , b u t most o f t h e s e c h a n g e s o c c u r i n w a te r o f l e s s e r d e p t h s (Emery, 1 9 6 0 ). The s e d im e n t f i n e r th a n c o a r s e s i l t i s h e l d i n s u s p e n s io n b y waves and c u r r e n t s and i s moved s e a w a rd . M ost o f t h i s f i n e - g r a i n e d m a t e r i a l s e t t l e s on th e s l o p e s and i n 416 th e b a s i n s . Some p a r t i a l l y m ask s and f i l l s t h e i n t e r s t i c e s o f t h e c o a r s e r s e d im e n ts on t h e o u t e r p a r t s o f t h e s h e l v e s . Some f i l l s d e p r e s s i o n s i n t h e s h e l f s u r f a c e w h ich a r e b e lo w t h e d e p th o f n o rm a l wave and c u r r e n t a c t i o n . Some i s t r a p p e d by s u b m a rin e t o p o g r a p h i c h i g h s , su c h a s t h e r i d g e l i k e C a r p e n t e r i a S h e l f - r i s e , t o form d e p o s i t s o f f i n e s e d i m e n ts i n r e l a t i v e l y s h a ll o w d e p t h s ( S t e v e n s o n , U chupi and G o r s l i n e 1.959; S te v e n s o n [b ] , i n S t e v e n s o n , 1961; W imber l e y , i n S t e v e n s o n , 1961; W im b erle y , 196 4 ; and AHFrUSC, 1 9 6 5 ). The G e n e r a l T e x tu r e o f t h e S h e l f S e d im e n ts U n c o n s o l i d a t e d s h e l f s e d im e n ts c o n s i s t o f a m i x t u r e o f i n d i v i d u a l g r a i n s t h a t may ra n g e fro m l e s s t h a n a m ic ro n t o s e v e r a l m i l l i m e t e r s i n d i a m e t e r . G e o l o g i s t s u se a num b e r o f s t a t i s t i c a l p r o c e d u r e s t o d e s c r i b e t h i s s o r t o f " p a r t i c u l a t e p o p u l a t i o n . " The s i m p l e s t s t a t i s t i c a l m ethod o f s e d im e n t d e s c r i p t i o n i n v o l v e s t h e u se o f a r b i t r a r y l i m i t s t o d i v i d e t h i s t h e o r e t i c a l p a r t i c l e s i z e c o n tin u u m i n t o a number o f c l a s s e s or " s i z e g r a d e s . " I n t h e W entw orth ( 1 9 2 2 , c i t e d i n K rum bein and P e t t i j o h n , 1939) s i z e c l a s s i f i c a t i o n g e n e r a l l y em ployed i n A m erican g e o lo g y th e g ra d e u n i t s o f ( 1 ) g r a v e l , w ith d i a m e t e r s b e tw e e n 2 and 4 mm; ( 2 ) s a n d , w i t h d ia m e t e r s : b e tw e e n 2 and 0 .0 6 2 mm; ( 3 ) s i I t , b e tw e e n 0 .0 6 2 and 0 .0 0 4 417: mm; and ( 4 ) c l a y , b elo w 0 .0 0 4 mm were s u f f i c i e n t t o i n c l u d e : th e p a r t i c l e r a n g e o f m ost o f th e s a m p le s c o l l e c t e d from th e m a in la n d s h e l f . L a r g e r p a r t i c l e s , p e b b l e s , c o b b le s and b o u l d e r s , were g ro u p e d t o g e t h e r and n o t e d o n ly a s r o c k . S am ples c o n t a i n e d v a r i o u s p e r c e n t a g e s o f some o r a l l o f t h e g ra d e s i z e s , g r a v e l , s a n d , s i l t and c l a y (K rum bein and P e t t i j o h n , 1 9 3 8 ). O nly 7 p e r c e n t o f t h e s a m p le s c o l l e c t e d fro m th e m a in la n d s h e l f c o n t a i n e d g r a v e l . A bout h a l f o f t h e s e sam p l e s h ad l e s s t h a n 5 p e r c e n t by w e i g h t . The l a r g e s t p r o p o r t i o n o f g r a v e l i n a sa m p le was 29 p e r c e n t . G r a v e l i s n o t c o n s i d e r e d a t y p i c a l c o n s t i t u e n t o f m a in la n d s h e l f s e d im e n ts (W im b e rley , i n S t e v e n s o n , 1961; W im b erle y , 1964; AHF: USC, 1 9 6 5 ). N e a r l y 30 p e r c e n t o f th e s a m p le s had a sa n d c o n t e n t o f more t h a n 80 p e r c e n t (A p p en d ix F ig u r e C - 3 ) . T h is g ro u p o f s a m p le s i n c l u d e s a d i s p r o p o r t i o n a t e l y g r e a t number o f s h a l l o w w a t e r s a m p le s w i t h sand c o n t e n t v a l u e s o f more th a n 90 p e r c e n t . A t th e o t h e r e x tre m e i s a s i m i l a r number o f s a m p le s o f low ( l e s s t h a n 10 p e r c e n t ) sand c o n t e n t t h a t w ere c o l l e c t e d fro m th e s h e l f o f f S a n ta B a r b a r a . Betw een t h e s e two g ro u p s a t t h e e x tr e m e s o f t h e r a n g e , t h a t i s , b e tw een 10 p e r c e n t and 90 p e r c e n t s a n d , sa m p les d i s t r i b u t e r a t h e r u n i f o r m l y by 10 p e r c e n t i n t e r v a l u n i t s (W im b erley i n S t e v e n s o n , 1961, F i g u r e 36; W im b erle y , 1964, F i g u r e 40; AHF:USC, 1965, F i g u r e 4 . 6 ) . APPENDIX PIGURE C -3 A H is to g r a m o f Sand C o n te n t Show ing th e P e r c e n t o f th e T o t a l Sam ples i n E ach 10 p e r c e n t I n c r e m e n t o f Sand Con t e n t . ( F i g u r e 40, W im b erley , 1964; and i n F ig u r e 4 . 6 , AHFtUSC, 1 9 6 5 ). 4 1 8 419 Figure C-3 4 0 36 32 (A UJ 0. 2 < (A 24 _i < l- o I - z I L i o a: U J C L 0 10 20 30 4 0 50 60 7 0 80 90 100 PERCENT OF SAND CONTENT 420 The p e r c e n t a g e d i s t r i b u t i o n f o r e a c h 10 p e r c e n t s i l t i n t e r v a l i s r e l a t i v e l y u n ifo r m , v a r i a t i o n from 7 p e r c e n t to 12 p e r c e n t o f s a m p le s , up t o th e 90 p e r c e n t l e v e l (A p p en d ix F ig u r e C - 4 ) . A lm ost o n e - q u a r t e r o f th e sam p les have s i l t c o n t e n t s o f l e s s th a n 10 p e r c e n t . Most o f t h e s e sam p les w ere c o l l e c t e d fro m th e n e a r s h o r e r e g i o n o f th e s h e l f and i n a c o a r s e to medium r e d san d d e p o s i t on th e San D iego s h e l f (W im b erley i n S te v e n s o n , 1961, F ig u r e 41; Wim b e r l e y , 1964, F i g u r e 45; AHFrUSC, 1965, F ig u re 4 . 7 ) . In c o n t r a s t to sam ple sand and s i l t c o n t e n t v a l u e s , t h a t v a r y o v er t h e e n t i r e ra n g e fro m 0 to 100 p e r c e n t , th e h i g h e s t p r o p o r t i o n o f c l a y i n a sam ple was 52 p e r c e n t . M ost sa m p le s c o n t a i n e d l e s s th a n 16 p e r c e n t c l a y (A p p en d ix F ig u r e C - 5 ) . O ver a t h i r d o f th e sa m p le s a n a ly z e d had c l a y c o n t e n t s low er t h a n 2 p e r c e n t . T hese sa m p le s w ere c o l l e c t e d i n a r e a s o f c u r r e n t n o n - d e p o s i t i o n (W im berley i n S te v e n s o n , 1961, F ig u r e 46; W im berley, 1964, F ig u re 50; AHFrUSC, 1965, F i g u r e 4 . 8 ) . The d i s t r i b u t i o n o f s e d im e n t t y p e s may be mapped by s im p ly u s i n g p e r c e n t a g e v a l u e s f o r g r a v e l , s a n d , s i l t , or c l a y , b u t more f r e q u e n t l y s e d im e n t t y p e s a r e combined i n a T r i a n g u l a r S e d im e n t D iagram . The f i g u r e a c t u a l l y r e p r e s e n t s one f a c e o f a t e t r a h e d r o n , whose c o r n e r s a r e 100 p e r c e n t g r a v e l , s a n d , s i l t and c l a y . O nly t h r e e o f t h e s e s e d im e n t t y p e s can be u t i l i z e d i n one t r i a n g l e . T y p i c a l l y T r i a n g u l a r D iagram s a r e d i v i d e d i n t o 12, a r e a s r e p r e s e n t i n g j APPENDIX FIGURE C-4 A H is to g r a m o f S i l t C o n te n t Showing th e P e r c e n t o f th e T o t a l S am p les i n E ach 10 p e r c e n t I n c r e m e n t o f S i l t Con t e n t . ( F i g u r e 45, W im b erle y , 1964; and i n F i g u r e 4 . 7 , AHFrUSC, 1 9 6 5 ). 421 422 Figure C-4 C O U1 C O l& J o tr UJ O L 4 0 36 I 32 I £ 28 < I 24 O 20 l- 16 I 12 I 8 I 4 I 0 0 10 20 30 4 0 50 60 70 80 9 0 100 PERCENT OF SILT CONTENT APPENDIX FIGURE C-5 A H is to g ra m o f C lay C o n te n t Showing th e Per c e n t o f th e T o t a l Sam ples i n Each 2 p e r c e n t I n c re m e n t o f C la y C o n te n t. ( F ig u r e 50, W im berley, 1964; and i n F ig u r e 4.8'^’ AHF:USC, 1 9 6 5 ). 423 PERCENT O F T O T A L SAMPLES 424 Figure C-5 40 3 6 32 28 24 20 0 2 4 6 8 10 12 1 4 16)16 PERCENT OF CLAY CONTENT 425 p a r t i c u l a r c o m b in a tio n s o f a p a r t o f t h e p e r c e n t i l e r a n g e o f t h e m a jo r g r a d e s i z e s ; t h e s e a re g i v e n d e s c r i p t i v e names: su ch a s san d y s i l t y g r a v e l (Em ery, 1 9 6 0 , F i g u r e 1 7 7 ). Once t h e g r a d e s i z e p e r c e n t a g e s a r e known f o r a sa m p le , i t s s e d im e n t ty p e c a n e a s i l y b e d e t e r m i n e d , a s t h e r e i s b u t one p o s s i b l e l o c a t i o n o n th e t r i a n g l e d ia g r a m f o r any c o m b in a tio n o f t h r e e v a lu e s (Em ery, 1 960, F ig u r e 177; S te v e n s o n , U ch u p i and G o r s l i n e , 1959; W im b erle y i n S t e v e n s o n , 1961; AHF:USC, 1 9 6 5 ) . By co m b in in g s u i t a b l e m o d i f i e r s i n d i c a t i n g c o l o r an d c o m p o s itio n w i t h th e t e x t u r a l name, s u c h a s o l i v e g r e e n m ic a c e o u s sandy s i l t , t h e d e s c r i p t i v e s y s te m b a s e d on t h e t r i a n g l e d ia g r a m may be e x p a n d e d . I n t h e i r a n a l y s i s o f the s h e l f s e d im e n ts S t e v e n so n , U chupi and G o r s l i n e ( 1 9 5 9 , F i g u r e 6) u s e d t h e " g r a v e l - s a n d - s i l t 7 1 f a c e o f th e t e t r a h e d r o n f o r t h e i r t r i a n g l e d i a gram (A p p e n d ix F i g u r e C -6) ; W im berley ( i n S t e v e n s o n , 1961, F ig u r e 6 ; W im b e rle y , 1964, F ig u r e 6 ; AHF:USC, 1965, F i g u r e 4 . 1 ) , on t h e o t h e r h and, u s e d the 7 ts a n d - s i l t - c l a y " t r i a n g l e and com bined th e g r a v e l f r a c t i o n w i t h th e s a n d f r a c t i o n f o r th e s a m p le s c o n t a i n i n g th e fo rm er f r a c t i o n . I n s p i t e o f t h e f a c t t h a t t h e i r p r e s e n t a t i o n i s somewhat p r e l i m i n a r y and b a s e d on f e w e r s a m p le s , th e d e s c r i p t i o n o f t h e n a t u r e an d d i s t r i b u t i o n o f t h e s e d im e n t ty p e s on t h e m a in la n d s h e l f p r e s e n t e d by S t e v e n s o n , U ch u p i and G o r s l i n e ( 1 9 5 9 , F i g u r e s 12, 17 and 20, B o tto m M a t e r i a l ; A p p e n d ix F i g u r e s C -7 , C-8 an d C-9) a p p e a r s t o be a m ore APPENDIX FIGURE C-6 A G r a v e l - S a n d - S i I t S edim ent-T ype T r i a n g u l a r Diagram w i t h D e s c r i p t i v e Names ( F ig u r e 6 , S te v e n s o n , U chupi and G o r s l i n e , 1 9 5 9 ). 426 427 Figure C-6' t o o - g - 'g r a v e l SANDY SILTY GRAVEL SANDY GRAVELLY SILT SILTY GRAVELLY SAND SANDY SILT SILTY SAND SO APPENDIX FIGURE C-7 A r e a l D i s t r i b u t i o n o f Bottom M a t e r i a l on th e N o r th e rn S e c t i o n o f th e M a in la n d S h e l f ( P o i n t A r g u e l l o t o P o i n t Dume) ( F ig u r e 12, S te v e n s o n , U chupi and G o r s l i n e , 1 9 5 9 ). 428 P I ARGUELLO TO PT DUME BOTTOM MATERIAL PT. CONCEPTION SHELF F ig u r e C-7 ■ p * C O V O APPENDIX FIGURE C-8 Areal Distribution of Bottom Materials on the Central Section of the Mainland Shelf (Point Dume to Corona del Mar) (Figure 17, Stevenson, Uchupi and Gorsline, 1959). 430 P I DUME TO CORONA DEL MAR BOTTOM M A TERIA L M A T U T C M IU tft F O O T CO M TO VO LEGEND B O C K , G R A V E L £ (= ■SHELL F R A G M E N T S L I O LIV E G R E E N I S IL T Y SA N D H ! SANDY G R A V E L BLA CK SANDY S IL T SANDY S IL T O L IV E G R E E N SANDY S IL T M JT L T U » T 114. M O N IC A l i m tu m HOCK. 6 R A V E L S H E L L IL 1C 4U H S O i i S GRAVELLY SAND c r s . t o f i n e RED SAN D SL A U C O MED. T O V ERY , FINE O LIV E G R E E N SAND LOM G U A C H B L A C K S E P L A N T . D E B R IS OLIVE G R E E N S IL T F ig u r e C-8 S L A U C O N IT E - 302 50' 40' 30' 20' S A N PEDRO SHELF' 1 0 ' -B O C K , 6 R A V E L A N D S N E L L F R A & 1 1 8 ° 50' 30' APPENDIX FIGURE C-9 Areal Distribution of Bottom Materials on the Southern Section of the Mainland Shelf (Corona del Mar to San Diego) (Figure 20, Stevenson, Uchupi and Gorsline, 1959). 432 CORONA DEL MAR TO SAN DIEGO BOTTOM MATERIAL L£6£M O OftAVCL « S H E L L M A 4M C M T* M S TO e u « r a y s a n d Q ] p IHK o l i v e t f t t C N SAND 1 — I OLIVE O f tf tN SlL T V SAND EE3 o l i v e M I E N SANDY SILT 117° 3 0 ‘ r e a l i s t i c a p p r o x i m a ti o n o f m a in la n d s h e l f s e d im e n t d i s t r i b u t i o n a l p a t t e r n s th a n t h a t d e v e lo p e d b y W im berley ( i n S te v e n s o n , 1 9 6 1 , F i g u r e s 7 -1 0 ; W im berley, 1964, F i g u r e s 7 - 1 0 ; AHF:USC, 1965, F i g u r e s 4 - 2 - 4 . 5 ) i n h i s l a t e r and more c o m p le te a n a l y s i s . T h i s i s p a r t i c u l a r l y tr u e fro m the s t a n d p o i n t o f d e s c r i b i n g th e v a r i a b i l i t y of s u b s t r a t e t y p e s a v a i l a b l e to t h e b e n t h i c m a c ro fa u n a o f t h e s h e l f . For e x a m p le , s u b l i t t o r a l r o c k c o v e r s 5 .1 p er c e n t o f t h e a r e a o f t h e s h e l f ( J o n e s [ c ] , i n S te v e n s o n , 1 9 6 1 ) . The d i s t i n c t i o n b e tw e e n a ,rr o c k y b o tto m " and a " s o f t b o tto m " i s r a t h e r b a s i c e c o l o g i c a l l y ; t h e f a u n i s t i c p o t e n t i a l o f t h e s e two h a b i t a t s i s q u i t e d i f f e r e n t . W im berley ( i n S te v e n s o n , 1961; W im berley 1964) f a i l s t o in c lu d e r o c k and c o a rs e f r a c t i o n t y p e s i n h i s c l a s s i f i c a t i o n o f s e d im e n t t y p e s , and c o n s e q u e n t l y h i s i l l u s t r a t i o n s o f such complex a r e a s a s th e c e n t r a l s h e l f p r o j e c t i o n i n S a n t a M onica Bay, t h e San P e d ro Bay s h e l f and t h e San Diego s h e l f are q u i t e m i s l e a d i n g . W im b e rle y Ts s e d im e n t p a t t e r n s f o r t h e s e a r e a s a r e much s i m p l e r th a n th e y r e a l l y a r e . C o n v e r s e ly , h i s i l l u s t r a t i o n s ten d t o c r e a t e a p i c t u r e o f c o m p le x ity i n a r e a s s u c h a s t h e long an d n a rro w P o in t C o n c e p tio n and O c e a n s id e s h e l v e s t h a t S te v e n s o n , U chupi and G o r s l i n e (1 9 5 9 ) p o r t r a y a s h a v in g r e l a t i v e l y s im p le s e d im e n t p a t t e r n s . W im berley shows th e s e a r e a s as p a tc h y , r a t h e r t h a n banded i n a r e l a t i v e l y r e g u l a r m anner. W im berley d o e s p r o v id e d e t a i l e d i n f o r m a t i o n i n t h e d i s t r i b u t i o n o f such s e d im e n t p a r a m e t e r s as m ed ian d i a m e t e r s , s o r t i n g and sk ew n ess o f e a c h s h e l f r e g io n a s w e ll a s mean v a l u e s f o r th e s h e l f as a u n i t . The d e s c r i p t i o n s o f th e s h e l f s e d im e n ts u n d e r t a k e n i n t h i s p a p e r combine t h e i n f o r m a t i o n c o n ta in e d i n t h e s e two s o u r c e s , r e l y i n g on S te v e n s o n , Uchupi and G o r s l i n e (1 9 5 9 ) f o r t h e i r d e s c r i p t i o n o f s e d im e n t t y p e s and on W im berley ( i n S te v e n s o n , 1961; W im berley, 1964) f o r h i s m e a su re m e n ts o f q u a n t i t a t i v e s e d im e n ta r y p a r a m e t e r s ; n e a r l y a l l o f W im b e rle y 1s d i s c u s s i o n i s r e p e a t e d i n AHPrUSC, ( 1 9 6 5 ) . The s h e l f s a m p le s a n a ly z e d by W im berley ( i n S te v e n so n , 1961; W im berley, 1964) ra n g e d fro m 100 p e r c e n t sand to 100 p e r c e n t s i l t ; th e d i s t r i b u t i o n o f th e s a m p le s by s e d im e n t t y p e s i s as f o l l o w s : 27 per c e n t s a n d , 25 p e r c e n t s i l t y s a n d , 23 p e r c e n t san d y s i l t , and 14 p e r c e n t s i l t . I n o n ly 12 p er c e n t o f th e sa m p le s d i d th e c o n c e n t r a t i o n o f c l a y - s i z e d g r a i n s e x c e e d 10 p e r c e n t . As t h e s e s a m p le s were d i s t r i b u t e d i n t h r e e t r i a n g l e d ia g ra m c a t e g o r i e s , c la y e y s i l t , c la y e y san d y s i l t , and c f a y e y s i l t y s a n d , W im berley g ro u p ed them i n t o one c a t e g o r y , " c l a y e y s e d im e n ts " t o i n d i c a t e sam p les t h a t c o n t a i n e d 10 p e r c e n t or more c l a y . Only 7 p e r c e n t o f th e sa m p le s c o n t a i n e d g r a v e l , and a b o u t h a l f o f t h e s e had l e s s th a n 5 p e r c e n t g r a v e l - The a r e a o f t h e m a in la n d s h e l f c o v e re d by e a c h o f th e s e d im e n t t y p e s d e te r m in e d b y th e t r i a n g l e d ia g ra m m e th od ( s a n d - s i l t - c l a y ) i s a s f o l l o w s : 22 p e r c e n t s a n d , 30 p e r c e n t s i l t y s a n d , 24 p e r c e n t san d y s i l t , 16 p e r c e n t 436" s i l t and 8 p er c e n t c l a y e y s e d im e n t s . T h is a n a l y s i s r e v e a l s t h a t th e t y p i c a l s h e l f s e d im e n t i s a t t h e b o u n d a ry b e tw e e n sandy s i l t and s i l t y s a n d ; and t h a t i t c o n t a i n s a l most e q u a l q u a n t i t i e s o f sa n d and s i l t g r a i n s p l u s l e s s th a n 10 p e r c e n t c l a y (W im b erley i n S te v e n s o n , 1961; Wim b e r l e y , 1964, T a b le 1; and i n AHF:USC, 1 9 6 5 ). S e d im e n ts can be c h a r a c t e r i z e d by t h e m ed ian g r a i n s i z e ( i n t e r m e d i a t e d i a m e t e r ) or o t h e r m e a s u re m e n ts o f c e n t r a l t e n d e n c y . The m ed ian d i a m e t e r i s t h e g r a i n s i z e d i v i d i n g a sam ple i n t o two e q u a l f r a c t i o n s . V a lu e s f o r s h e l f s a m p le s c o l l e c t e d d u r i n g t h i s s u r v e y ra n g e d fro m 0 .0 0 7 t o 0 .6 2 5 mm (A p p e n d ix F ig u r e C -1 0 ). O ver a t h i r d , 37 per c e n t, o f t h e s e s a m p le s had m ed ian d i a m e t e r s w i t h i n t h e ra n g e o f th e v e r y f i n e sa n d g ra d e c l a s s , 0 .1 2 5 to 0 .0 6 2 mm. N e a r l y as many, 35 p e r c e n t , f e l l w i t h i n t h e l i m i t s o f c o a r s e s i l t , 0 .0 6 2 t o 0 .0 3 1 mm. Sam ples w i t h m edian d i a m e t e r s g r e a t e r t h a n 0 .1 2 5 mm o r l e s s t h a n 0 .0 3 1 mm a c c o u n te d f o r o n ly 27 p e r c e n t o f t h e t o t a l a n a l y z e d . C o a rs e s e d im e n ts o ccu r i n num erous p a t c h e s s c a t t e r e d t h r o u g h o u t th e s h e l f , b u t t h e y a r e m ost common on th e w id e San D ieg o s h e l f . S e d i m e n ts h a v in g t h e s m a l l e s t m edian d i a m e t e r s a r e l o c a t e d a t i n t e r m e d i a t e d e p t h s on t h e s h e l f b e tw e e n S a n t a B a r b a r a and V e n tu r a (W im b e rle y , i n S t e v e n s o n , 1961, F i g u r e 11; W imber l e y , 1 9 6 4 , F i g u r e 11; AHF:USC, 1 965, F ig u r e 4 . 9 ) . At many p l a c e s on t h e s h e l f t h e r e i s a p r o g r e s s i v e se a w a rd d e c r e a s e i n m edian d i a m e t e r from f i n e or v e r y f i n e sa n d n e a r s h o re APPENDIX FIGURE C-10 A H is to g r a m o f G ra in S iz e Showing t h e P e r c e n t o f th e T o t a l S a m p le s f o r Each M edian D ia m e te r I n c r e m e n t . ( F i g u r e 11, W im b erle y , 1965; and i n F ig u r e 4 . 9 , AHFrUSC, 1 9 6 5 ). 437 Figure C-10 4 0 36 32 Q . 28 2 4 0 0 8 >5 .5 .25.125.062O3L0I6.008 MEDIAN DIAMETER-MM. 439 to c o a r s e s i l t i n d e e p e r w a t e r . I n o t h e r a r e a s th e d i s t r i b u t i o n o f m edian d i a m e t e r s d o e s n o t conform t o t h i s g e n e r a l p a t t e r n (W im berley, i n S te v e n s o n , 1961, F ig u r e 11; W imber l e y , 1964, F ig u r e 11; AHF:USC, 1965, F ig u r e 4 . 9 ) . T h e re i s a r e l a t i o n s h i p b e tw e e n m edian d ia m e te r and s o r t i n g c o e f f i c i e n t . S e d im e n ts w i t h m edian d i a m e t e r s o f a b o u t 0 .0 6 2 mm have some te n d e n c y to b e s t s o r t i n g ( l o w e s t s o r t i n g c o e f f i c i e n t s ) . As m edian d i a m e t e r s p r o g r e s s i v e l y d e c r e a s e b e lo w 0.062 mm, s e d im e n ts a r e more p o o r l y s o r t e d (h a v e h ig h e r s o r t i n g c o e f f i c i e n t s ) . As m edian d i a m e t e r s i n c r e a s e above 0 .0 6 2 mm (become c o a r s e r ) t h i s ty p e o f p r o g r e s s i v e r e l a t i o n s h i p b e tw e e n s o r t i n g c o e f f i c i e n t and m ed i an d ia m e te r i s l e s s d e f i n i t e . S in c e t h e m a j o r i t y o f t h e s a m p le s c o l l e c t e d from th e m a in la n d s h e l f have m edian d i a m e te r s a t o r n ear t h e s a n d - s i l t l i m i t ( 0.062 m i l l i m e t e r s ) , i t i s n o t s u r p r i s i n g t h a t m ost s o r t i n g c o e f f i c i e n t s a r e w i t h i n th e w e l l - s o r t e d c a t e g o r y , 1 .0 0 t o 2 .5 0 . E x c e p t f o r a few s c a t t e r e d l o c a l i t i e s , r e p r e s e n t e d by b u t one o r two s a m p le s , m o d e r a t e l y s o r t e d ( 2 . 5 0 - 4 . 0 0 ) o r p o o r l y s o r t e d ( g r e a t e r th a n 4 .0 0 ) s e d im e n ts a r e c o n f in e d to o n ly t h r e e r e g i o n s on th e s h e l f : th e w e s t e r n p o r t i o n o f th e S a n ta B a r b a r a s h e l f , c o i n c i d e n t w i t h l a r g e a r e a s o f f i n e s e d im e n t; th e c e n t r a l s h e l f p l a t e a u i n S a n ta M onica Bay i n a r e a s o f c o a r s e s e d im e n t; and a t two l o c a l i t i e s on th e San P e d ro Bay s h e l f (W im berley, i n S te v e n s o n , 1961, F i g u r e s 1 6 -1 9 ; Wim b e r l e y , 1964, F i g u r e s 1 3 - 1 7 ) . 440 The m edian d ia m e te r o f a s e d im e n t w i l l c o i n c i d e w i t h th e m i d - p o i n t b e tw e e n th e q u a r t i l e s (Q-^ = 2 5 th p e r c e n t i l e ; Q3 = 75t h p e r c e n t i l e ) , or any two p e r c e n t i l e s o f th e c u m u la tiv e c u rv e t h a t t o t a l 100 p e r c e n t , i f th e c u rv e o f s e d im e n t s i z e d i s t r i b u t i o n i s s y m m e tr ic a l. Asymmetry o f d i s t r i b u t i o n a b o u t t h e m edian i s term e d skew ness ( S k ) . An a s y m m e tr ic a l o r skewed s i z e cu rv e r e s u l t s when a s m a ll e x c e s s o f s e d im e n t o c c u r s i n one o f th e p a r t i c l e s i z e f r a c t i o n s s u f f i c i e n t i n m a g n itu d e t o ca u se a d e p a r t u r e from th e n o rm a l c u rv e w i t h o u t a p p r e c i a b l y a l t e r i n g t h e m edian d ia m e t e r (K rum bein and P e t t i j o h n , 1 9 3 8 ). Skew ness h a s b een m easured by a number o f m ethods (K rum bein and P e t t i j o h n , 1 9 3 8 ). W im berley ( i n S te v e n s o n , 1961; W im b erley , 1964) a n a ly z e d t h i s v a r i a b l e u s in g th e p h i q u a r t i l e sk ew n ess (S k q ^) m easure w h e re : Skq^ = 1 /2 l o g 2 ( l / Q ^ / M d 2 ) R e s u l t i n g v a l u e s a r e e i t h e r p o s i t i v e or n e g a t i v e ; n e g a t i v e v a l u e s i n d i c a t e an e x c e s s o f c o a r s e s i z e d m a t e r i a l and p o s i t i v e v a l u e s i n d i c a t e an e x c e s s o f f i n e m a t e r i a l . W imber l e y com puted skew ness from th e 1 6 th and 8 4 th p e r c e n t i l e s , f i r s t p h i s k e w n e ss , and th e 5 th and 9 6 th p e r c e n t i l e s , s e c ond p h i s k e w n e ss. R e s u l t s from t h e f i r s t ph i skew ness c a l c u l a t i o n s i n d i c a t e : ( 1) t h a t r e l a t i v e l y few s h e l f sa m p le s have s t r o n g l y n e g a t i v e v a l u e s ( > - 0 . 4 0 ) ; ( 2 ) t h a t most sam p l e s have w e a k ly p o s i t i v e skew ness ( 0 .0 0 to 0 . 4 0 ) ; and ( 3 ) 27 p e r c e n t o f s h e l f sam p les have s t r o n g l y p o s i t i v e skew ness ( g r e a t e r th a n 0 . 4 0 ) . Second p h i skew ness h a s a s i m i l a r c o n c e n t r a t i o n o f p o s i t i v e v a l u e s : 33 p e r c e n t a re w eak ly p o s i t i v e ( 0 .0 0 t o 0 . 9 0 ) and 50 p e r c e n t o f a l l sam p l e s a r e s t r o n g l y p o s i t i v e ( g r e a t e r t h a n 0 . 9 0 ) . Only 20 p e r c e n t o f th e sa m p les h ad n e g a t i v e v a l u e s f o r seco n d p h i skew ness (W im b e rley , i n S te v e n s o n , 1961; W im berley, 1 9 6 4 ). A c c o rd in g t o W im berley ( i n S te v e n s o n , 1961) th e p re d o m i nance o f skewed s e d im e n ts s u g g e s t s m u l t i p l e o r i g i n s o f th e b o tto m m a t e r i a l s , o n ly one of w hich i s m a rin e d e p o s i t i o n o f d e t r i t u s from n e a r b y t e r r e s t r i a l r e g i o n s u n d e r p r e s e n t e n v i r o n m e n t a l c o n d i t i o n s . An abundance o f p o s i t i v e v a l u e s i n d i c a t e s t h a t s m a l l q u a n t i t i e s o f f i n e - g r a i n e d m a t e r i a l s a re b e i n g added t o an o t h e r w i s e n o rm a l s e d im e n t d i s t r i b u t i o n . T h is e x c e s s f i n e m a t e r i a l p r o b a b l y r e f l e c t s t h e a d ju s tm e n t o f th e s h e l f s e d im e n ts to p r e s e n t e n v i r o n m e n ta l c o n d i t i o n s , p a r t i c u l a r l y t h e c u r r e n t s e a l e v e l . The C h em ical P r o p e r t i e s o f S h e l f S e d im e n ts O rg a n ic m a t t e r i s a m inor c o n s t i t u e n t o f th e s e d i m ents on th e e n t i r e m a in la n d s h e l f . R apid c o n t r i b u t i o n o f i n o r g a n i c d e t r i t a l m a t e r i a l from th e c o n t i n e n t te n d s t o mask o r g a n i c m a t e r i a l p ro d u c e d i n t h e s e a and c o n t r i b u t e d t o th e s e d im e n t s . In r e g i o n s w here s e d im e n ts a r e c o a r s e g r a i n e d l a r g e p o r e s p a c e s betw een th e g r a i n s p r o v id e f o r good i n t e r s t i t i a l c i r c u l a t i o n , and c o n s e q u e n t l y o x i d a t i o n o f o r g a n i c d e b r i s can o c c u r below th e s e d im e n t- w a te r i n t e r f a c e . F u r t h e r , i n r e g i o n s n e a r s h o r e , on t o p o g r a p h i c 1 h ig h s in d e e p e r w a t e r , and i n a r e a s o f t o t a l n o n - d e p o s i t i o n , c u r r e n t a c t i o n r e t a r d s o r p r e v e n t s th e a c c u m u la tio n o f o r g a n ic m a t t e r . For t h e s e r e a s o n s o r g a n i c c o n t e n t i n c r e a s e s as g r a i n s i z e d e c r e a s e s (U c h u p i, i n S te v e n s o n , 1961; AHF:USC, 1 9 6 5 ). D a ta p r e s e n t e d by U chupi ( i n S te v e n s o n , 1961; T a b le 1; AHF:USC, 1965, T a b le 4 . 2 ) c l e a r l y s u p p o r t t h i s r e l a t i o n s h i p : s a n d , 0.017% N; s i l t y s a n d , 0.040%) N; sa n d y s i l t , 0.041% N; s i l t , 0.056% N; and c l a y e y s e d im e n ts , 0.091% N. The o n ly l a r g e a r e a w ith o r g a n i c c o n t e n t g r e a t e r t h a n 1 p e r c e n t i s t h e l a r g e mud d e p o s i t on t h e S a n ta B a r b a r a s h e l f . N i t r o g e n i s o f t e n u s e d a s an i n d e x o f t h e amount o f o r g a n i c m a t e r i a l p r e s e n t in t h e s e d im e n ts b e c a u s e t o t a l o r g a n ic m a t t e r i s d i f f i c u l t to d e te r m in e a c c u r a t e l y . T o t a l o r g a n i c m a t e r i a l i n t h e s e d im e n t can b e e s t i m a t e d by m u l t i p l y i n g th e p e r c e n t a g e n i t r o g e n by 17 (U c h u p i, i n S te v e n s o n , 1961; AHF:USC, 1 9 6 5 ). C a lc iu m c a r b o n a t e i s p r e s e n t i n a l l m a in la n d s h e l f s e d im e n t s , o f t e n a s b e n t h o n i c f o r a m i n i f e r a l t e s t s . O v e r a l l c a r b o n a te v a l u e s a r e low and r a r e l y e x c e e d 5 p e r c e n t . D i l u t i o n by d e t r i t a l i n o r g a n i c s e d im e n ts i s th e m a jo r f a c t o r i n m a i n t a i n i n g s e d im e n t c a r b o n a t e s a t low l e v e l s . I n many a r e a s t h e r e i s a g e n e r a l o f f s h o r e i n c r e a s e in c a lc iu m c a r b o n a te c o n t e n t as a r e s u l t o f d i m i n i s h e d d i l u t i o n o f c a l c a r e o u s m a t e r i a l by l a n d - d e r i v e d d e t r i t a l s e d im e n ts . The 443 h ig h c a r b o n a t e c o n t e n t o f s e d im e n ts on t h e P a l o s V e rd e s s h e l f o c c u r s b e c a u s e t h e s u p p ly o f d e t r i t a l m a t e r i a l u s u a l l y p r o v id e d by lo n g s h o r e d r i f t i s i n t e r r u p t e d by t h e i n t e r s e c t i o n o f Redondo su b m a rin e can y o n w i t h t h e s h e l f ( U c h u p i, i n S t e v e n s o n , 1961; AHF:USC, 1 9 6 5 ). A re a s o f s t r o n g c u r r e n t s and t u r b u l e n c e , su c h a s p o i n t s and h e a d l a n d s , f a v o r t h e a c c u m u l a t i o n o f a v e r y d i f f e r e n t ty p e o f c a l c a r e o u s m a t e r i a l , c o n c e n t r a t i o n s o f m o l- l u s c a n s h e l l s , b r y o z o a n s , c o r a l and f r a g m e n t s o f c a l c a r e o u s a l g a e . S u ch a r e a s o c c u r o f f P o i n t C o n c e p tio n , i n S a n ta M onica Bay, on th e P a l o s V e rd e s s h e l f , o f f P o i n t San M a te o , and o f f P o i n t Loma. S m a ll l i m e s t o n e r o c k f r a g m e n t s a r e a l s o an i m p o r t a n t s o u r c e o f c a r b o n a t e on t h e P a l o s V e rd e s s h e l f . C h e m ic a lly p r e c i p i t a t e d c a r b o n a t e p r o b a b l y i s a b s e n t from t h e s h e l f (U c h u p i, i n S t e v e n s o n , 1961; AHF:USC, 1 9 6 5 ). A D e t a i l e d A c c o u n t o f th e S e d im e n ts o f t h e S h e l f S u b d i v i s i o n s B o tto m s e d im e n ts o f t h e m a in la n d s h e l f v a r y c o n s i d e r a b l y a lo n g i t s l e n g t h . Some o f i t s a r e a s have r a t h e r c h a r a c t e r i s t i c s e d im e n t p a t t e r n s . The f o l l o w i n g d i s c u s s i o n , b a s e d on S t e v e n s o n , U ch u p i and G o r s l i n e (1 9 5 9 ) and W im berley ( i n S te v e n s o n , 1961; and 1964) and p r e v i o u s l y p a r t i a l l y i n c o r p o r a t e d i n J o n e s ( l a ] , i n S t e v e n s o n , 1 9 6 1 ) , p r e s e n t s a d e t a i l e d d e s c r i p t i o n o f th e n a t u r e o f th e 444 s u b s t r a t e and i t s d e s c r i p t i o n w i t h i n e a c h o f t h e e i g h t g e o g r a p h i c a r e a s o f th e s h e l f . The P o in t C o n c e p tio n S h e lf (A rea I ) The l o n g , n a rro w P o i n t C o n c e p tio n s h e l f h a s an e a s t - w e s t t r e n d p a r a l l e l i n g th e a d j a c e n t S a n ta Ynez moun t a i n s . The s h e l f i s 6 8 .8 km lo n g ( 3 7 .2 n a u t i c a l m i l e s ) and 3.3 km ( 1 .8 n a u t i c a l m i l e s ) to 8 . 1 km ( 4 . 4 n a u t i c a l m i l e s ) w id e. The maximum w id th i s a t S a n t a B a r b a r a P o i n t . The a re a o f the s h e l f i s 1 3 .7 p e r c e n t o f th e a r e a o f th e m a in land s h e l f ( B a r n a r d [ a ] , i n S te v e n s o n , 1961; C and GS C h a r t s 5101, 5 2 0 2 ) . A r e a I i s t h e d e e p e s t s h e l f r e g i o n ; more t h a n 50 p e r c e n t o f i t s a r e a i s d e e p e r t h a n th e 5 4 .8 m eter (30 fa th o m ) c o n t o u r , w h e re a s o n ly 30 p e r c e n t o f t h e a r e a o f the m a in la n d s h e l f l i e s b e lo w t h i s d e p t h (G. J o n e s , 1 9 6 4 ). The a r e a l d i s t r i b u t i o n o f se d im e n t t y p e s ( S t e v e n son, U chupi and G o r s l i n e , 1959) i s as f o l l o w s : r o c k , 8 .5 per c e n t ; o l i v e - g r e e n g r a v e l l y s a n d , 0 . 5 p er c e n t ; medium to f i n e o l i v e - g r e e n s a n d , 4 1 .2 p e r c e n t ; o l i v e - g r e e n s i l t y sa n d , 4 8 .2 p e r c e n t; and o l i v e - g r e e n san d y s i l t , 1 .6 p e r c e n t ( B a r n a r d , i n S te v e n s o n , 1 9 6 1 ). The s e d im e n t p a t t e r n i l l u s t r a t e d by S te v e n s o n , U chupi and G o r s l i n e ( 1 9 5 9 , F ig u r e 12) i s f a i r l y sim p le (A p p e n d ix F i g u r e C -7 ). Rock, g r a v e l and s h e l l d e b r i s a r e common along t h e s h o r e l i n e i n b o t h th e i n t e r t i d a l and s u b l i t t o r a l z o n e s . T here i s a l a r g e su b m arin e r o c k o u t c r o p a 445: few m i l e s e a s t o f P o i n t C o n c e p tio n t h a t i s 6 .5 km ( 3 .5 n a u t i c a l m i l e s ) i n l e n g t h and e x te n d s seaw ard f o r 3 .1 km ( 1 .7 n a u t i c a l m i l e s ) . Submerged r o c k a l s o o c c u r s a t th e o u t e r ed g e o f th e s h e l f o f f G o l e t a w here modern d e t r i t a l s e d im e n ts have f a i l e d t o c o v e r p o r t i o n s o f an e a s t - w e s t o r i e n t e d t r u n c a t e d a n t i c l i n e (W im b e rle y , i n S te v e n s o n , 1961; W im b erley , 1964; AHF:USC, 1 9 6 5 ). The u n c o n s o l i d a t e d s e d im e n ts a r e c o a r s e r on th e w e s te r n p a r t o f t h e s h e l f th a n t o th e e a s t . I n t h e v i c i n i t y o f P o i n t C o n c e p tio n , and im m e d ia te ly e a s t o f i t , th e c l a s t i c f r a g m e n t s , commonly o f g r a v e l s i z e , a r e th e c o a r s e s t on th e s h e l f . At th e edge o f th e s h e l f , 6 .8 km ( 3 .7 m i l e s ) e a s t o f P o i n t C o n c e p tio n , t h e r e i s a w e l l - d e f i n e d a r e a o f o l i v e - g r e e n g r a v e l l y s a n d . A t r e n d fro m c o a r s e t o f i n e s e d im e n ts w i t h i n c r e a s i n g d i s t a n c e from s h o r e i s l a c k in g h e r e . A c o n c e n t r a t i o n o f wave e n e r g y due t o r e f r a c t i o n around th e p o i n t p r e v e n t s d e p o s i t i o n o f f i n e d e t r i t a l ma t e r i a l s , th u s m a i n t a i n i n g t h e c o a r s e s u b s t r a t e i n t h e s e a r e a s ( S te v e n s o n , U chupi and G o r s l i n e , 1959, F ig u r e 12; W im berley, i n S te v e n s o n , 1961; W im b erle y , 1964; AHF:USC, 1 965). Along th e e n t i r e a r e a , a d e p o s i t o f medium t o f i n e o l i v e - g r e e n san d e x te n d s from th e s h o r e l i n e to v a r y in g d e p t h s . Betw een P o i n t C o n c e p tio n and G a v io ta t h e sand r e a c h e s a w a te r d e p th o f 91 m e t e r s . A s m a ll a r e a o f o l i v e - ; g re e n san d y s i l t l i e s a t th e edge o f t h e s h e l f o f f G o l e t a ■ 446' P o i n t . A l a r g e a r e a o f s t i c k y mud ( s i l t y s a n d , san d y s i l t and s i l t ) l i e s o f f C a p i t a n , C o al O i l P o i n t and G o l e t a P o i n t ( S te v e n s o n , U chupi and G o r s l i n e , 1959, F ig u r e 1 2 ) . Based on m ed ian d i a m e t e r s , s e d im e n ts on th e w e s t e r n t h i r d o f t h e P o i n t C o n c e p tio n s h e l f , b etw een t h e p o i n t and G a v io ta , a r e in t h e ra n g e o f f i n e t o v e r y f i n e s a n d s . Over m ost o f t h e r e m a in d e r of A re a I m edian d i a m e t e r s a r e c lo s e to t h e s a n d - s i l t b a r r i e r , 0 .0 6 2 mm. M edian d i a m e t e r s i n th e s i l t c a t e g o r y ( 0 .0 3 1 mm) o ccu r a t one p l a c e n e a r th e edge o f t h e s h e l f o f f C o al O i l P o i n t (W im b erley , i n S te v e n s o n , 1961; W im b erle y , 1964, F ig u r e 1 2 ) . S e d im e n ts a r e w e l l s o r t e d ( T r a s k c o e f f i c i e n t s , 1 . 0 0 - 2 . 5 0 ) over th e e n t i r e s h e l f e x c e p t f o r two l o c a l i t i e s on t h e e a s t e r n p a r t o f t h e s h e l f w here v a l u e s r i s e to th e m o d e r a t e l y s o r t e d c a t e g o r y ( 2 . 5 0 - 4 . 0 0 ) (W im berley, i n S te v e n s o n , 1961, F ig u re 1 6 ) . S tro n g p o s i t i v e sk e w n e ss p r e d o m in a te s , w i t h some w eak en in g o f t h i s p a t t e r n n e a r P o in t C o n c e p tio n (W im berley, i n S te v e n s o n , 1961, F i g u r e s 27, 32; W im b erle y , 1964, F i g u r e s 27, 3 4 ) . V a lu e s o f t o t a l n i t r o g e n a r e low (lo w o f 0 .0 0 9 p e r c e n t ) i n t h e c o a r s e s e d im e n ts n e a r P o i n t C o n c e p tio n and h ig h ( h i g h o f 0.122 p e r c e n t ) i n t h e f i n e r s e d im e n ts off- C o a l O i l , G o le ta and S a n ta B a r b a r a P o i n t s . The d i s t r i b u t i o n i s more no rm al (mean, 0 .0 5 1 p e r c e n t) o v e r th e r e m a in d e r o f t h e s h e l f w i t h v a l u e s g e n e r a l l y i n c r e a s i n g seaw ard (G. J o n e s [ c ] , i n S te v e n s o n , 1 9 6 1 ). The low v a lu e s from th e s e d im e n ts n e a r P o i n t C o n c e p tio n a r e p r o b a b l y th e r e s u l t of d i l u t i o n o f th e o r g a n i c m a t e r i a l by c l a s t i c s e d im e n t s , or th e y may i n d i c a t e t h a t t h e d e p o s i t i o n o f o r g a n i c m a t e r i a l i s re d u c e d by t u r b u l e n t w a t e r . The h ig h p e r c e n t a g e o f n i t r o g e n i n th e s e d im e n ts a t th e e a s t e r n end o f th e s h e l f i s r e l a t e d to f i n e - g r a i n e d m a t e r i a l and a g r e a t e r s t a n d i n g c ro p o f b e n t h i c o rg a n ism s ( S te v e n s o n , U chupi and G o r s l i n e , 1959; U ch u p i, i n S te v e n s o n , 1961; AHF:USC, 1 9 6 5 ). The p e r c e n ta g e o f c a lc iu m c a r b o n a t e i n t h e b o tto m d e p o s i t s i s h ig h o f f P o i n t C o n c e p tio n (maximum, 2 2 .4 p e r c e n t ) ; th e mean v a lu e f o r th e s h e l f i s 3 .4 p e r c e n t (G. J o n e s [ c ] , i n S te v e n s o n , 1961) and t h e minimum v a l u e , 0 . 9 p e r c e n t . The P o i n t C o n c e p tio n a r e a o f h ig h c a r b o n a t e c o n s i s t s p r i m a r i l y o f c o a r s e - g r a i n e d m o llu s c a n s h e l l f r a g m e n ts ( S te v e n s o n , U chupi and G o r s l i n e , 1959; U c h u p i, i n S t e v e n s o n , 1961; AHFrUSC, 1 9 6 5 ). M ajor o i l s e e p s a r e a b u n d a n t b e tw e e n P o i n t C on cep t i o n and G a v io ta . The s e d im e n ts n e a r o i l s e e p s a r e s t i f f and d a r k g re e n t o b l a c k i n c o l o r ( S te v e n s o n , U chupi and G o r s l i n e , 1 9 5 9 ). The S a n ta B a r b a r a S h e l f (A re a I I ) The m a in la n d s h e l f w id e n s e a s tw a r d from S a n ta B a rb a ra P o i n t . Over much o f i t s 4 7 .4 km ( 2 5 .6 n a u t i c a l m i l e s ) l e n g t h , from M o n te c ito to th e S a n t a C l a r a R i v e r , a distance of nearly 37.0 km (20 nautical miles), the shelf has a width of 13.0 km (7 nautical miles). It attains a maximum width of 17.6 km (9.5 nautical miles) in the vicin ity of Las Pitas Point. The shelf narrows abruptly at its eastern extreme, and the minimum width of 7.4 km (4.0 nau tical miles) is adjacent to the eastern wall of the Hueneme Submarine Canyon. The area of the shelf is 23.0 per cent of the total area of the southern California mainland shelf (Barnard [a], in Stevenson, 1961; C and GS Charts 5101; 5202). The western and eastern halves differ to the extent that they have been designated as two subdivisions, Area Ila and Area lib, divided at Las Pitas Point. When com pared on the basis of the percentage of the bottom area ly ing within each depth class, the western half (Area Ila) is the second deepest segment of the mainland shelf. This is in marked contrast to the eastern half, Area lib, which is the shallowest segment of the mainland shelf. If the 36.6 meter (20 fathoms) contour is selected, the following com parisons may be made: in Area Ila 66.5 per cent of the area lies below 36.6 meters, while in Area lib only 22.4 per cent lies below that depth. The area of the mainland shelf below 36.6 meters is 49 per cent. The distribution of bottom sediments, based on the percentage of the shelf covered by each type is as follows: rock, 2.5 per cent; imedium to fine olive-green sand, 10.2 per cent; olive-green 449 silty sand, 22.8 per cent; olive-green sandy silt, 30.5 per cent; and olive-green silt, 34.0 per cent (Barnard [a], in Stevenson, 1961; C and GS Charts 5101, 5202). Rock occurs in water shallower than 18.3 meters (10 fathoms) from Santa Barbara Point to Ventura and be tween the Santa Clara River mouth and Port Hueneme (Appen dix Figure C-7). It is conspicuously absent from the sub littoral region immediately north of the Santa Clara River (Stevenson, Uchupi and Gorsline, 1959, Figure 12). Rock is not an important substrate component of the Santa Barbara shelf. Three sedimentary units dominate the mainland shelf between Santa Barbara and Port Hueneme; Wimberley (in Stevenson, 1961; Wimberley, 1964; also see AHF:USC, 1965) has named these the Las Pitas Mud deposit, the Carpenteria Shelf-rise deposit and the Santa Clara Prodelta deposit. The dominant sedimentary feature of the western portion of the Santa Barbara Shelf (Area Ila), the Las Pitas Mud de posit, is an extensive area of ’’green mud” (silts and clayey silts) that covers 45 to 50 per cent of the area (Appendix Figure C-7) and extends for a distance of about 37.0 km (20 nautical miles, Santa Barbara Point to Las Pitas Point). It is widest (13.0 km or 7 miles) where the shelf is widest covering the bottom from 27.4 meters (15 fathoms) to 91.4 meters (50 fathoms). Sediments are the finest grained that occur anywhere on the mainland shelf 450 clay being more than 10 per cent. Median diameters range from 0.016 to 0.007 mm with the smallest median diameters on the shelf occurring at the center of the deposit. The sand content of the Las Pitas mud deposit is generally less than 1 per cent and consists almost entirely of organically derived particles. Skewness values are weakly positive. Probably the Las Pitas mud deposit represents the most dis tal fine-grained deposits from the Santa Clara and Ventura Rivers (Stevenson, Uchupi and Gorsline, 1959, Figure 12; Wimberley, in Stevenson, 1961; Wimberley, 1964; AHF:USC, 1965). A large isolated deposit of coarse sand, the Car penteria Shelf-Rise deposit, partly interrupts the Las Pitas mud deposit (Appendix Figure C-7). It is 16.6 km (9 miles) in length, 1.9 km (1 mile) wide, and rises about 6.1 meters (20 feet) above the general level of the sea floor. Its trend is oblique to the coastline. It disappears about. 1.9 km (1 mile) from shore, apparently as the result of the burial of its shoreward end. The ridge apparently acts as a dam, causing the deposition of fine clastic material that forms the western portion of the mud deposit. Wimberley (in Stevenson, 1961; Wimberley, 1964; AHF:USC, 1965) con siders the rise the surface expression of outcropping bed rock below the general surface of the shelf. Stevenson, Uchupi and Gorsline (1959) regard it as a beach ridge formed at a time of lowered sea level. The median diameters of its sediments range from medium to very fine sand; sorting is average to poor; skewness is weakly to strongly positive indicating movement of a small amount of fine material onto the rise (Wimberley, in Stevenson, 1961; Stevenson, Uchupi and Gorsline, 1959). Except for this offshore rise, sand occurs only on the shallow bottoms close to shore in Area Ila. East of Ventura, in Area lib, most of the shelf is covered by sand (Appendix Figure C-7). Contours of bottom topography bulge seaward in the vicinity of the mouths of the Sarxta Clara and the Ventura Rivers, between Las Pitas Point and Port Hueneme. Sediments decrease from coarse to fine from the river mouths toward the edge of the shelf. These facts suggest that sediments came from the river and thus consti tute a submarine prodelta deposit (the Santa Clara Prodelta Deposit: Wimberley, in Stevenson, 1961; Wimberley, 1964; AHF:USC, 1965). The sediments are well sorted near shore, of average sorting farther seaward, and become poorly sorted at the edge of the shelf. Skewness values indicate that a small surplus of fine material occurs throughout the region and that a greater surplus occurs on the seaward part of the deposit (Wimberley, in Stevenson, 1961; Wimber ley, 1964). A unique feature of this section of the shelf is the presence of high concentrations of woody debris in the sediments. This debris remained as an abundant residue following the screening of bottom samples. Three areas of this type of deposit apparently exist. Two of these lie almost due south of Las Pitas Point. The other is close to shore between the mouths of the Ventura and Santa Clara Rivers. The areal distribution of woody debris is mapped and contoured in Appendix Figure C-ll (Jones [c], in Stevenson, 1961, Figure 149; Uchupi, in Stevenson, 1961, Figure 57; Uchupi and G. Jones, Plate I, in press; and AHF:USC, 1965). The contour intervals are 0-2, 2-4, 4-8, 8-16, 16-32, and greater than 32 grams/liter (wet weight). Even a superficial examination leaves little doubt of the terrestrial origin of the woody debris. An example is pictured in Appendix Figure C-ll (Uchupi, in Stevenson, 1961, Plate I; Uchupi and G. Jones, Plate I, in press; AHFrUSC, 1965, Figure 4.14). The majority of the samples (73 per cent) examined contained a coarse debris fraction, with fragments greater than 4.699 millimeters (l/4 of an inch). The weight of this fraction varied between 0.2 and 569.7 grams with a mean of 54.4 grams. The coarsest frac tion was for the most part composed of sticks of varying sizes. The largest fragment (a stick) weighed 93.6 grams. Microscopic examination of the finer debris showed it to be composed of fragments of similar woody material. Both large and small particles in some samples appeared to : be charred (Appendix Figure C-ll). This blackened appear- | ance may be the result of changes following deposition or, j APPENDIX FIGURE C-ll Distribution of Woody Debris on the Shelf off Ventura. A. Bottom Sediments (from Stevenson, Uchupi and Gorsline, 1959). B. Woody debris, Sta. 5874, Lat 34°11.8r, Long. 119°25.7I, Depth, 75 Meters. C. Concentration of Woody Debris Expressed in Grams (Wet Weight) per Liter of Sedi ment. D. Concentration of Woody Debris Expressed in Grams (Wet Weight) per Square Meter of Bottom (Plate I, Uchupi and Jones, in press). 453 20' LA S P IT A S PT SAND /S h_t y ISAND /SANDY ISILT SILT 5K M f 100 S A N T A C L A R A R tV E R 3 4* VENTURA \ I . 0 S \ 7 7 ^ .A N G E L E S 122' 3 4 « GMS/L/reR tW E T WEIGHT) <2 <2 •N G M S / M (W E T W EIGHTt 454 455 more likely, may be the result of recent fires in the drainage basins of the Ventura and Santa Clara rivers. The fine fraction varied between 0.2 and 2096.8 grams with a mean of 298.0 grams/sample. The mean value of woody debris of all sizes was 343.0 grams (range from 3.9 to 2666.5) per sample (mean sample value, 39.2 liters) (G. Jones, in Stevenson, 1961; Uchupi, in Stevenson, 1961; Uchupi and G. Jones, in press; AHF:USC, 196 5). Nitrogen values increase east of Santa Barbara Point coincident with the Las Pitas mud deposit. The mean value for this region is 0.062 per cent (G. Jones [c], in Stevenson, 1961). A series of low values (about 0.03 per cent) marks the Carpenteria rise in Area Ila, with high values (above 0.10 to 0.12 per cent) in the muds on either side. Values are low in the prodelta region due to dilu tion by clastic sediments from the rivers. The percentages of calcium carbonate in the bottom deposits are low (mean, 3.1 per cent) over almost the entire area and have an ir regular pattern (G. Jones [c], in Stevenson, 1961). Marine carbonates, principally in the form of foraminiferal tests, are probably diluted by the deposition of clastic material from the Ventura and Santa Clara rivers (Stevenson, Uchupi and Gorsline, 1959; Uchupi, in Stevenson, 1961; AHFrUSC, 1965). The Mugu Shelf (Area III) The Mugu shelf is 22.2 km (12.0 nautical miles) in length and is one of the narrowest sections of the mainland shelf. The maximum width, 6.5 km (3.5 nautical miles), is just east of Hueneme Submarine Canyon, and the minimum, 0.9 km (0.5 miles) is at the head of Mugu Submarine Canyon. The shelf edge is irregular, and there are many small chan nels cutting across the shelf. The shelf off Mugu Lagoon, 12.4 km (6.7 miles) east of Port Hueneme, is crossed by the Mugu Submarine Canyon. The area of the Mugu shelf is only 5-1 per cent of the area of the mainland shelf. The per cent of bottom lying within each depth class of Area II is almost identical to that for the mainland shelf. The dis tribution of bottom sediment types, based on the percentage of bottom area covered by each type, is as follows: rock, 8.0 per cent; medium to fine olive-green sand, 30.0 per cent; olive-green silty sand, 62.0 per cent (Barnard [a], in Stevenson, 1961; C and GS Charts 5101, 5202; Stevenson, Uchupi and Gorsline, 1959, Figure 12). Rock occurs in the littoral zone and to the walls and heads of submarine canyons (Appendix Figure C-7). As 92 per cent of the bottom is covered by sands, the detrital materials on this shelf are by far the coarsest in the northern section of the mainland shelf. Median diameters are near the sand-silt limit; sediments range from well sorted near shore to poorly sorted at the shelf edge; 457 positive skewness predominates (Stevenson, Uchupi and Gorsline, 1959; Wimberley, in Stevenson, 1961; Wimberley, 1964). Much terrestrial plant debris is incorporated in the sediments and, like the woody debris in Area II, it probably originates from the Ventura and Santa Clara rivers. Organic nitrogen values are generally quite low (less than 0.05 per cent) over the entire Mugu shelf, but increase somewhat between Mugu Canyon and Point Dume at the edge of the shelf (greater than 0.05 per cent). The calcium car bonate content of the sediments is low (mean value, 3.4 per cent) over almost the entire area (G. Jones [c], in Steven son, 1961). The carbonate that does exist is principally in the form of foraminiferal tests (Stevenson, Uchupi and Gorsline, 1959). The Santa Monica Shelf (Area IV) Santa Monica Bay is a crescent shaped indentation in the coastline. The submarine physiographic provinces within the bay include: (1) the shelf, (2) Santa Monica and Redondo submarine canyons, (3) the basin slope, and (4) a portion of Santa Monica Basin. The shelf is one of the three best-known segments of the southern California main land shelf. Like the San Pedro Bay shelf and the San Diego shelf, it is characterized by a complex arrangement of sev eral bottom types. 458 I Along the northern portion of Santa Monica Bay the shelf has a rather constant width of from 4.6 km (2.5 miles) to 6.5 km (3.5 miles). The shelf and the coastline parallel the east-west trend of the Santa Monica Mountains. Off Santa Monica the coastline and the shelf gradually curve to the southeast. The shoreline is backed by the Los Angeles Coastal Plain. The shelf broadens and is about 11.1 km (6 nautical miles) wide at the head of Santa Monica Canyon. Between Santa Monica Canyon and Redondo Canyon, the "central shelf projection" extends 17.9 km (9.7 nauti cal miles) from shore and is about 6.7 km (3.6 miles) wide. The head of Redondo Canyon is within 0.9 km (0.5 miles) of the beach, and the shelf south of the canyon extends sea ward for a distance of 7.4 km (4.0 miles) off Palos Verdes Point. The overall length of the shelf, following around its curvature, is about 55.5 km (30 nautical miles) (C and GS Charts 5101, 5202). (The section of the shelf from the head of Redondo Canyon to Palos Verdes Point and adjacent to the northern face of the Palos Verdes Headland is in cluded within Area V, the Palos Verdes shelf.) The area of the Santa Monica Bay shelf is 12.8 per cent of the area of the mainland shelf. The distribution of the bottom within each depth class is essentially the same as that for the shelf as a whole. The distribution of the bottom sediment types, based on the percentages of the area covered by each type, is as follows: rock, 6.9 459 per cent; olive-green sandy gravel, less than 0.1 per cent; coarse red sand, less than 0.1 per cent; medium to fine olive-green sandy silt, 25.9 per cent; and olive-green silt, 1.9 per cent (Barnard [a], in Stevenson, 1961; Stevenson, Uchupi and Gorsline, 1959, Figure 17). A continuous band of medium to fine olive-green sand extends from Point Dume to Redondo Canyon and beyond (Appendix Figure C-8). This band is narrow along the northern portion of the shelf, but gradually widens until it extends seaward more than two miles between El Segundo and Redondo Beach. Between Ballona Creek and El Segundo patches of coarse red sand lie within the boundaries of the olive-green sand. Off El Segundo sands are blackened and hydrogen sulfide is present as a result of the discharge from the Los Angeles City Sewer Outfall (Hyperion). Sea ward of the sand belt is a continuous but highly irregular deposit of olive-green silty sand. Within this silty sand area off Santa Monica are two large patches of coarse sand (Stevenson, Uchupi and Gorsline, 1959, Figure 17). Fine sediments, sandy silt, and silt occur in small patches on the northern shelf, at the outer edge of the central shelf projection, and shoreward and south of the large area of rock on the central shelf projection (Appen dix Figure C-8). Coarse materials on the shelf include rock outcrops (siliceous shales, mudstones, and sandstones) and transported rocks (pebbles and cobbles of igneous, 460 metamorphic and sedimentary types). The authigenic miner als, phosphorite and glauconite, are common in Santa Monica Bay. Phosphorite is abundant with rock and gravel on the central shelf projection, and glauconite is present at the outer edge of the northern shelf, in the sediments around the rock and gravel on the central shelf projection, and at the head of Santa Monica Canyon (Stevenson, Uchupi and Gorsline, 1959, Figure 17). Median diameters in the northern part of the bay show a seaward progression from very fine sands to coarse silts. South of the mouth of Ballona Creek median diameter contours curve slightly seaward. Coarse silt separates the nearshore sands from those of the central shelf projection (Wimberley, in Stevenson, 1961; Wimberley, 1964; AHF:USC, 1965). According to Wimberley (1964, p. 102), "most sedi ments on the central plateau are very fine sands (medians 0.062 mm to 0.125 mm), but some samples are as coarse as 0.60 mm." Except for the poorly sorted coarse sediments of the central shelf projection, sediments in Santa Monica Bay are well sorted. First phi skewness values are negative for sediments of the central shelf projection, indicating an abundance of coarse material, rock and shell fragments. Elsewhere values are weakly positive, indicating a slight excess of fine sediments. Nearly all sediments on the Santa Monica Bay shelf have positive second phi skewness 461 values; indicating that all of the regions are receiving at least a small excess of fine sediments (Wimberley, in Stevenson, 1961; Wimberley, 1964). Nitrogen values in Area IV are somewhat higher than elsewhere on the shelf due to the substantial contribution of organic material from waste discharge operations. The mean value for the area is 0.050 per cent (G. Jones Ic], in Stevenson, 1961). The calcium carbonate content in the sediments is high over most of the central shelf projection and is in the form of shell fragments. Values at most sampling locations exceed 10 per cent (high for the central shelf projection, 16.8 per cent) (Uchupi, in Stevenson, 1961; AHF:USC, 1965). The Palos Verdes Shelf (Area V) The Palos Verdes shelf is the smallest segment of the mainland shelf, comprising only 2.4 per cent of the total area. It is 25.5 km (13.8 miles) in length and has a maximum width of 8.3 km (4.5 miles) and a minimum width of 1.9 km (1.0 miles). This is the narrowest portion of the mainland shelf. The percentage of bottom area lying within each depth class for Area V is similar to that for the en tire mainland shelf (C and GS Charts 5101, 5202). The distribution of bottom sediment types, based on the percentage of area covered by each, is as follows: rock, 11.7 per cent; medium to fine olive-green sand, 6.2 per cent; coarse red sand, 22.4 per cent; olive-green silty sand, 38.3 per cent; and olive-green sandy silt, 21.5 per cent (Barnard [a], in Stevenson, 1961). About 5 per cent (ca. 1.7 km2 or 1 square mile) of the bottom sediments are blackened as a result of waste discharge operations (Appen dix Figure C-8) (Los Angeles County Sewer Outfall at White’s Point). Here sediments contain a high percentage of terrestrial plant fragments, and hydrogen sulfide is strongly evident. Much of the littoral zone is made up of rocky platforms and rocky or gravelly beaches. Below the littoral zone the rock is covered by a thin layer of gravel and shell debris. At greater depths finer sediments, olive-green sands and silty sands, cover the shelf (Steven son, Uchupi and Gorsline, 1959, Figure.17). The concentration of organic nitrogen in the sedi ments in the vicinity of the Los Angeles County Sewer Out fall (White’s Point) results in values higher than normally expected on the shelf. The maximum values exceed 0.150 per cent, compared with a shelf mean of 0.079 per cent (G. Jones [c], in Stevenson, 1961). The mean itself is high. These high values are a reflection of the substantial quan tities of organic material contributed to the sea in waste discharge operations. The sediments of this region are also high in calcium carbonate. Areas of high concentra tions are at Palos Verdes Point (maximum, 63.5 per cent) and Point Fermin. The high calcium carbonate values result 463: from a substantial decrease in dilution by inorganic clas- ; tic detrital sediments. Redondo Canyon to the north and the San Pedro Sea Valley to the south, acting as sediment traps, greatly reduce the contribution of material that might otherwise be supplied to the area by longshore drift (Stevenson, Uchupi and Gorsline, 1959; Uchupi, in Steven son, 1961). The San Pedro Shelf (Area VI) San Pedro Bay is a shallow, curved indentation of the southern Californian coastline east of Palos Verdes headland. It is 35.2 km (19.0 nautical miles) long, has a maximum width of 21.1 km (11.4 nautical miles) at the cen ter, and a minimum width of 2.4 km (1.3 miles) at the east ern limit of the area, Newport Submarine Canyon. The shelf area is 13.4 per cent of the total area of the mainland shelf. The distribution of bottom area by depth classes is similar to that in Area lib, as the San Pedro Bay shelf is the second shallowest segment of the mainland shelf (C and GS Charts 5101, 5202). The distribution of bottom sediment types, based on the percentage of the area covered by each, is as follows: rock, 1.9 per cent; light olive-green gravelly sand, less than 0.1 per cent; medium to fine olive-green sand, 63.0 per cent; coarse red sand, 9.6 per cent; olive-green silty sand, 15.7 per cent; olive-green sandy silt, less than 0.1 per cent; dark gray sandy silt, 8.3 per cent; and black sandy silt, 1.2 per cent (Barnard [a], in Stevenson, 1961). The distribution of these substrate types is complex (Ap pendix Figure C-8). Rock occurs along the Palos Verdes headland, near Point Fermin, in a large area two to four nautical miles seaward of the Los Angeles Harbor entrance, along the walls of the submarine canyons, and at the outer edge of the shelf. Rock in place includes medium gray sandstones, porcellanous shales, dark olive-green lime stones, and friable sandstones. Transported rock and gravel occur mostly along the margins of the large offshore outcrop where they are associated with coarse red sand. These rocks are predominantly yellowish-brown limestone. Well-indurated sandstone, siliceous shale, and a few peb bles of granite, quartz, hard mudstone, and phosphorite also occur. Red sand also lies in a large patch off Sunset Beach (Stevenson, Uchupi and Gorsline, 1959, Figure 17). Most of the shelf outside the harbor is covered by medium to fine olive-green sand (Appendix Figure C-8). Olive-green sandy silt is located only at the outer edge of the shelf. Black sandy silt occurs off the bottoms at the west end (closed end) of the Los Angeles Outer Harbor. The color is the result of reducing conditions caused by waste discharge operations and poor general water circulation. Hydrogen sulfide was evident in samples from this area. The bottoms in the remainder of the outer harbor area are 465 of dark gray sandy silt (Stevenson, Uchupi and Gorsline, 1959). Most of the sediments of the San Pedro shelf have medium diameters in the very fine sand category, with an area of coarse silt off Huntington Beach and fine sand off Alamitos Bay. Sediments on the shoreward part of the shelf have average sorting, seaward they are well sorted, and the fine-grained deposits behind the breakwater are poorly sorted. Phi skewness values are negative for sediments in the central part of the area near the rock outcrops. Val ues indicate an excess of coarse debris such as would be contributed by eroding rock. An elongate area of negative values extends southeastward toward Newport Beach indicat ing the transport of coarse material in that direction. Skewness is weakly positive on the rest of the shelf except off Huntington Beach, where beach sands provide a source of coarse material (Wimberley, in Stevenson, 1961; Wimberley, 1964). Organic nitrogen values are uniformly low (mean of 0.033 per cent) on most of the shelf. Slow contributions to the sediments, rather than dilution by elastics, seem to account for the low values. The Los Angeles Breakwater, acting as a dam or sediment trap, causes the deposition in the outer harbor of much of the organic material resulting from human activities (Stevenson, Uchupi and Gorsline, 1959; Uchupi, in Stevenson, 1961). The organic content of 466 : harbor bottom sediments measured by Reish (1959c) is much higher (maximum of 4.7 per cent) than the values for the rest of the shelf. Calcium carbonate values are high on the outer edge of the shelf, at the head of San Pedro Sea Valley (6.9 per cent), and at a few stations near the mouth of the Santa Ana River (8.9 per cent). The mean value for all samples analyzed from this area is 2.6 per cent (Stevenson, Uchupi and Gorsline, 1959; G. Jones [c], in Stevenson, 1961; Uchupi, in Stevenson, 1961; AHFrUSC, 1965). The Newport-La Jolla Shelf (Area VII) The shelf between Newport Canyon and La Jolla Canyon is long and narrow. Its length is 104.0 km (56.2 nautical miles), and the maximum width is 9.8 km (5.3 miles). It narrows to 1.7 km (0.9 miles) off Balboa, 2.0 km (1.1 miles) off Dana Point, 1.9 km (1.0 mile) at Carlsbad Canyon, and 1.9 km (1.0 mile) at La Jolla Canyon. The area of this segment of the shelf is 15.3 per cent of the area of the mainland shelf. The percentage of bottom lying within each depth class is similar to that for the entire mainland shelf (C and GS Charts 5101, 5202). The distribution of bottom sediment types, based on the percentages of area covered by each, is as follows: rock, 2.0 per cent; medium to fine olive-green sand, 12.5 per cent; olive-green silty sand, 41.3 per cent; olive-green 467 : sandy silt, 43.2 per cent; olive-green silt, 1.0 per cent (Barnard [a], in Stevenson, 1961). Rock is common in depths of less than 18.3 meters (60 feet) from Corona del Mar to San Mateo Point, in the vicinity of Carlsbad, and south of Del Mar (Appendix Figure C-9). Sand is restricted to a narrow continuous belt close to shore. Silty sands and sandy silts dominate the majority of the shelf. A con tinuous but irregularly shaped area of silty sand extends the entire length of this region, seaward of the belt of medium to fine olive-green sand. Farther offshore sandy silts predominate, but south of Encinitas sandy silts are nearly absent. Silt is absent from this portion of the shelf except for two small patches, one near Laguna and one off Carlsbad. Mica is conspicuous in the sediments from the Santa Margarita River to Carlsbad (Stevenson, Uchupi and Gorsline, 1959, Figure 20). The sediment median diameters close to shore are those of very fine sands. On the rest of the shelf, as far south as Carlsbad, coarse silts (median diameters rarely less than 0.040 mm) predominate. South of Carlsbad sedi ments are coarser sands and some silty sands, with median diameters in the very fine sand range (0.062-0.125 mm) from shore to the edge of the shelf. North of Carlsbad sedi ments are well sorted near shore and of average sorting in deeper water. Skewness values indicate that a surplus of fine material is being deposited over the entire region. 468 South of Carlsbad, most sediments are moderately sorted (0.50-1.00); skewness values lack a particular geographic pattern (Wimberley, in Stevenson, 1961; Wimberley, 1964). Nitrogen values increase offshore (from less than 0.05 per cent to greater the 0.05 per cent) as the sediment median diameters decrease; the mean value for this shelf is 0.047 per cent (G. Jones [c], in Stevenson, 1961). Sediments of this region are low (mean value, 2.3 per cent) (G. Jones [c], in Stevenson, 1961) in calcium carbonate except in a small area off San Mateo point (high value of 7.1 per cent here) (Uchupi, in Stevenson, 1961; AHF:USC, 1965). The San Diego Shelf (Area VIII) The San Diego Shelf is 38.3 km (20.7 nautical miles) in length and has been arbitrarily divided at Point Loma into two segments (Areas Villa and VUIb). North of the Point the shelf is relatively narrow. The minimum width is at La Jolla Canyon (0.9 km or 0.5 mile), and the maximum off Mission Bay (10.0 km or 5.4 miles). The sedi ments of this part of the shelf (Area Villa) are similar to those of Area VII. South of Point Loma the shelf widens to 16.3 km (8.8 nautical miles) off Imperial Beach. The sedi ments of this area differ significantly from those to the north. The shelf area (Villa and VUIb) is 14.3 per cent of the total area of the mainland shelf. The percentage of bottom area lying within each of the depth classes in both 469 subdivisions of Area VIII parallels that for the whole mainland shelf (C and GS Charts 5101, 5202). The distribution of bottom sediment types on the San Diego shelf, based on the percentage of area covered by each type, is as follows: rock, 8.8 per cent; medium to fine olive-green sand, 37.3 per cent; coarse gray sand, 10.2 per cent; coarse red sand, 11.5 per cent; olive-green silty sand, 17.4 per cent; and olive-green sandy silt, 14.6 per cent (Barnard [a], in Stevenson, 1961). Rocks in place extend offshore from Point La Jolla to Mission Bay and from Mission Bay to Point Loma, and project southward from Point Loma (Appendix Figure C-9). The maximum width of the rocky zone is nearly 3.7 km (2 miles), and submerged outcrops ex tend southward from Point Loma for about 7.4 km (4 miles). At this point an area of gravel separates the rock from an isolated outcrop lying 9.3 to 11.1 km (5 to 6 miles) south of Point Loma and about the same distance off Imperial Beach. Another large area of submerged rock surrounds the Los Coronados Islands and extends southward along the edge of the shelf (Stevenson, Uchupi and Gorsline, 1959). Gravel and transported rock occur mainly in the vicinity of rocky outcrops (Appendix Figure C-9). Addi tional areas of gravel have been reported from bottoms off the mouth of the Tijuana River and the entrance to San Diego Bay (Stevenson, Uchupi and Gorsline, 1959, Figure 20) . Fine olive-green sand is the most common sediment type on the San Diego Shelf. It extends from Point La Jolla to south of the Mexican border, and grades into silty sand and sandy silt at the edge of the shelf. A large area of medium to coarse gray sands occurs off Imperial Beach and the mouth of the Tijuana River and extends beyond the Mexican border. The major area of medium to coarse red sand is located seaward of the gray sand area off the Tijuana River and the isolated offshore rocky outcrop. Two smaller patches of red sand occur south of Point Loma. Three red sand areas are located within the gray sand off the Mexican border (Stevenson, Uchupi and Gorsline, 1959, Figure 20). According to Wimberley (in Stevenson, 1961; Wimber ley, 1964; AHF:USC, 1965) both of two markedly different kinds of sediment, a fine gray sand (= olive-green sand of Stevenson, Uchupi and Gorsline, 1959) were not deposited under the present environmental conditions. The gray sand is well sorted; the brown sand has median diameters of 0.250 mm, a sand content of 98 per cent, and is partly well sorted and partly of only average sorting. Skewness values in both deposits are generally negative. He concludes that the gray sands were left behind after the end of the Pleistocene Epoch. He considers the red sand a deposit laid down when the sea level was about 91 meters lower and the shelf exposed to subaerial processes. The deposits were reworked and redistributed by the advancing sea as sea level rose. In the sediments of the northern portion of the San Diego dhelf, organic nitrogen values are low nearshore (less than 0.05 per cent). Higher values (greater than 0.05 per cent) are from the areas of finer sediment at the outer margin of the shelf. Organic nitrogen values are also low (minimum of 0.001 per cent) in the southern por tion of the San Diego dhelf. The calcium carbonate content of the sediments is high off Point La Jolla (13.7 per cent), the Point Loma Peninsula (11.9 per cent), and seaward of the isolated offshore rocky area (12.2 per cent) (Steven son, Uchupi and Gorsline, 1959; Uchupi, in Stevenson, 1961; AHFtUSC, 1965). The Nearshore Sediments Sediment samples from the shallow water depths along the entire shore are more closely related to each other than to samples from the adjacent but deeper parts of the mainland shelf. The nearshore environment may be con sidered a separate sedimentary unit. Its characteristics are relatively constant along the full length of the main land shelf. The nearshore facies is transitional between the intertidal and the deeper water sediments and shows marked changes in sediment characteristics within a short seaward direction (Wimberley, in Stevenson, 1961; Wimberley, 1964; AHF:USC, 1965). The nearshore transects, in general, show a de crease in grain size seaward to 4.7 meters. Farther from shore, the decrease in grain size with distance from shore is less distinct. Variations in this trend result from shell material or nearby sources of coarse clastic parti cles. Size characteristics of samples from the same depth of water are not comparable from transect to transect be cause of local environmental and of different source fac tors (Wimberley, in Stevenson, 1961; Wimberley, 1964; AHFrUSC, 1965). Samples from the nearshore environment are brown or gray in color, in contrast to the olive-green sediments of most of the outer shelf. They are well sorted and general ly have negative skewness values, indicating a surplus of coarse particles in contrast to the positive values of most of the mainland shelf. These characteristics of the near shore environment results from the vigorous sediment trans port by waves breaking along the beaches (Wimberley, in Stevenson, 1961; Wimberley, 1964). The Water over the Southern California Borderland and the Mainland Shelf The complexity of the southern Californian sea ap proaches that of the ocean floor beneath it. The dominant hydrographic feature here, as elsewhere along the California 473 : coast, is the California Current. It controls the general water character and circulation of the region. The Cali fornia Current is a part of the great clockwise circulation of the North Pacific. It flows southeastward as an exten sion of the Japanese and Aleutian Currents. The water that it brings south is generally colder and less salty than that farther offshore (Reid, Roden and Wyllie, 1958; Stev enson, in Stevenson, 1961, and in AHFrUSC, 1965; Stevenson, 1963). As a result of the indentation of the southern California coast, the current flows past the borderland at its seaward edge, about 300 km offshore. Over the border land, east of the current, a large permanent eddy, the Southern California Countercurrent, is centered over the Santa Rosa-Cortez Ridge (Appendix Figure C-12). Water mov ing in this eddy remains off southern California for 10 to 20 days. The land mass protects the waters on the eastward side of the eddy from the northwest winds, and the eddy it self partially separates these inshore waters from the colder offshore current. The current eventually turns southward and follows the coast east of the eddy and over the shelf (Emery, 1960; Reid, Roden and Wyllie, 1958; Stevenson, in Stevenson, 1961 and in AHF:USC, 1965; Steven son, 1962; 1963). Numerous smaller eddies also form over the border land. According to Schwartzlose (1963) "the southern APPENDIX FIGURE C-12 Surface Currents of the Southern California Sea Expressed Diagrammatically (After Figure 25, Stevenson [a], in Stevenson, 1961). 474 M 0 J A V E C T Q san ® *b " I e lV — SANTA MONICA <M3UHTAMS '-• SOO' — SAN MIGUEL*' ISLAND SANTA CRUZ ISLAND I santa R o s f.Island SANTA BARBARA ISLAND SANTA CATAUKA ISLAND SAN NICHOLAS ISLAND - v LA SOUTHERN CALIFORNIA COASTAL AREA PftMCPAL 1 STtWT STATUTE MILES 476 California circulation is different from the rest of the coast in that eddies predominate.” Drift bottle returns indicate eddies between Santa Rosa-Santa Cruz Islands, and San Nicolas-Santa Catalina Islands, between San Clemente Island and the mainland, and another between Santa Catalina and the mainland. Below 200 meters a deep countercurrent, flowing northward along the coast from Baja California to Cape Mendocino, brings warmer and more saline water, ’’Southern Water,” to the higher latitudes. In the late fall and early winter a surface manifestation of this current, the Davidson Current, develops. There is little evidence of this surface counter-current south of Point Conception (Emery, 1960; Schwartzlose, 1963; Reid, Roden and Wyllie, 1958). The water masses of the borderland have their prin cipal origin in the North Pacific Ocean; ’’ Northern Water” is delivered to the borderland by the California Current. This water is considerably modified when eddy circulation and upwelling mix it with deeper water of southern origin (Emery, 1960; AHF:USC, 1965). Four different submasses of Northern Water have been recognized above 300 meters over the borderland; these are (1) the offshore surface water of the California Current, (2) upwelled surface water mainly over the Santa Rosa-Cortez Ridge, (3) southern California countercurrent surface water, an admixture of the first two,, 477 and ( 4 ) m a in la n d s h e l f w a t e r . The w a te r o v e r t h e m a in la n d s h e l f , g e n e r a l l y s p e a k i n g , r e p r e s e n t s a p ro n o u n c e d m o d i f i c a t i o n o f th e w a t e r inco m in g t o t h e b o r d e r l a n d . W ater t e m p e r a t u r e s a r e h i g h b e c a u s e o f h e a t i n g d u r in g ed d y c i r c u l a t i o n ; s u r f a c e l a y e r s a r e e i t h e r s a t u r a t e d o r s u p e r s a t u r a t e d w i t h o x y g e n ; th e c o n c e n t r a t i o n s o f n u t r i e n t s a r e more v a r i a b l e t h a n t h o s e o f f s h o r e . The e n t i r e m a in la n d s h e l f w a t e r su b m a s s , from P o i n t C o n c e p tio n t o th e M exican b o r d e r , i s u n i f o r m i n i t s g r o s s a s p e c t s . I t r e a c t s a s a u n i t t o a n n u a l and o t h e r p e r i o d i c v a r i a t i o n s , b u t c e r t a i n n o n - p e r i o d i c d i f f e r e n c e s o c c u r i n s p e c i f i c l o c a t i o n s . The uneven s h o r e l i n e and com plex su b m a rin e to p o g r a p h y r e s u l t i n d i s t i n c t l o c a l w a t e r c o n d i t i o n s o v e r some s e g m e n ts o f t h e s h e l f ( S t e v e n s o n , i n S t e v e n s o n , 1 9 6 1 , and i n AHFrUSC, 1965; S t e v e n s o n , 1962; 1 9 6 3 ). W ater M o tio n W ater m o tio n o v er t h e s h e l f i s p r e d o m i n a n t l y t h e r e s u l t o f w ind a c t i o n . S e c o n d a ry c u r r e n t s a r e fo rm e d from v a r i a t i o n s i n t h e d e n s i t y d i s t r i b u t i o n c a u s e d by t h e w in d . I n s m a l l a r e a s , n e a r can y o n h e a d s , s e c o n d a r y e f f e c t s o f t h e t i d e may d e v e lo p l o c a l and m in o r c u r r e n t s . The b a s i c w a t e r movement o v e r t h e s h e l f i s to t h e s o u t h e a s t and a lo n g th e c o a s t . . . . From G o l e t a to S a n t a B a r b a r a , a w e s t e r l y f lo w in g c u r r e n t i s c h a r a c t e r i s t i c and a s i m i l a r n e a r s h o r e n o r t h w e s t e r l y f lo w o c c u r s o v e r th e O cean s i d e S h e l f . S t r o n g e s t c u r r e n t s f lo w s o u t h e a s t e r l y w i t h th e w i n d s , and th o s e o f f P o i n t M ugu, P a lo s V e rd e s H i l l s , and P o i n t Loma a t t a i n t h e g r e a t e s t v e l o c i t i e s ( a b o u t 0 .6 k n o t ; h i g h e r when accom panied by w in d s w i t h v e l o c i t i e s g r e a t e r t h a n 25 k n o t s ) . Waves o v e r t h e s h e l f a r e m a in ly o f l o c a l o r i g i n and t h u s a r e low and have p e r i o d s o f 5 -9 s e c o n d s . M ost o f th e c o a s t i s p r o t e c t e d by t h e o f f s h o r e 478 i s l a n d s . . . fro m s w e l l o r i g i n a t i n g i n th e open se a . T hese e x o t i c w aves do, how ever, a p p ro a c h from a w e s t e r l y d i r e c t i o n a lo n g th e Y e n tu ra -O x n a rd c o a s t , in S a n t a M onica Bay and a t San D ieg o . Long s o u t h e r ly s w e l l i s common i n th e summer and s t r i k e s th e sh o re m ost e f f e c t i v e l y s o u th o f P a lo s V erd es H i l l s . S w ell i s more p r e v a l e n t i n th e w i n t e r and t u r b u l e n t m ix in g i n t h a t s e a s o n e x t e n d s to g r e a t e r d e p t h s th a n i n t h e warmer m o n th s. The a n n u a l v a r i a t i o n i n th e th e r m o c lin e f o l l o w s t h i s t r e n d , w i t h d e p t h s v a r y in g from 10-50 f e e t i n t h e summer and 50-150 f e e t i n th e w i n t e r . The s h e l f w a t e r s w i t h th e l e a s t wave a c t i o n , and th u s m ix in g , a r e i n t h e S a n ta B a r b a r a and V e n tu ra em baym ents, and e a s t o f th e P a l o s V e rd e s H i l l s and th e P o i n t Loma H e a d la n d . A l l o t h e r c o a s t a l s e c t i o n s have w av es, m a in ly o f l o c a l o r i g i n , a p p r o a c h in g th e sh o re n e a r l y e v e r y d a y . R o u g h e st w a t e r s a r e o f f P o in t Mugu, w e s t o f th e P a lo s V e rd e s H i l l s , and o v e r - th e O c e a n s id e S h e l f . ( S te v e n s o n , 1962, p. 456) T r a n s p a r e n c y The amount o f l i g h t p r e s e n t a t d i f f e r e n t l e v e l s i n th e se a i s an i m p o r t a n t v a r i a b l e c o n t r o l l i n g p rim a ry p r o d u c t i v i t y . L ig h t may a l s o be an i m p o r t a n t f a c t o r i n d e t e r m in in g t h e ab u n d a n c e , ty p e and d i s t r i b u t i o n o f c e r t a i n t y p e s of b e n t h i c a n im a l s p e c i e s , and may c o n s e q u e n t l y , u n d e r c e r t a i n c o n d i t i o n s , a l t e r community s t r u c t u r e . Reduced t r a n s p a r e n c y s e r v e s a s an i n d i r e c t m easu re o f th e amount o f s u sp e n d e d m a t e r i a l i n th e w a te r colum n. The mean v i s u a l t r a n s p a r e n c y i n th e w a t e r s o v e r t h e s h e l f f o r a l l s e a s o n s th r o u g h o u t t h e p e r i o d o f th e AHF S u rv ey v a r i e d from l e s s t h a n 6 to more th a n 15 m e t e r s , w ith v a l u e s i n c r e a s i n g i n a seaw ard d i r e c t i o n (A p p en d ix F ig u r e C -1 3 ). R e g io n a l d i f f e r e n c e s a re a p p a r e n t . A band o f low APPENDIX FIGURE C-13 Y e a r l y Mean V i s u a l T r a n s p a r e n c y o f S o u th e r n C a l i f o r n i a n C o a s t a l W aters as M easured by th e S e c c h i D is c ( F i g u r e 40, T ib b y , i n S t e v e n s o n , 1961; and i n F i g u r e 3 . 2 7 , AHF:USC, 1 9 6 5 ). 479 480 F ig u re C-13 J » 2 * ___________ «____________k t lju m n a 0C*Crt I* P C W N T YEA RLY M E A N VISUAL TRANSPARENCY IN F E E T SECCHI DISC 1 FOOT = 0.3048 METERS t r a n s p a r e n c y w a te r o c c u r s g e n e r a l l y a lo n g th e c o a s t a b o u t a m ile or so o f th e b e a c h . T r a n s p a r e n c i e s a r e l e s s th a n 6 m e te r s o f f a l l u v i a l la n d p l a i n s , and a r e b e tw e e n 6 and 12 m e te r s o f f ro c k y s h o r e s . O cean ic w a te r i n t r u d e s over th e s h e l f , o f t e n e x te n d in g w i t h i n a m ile o f th e s h o r e . Even o ver th e b r o a d S a n ta B a r b a r a and San Diego s h e l v e s , to n g u e s o f o f f s h o r e w a te r p r o j e c t c o n s i d e r a b l e d i s t a n c e s to w ard s h o r e . Such c l e a r w a te r d o e s n o t o c c u r over t h e S a n ta M onica and San P e d ro s h e l v e s . M o d e r a te ly t u r b i d w a te r (6 to 12 m e t e r s ) i s common 2 2 .2 t o 2 7 .8 km from s h o re i n t h e s e r e g i o n s o f f c o a s t a l a r e a s o f h ig h human d e n s i t y . I n th e s p r i n g , t r a n s p a r e n c i e s a r e low er and e x t i n c t i o n c o e f f i c i e n t s h i g h e r i n th e v i c i n i t y o f a l l u v i a l la n d p l a i n s o f t h e V e n tu r a and Los A n g e le s B a s in s . T h is i s r e l a t e d to th e i n c r e a s e d r u n o f f fro m th e la n d d u r in g t h i s s e a s o n . M an’ s a c t i v i t i e s a r e r e f l e c t e d i n re d u c e d t r a n s p a r e n c i e s i n some a r e a s , b u t have n o t p ro d u c e d a r e a s o f e x c e p t i o n a l l y low t r a n s p a r e n c i e s . L o c al e f f e c t s o f w a s te d i s ch arg e can be o b s e r v e d , b u t as y e t do n o t a p p e a r to be o f s u f f i c i e n t m ag n itu d e to change th e g e n e r a l p a t t e r n o f t r a n s p a r e n c y d i s t r i b u t i o n ( T ib b y , i n S te v e n s o n , 1961; and i n AHF:USC, 1965; S te v e n s o n and P o l s k i , 1 9 6 1 ). T e m p e ra tu re W ater t e m p e r a t u r e s a r e h i g h l y v a r i a b l e over th e s h e l f . B ec au se t e m p e r a t u r e v a r i e s w ith l o c a t i o n , w ith 482 d e p th i n th e w a te r colum n, and w i t h tim e , i t i s e x c e e d i n g l y d i f f i c u l t t o d e s c r i b e t h i s v a r i a b l e a d e q u a t e l y by any sim p l e g e n e r a l i z a t i o n . The number o f o b s e r v a t i o n s made d u r in g t h e A lla n H ancock F o u n d a tio n s u r v e y a re s u f f i c i e n t t o c h a r a c t e r i z e g e n e r a l l y t h i s e n v i r o n m e n ta l p a r a m e t e r , b u t a re n o t s u f f i c i e n t to d e t a i l i t s l o c a l v a r i a t i o n s . The mean v a l u e s p r e s e n t e d f o r t h e s h e l f a r e a s a re p a r t l y b a s e d on th e sum m ation o f s t a t i o n v a lu e s d i s t r i b u t e d i n tim e (T a b le 3 . 1 ; AHF:USC, 1 9 6 5 ). T e m p e ra tu re s i n c r e a s e to w a rd th e s o u th i n t h e w a te r o v er th e s h e l f (A p p en d ix F ig u re C - 1 4 ) . T h ro u g h o u t th e y e a r , the w arm est s h e l f w a te r s a r e along t h e c o a s t from Dana P o i n t to La J o l l a . The c o o l e s t t e m p e r a t u r e s o b s e rv e d o c c u r re d i n a r e a s o f u p w e llin g a t P o i n t C o n c e p tio n , P o in t Mugu, P o i n t Ferm in and P o i n t Loma. I n th e f i r s t q u a r t e r o f t h e y e a r (A p p en d ix F ig u re C - 1 4 ) , th e s e a so n o f g r e a t e s t c o o l i n g and w ind m ix in g tem p e r a t u r e s alo n g th e e n t i r e c o a s t w ere a b o u t 15.6°C a t th e s u r f a c e and 12.8°C a t 61 m e t e r s . On th e n o r t h e r n p o r t i o n of th e s h e l f , A re a s I and I l a , t h i s d i f f e r e n c e was o n ly 0 .6 t o 1 .7 °C ; i n th e San D iego A re a , V I I I , th e v e r t i c a l d i f f e r ence i n c r e a s e d t o 3 .4 t o 5 .6 °C . T h i s r e g i o n had th e lo w e s t mean te m p e r a tu r e a t 61 m e te r s d e te r m in e d f o r t h i s s e a s o n . By A p r i l , May and J u n e , mean s u r f a c e t e m p e r a t u r e s had i n c r e a s e d somewhat ( 0 . 6 to 2 .2 ° C ) i n a l l a r e a s w i t h t h e g r e a t e s t ch an g es o c c u r r i n g over t h e s o u t h e r n p o r t i o n o f t h e ; f APPENDIX FIGURE C-14 L a t i t u d i n a l D i s t r i b u t i o n o f Mean T e m p e ra tu re by S e a so n s on th e M ain lan d S h e l f of S o u th e r n C a l i f o r n i a ( F i g u r e 7 9 , T ib b y , i n S te v e n s o n , 1961; and i n F ig u r e 3 . 4 , AHFtUSC, 1965). 483 484 F ig u re C-14 AREA I Do l b I H I I SEa 33Tb 3211c 3ZKa V TTTh u t r (- < t E C L U a . s ID 2 1 .1 — I 7 0 SURFACE 15.6— 6 0 — " ' 6 1 .0 METERS 10. 0— 1 50 21.1 — 7 0 SURFACE 15.6— 6 0 - u- 10.0— 50 LOME' ID SURFACE 2 1.1 — i 15.6— 6 0 — 61.0 METERS 10. 0— 1 5 0 2 1.1 — 1 7 0 SURFACE 15.6— 6 0 — 61.0 METERS 10.0— 1 5 0 JAN. FEB. MARCH APRIL MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. LATITUDINAL DISTRIBUTION OF MEAN TEMPERATURE BY SEASONS s h e l f s o u t h o f Dana P o i n t (A p p e n d ix F i g u r e C - 1 4 ) . A c o i n c i d e n t d e c r e a s e i n mean w a t e r t e m p e r a t u r e s a t 91 m e t e r s ( 1 . 7 to 3 .4 ° C ) was r e c o r d e d f o r a l l a r e a s e x c e p t A re a V I I I . V e r t i c a l d i f f e r e n c e s i n c r e a s e d i n a l l a r e a s d u r i n g t h i s s e a s o n . I n a l l a r e a s e x c e p t A rea V I I I t h i s i n c r e a s e was due t p b o t h th e i n c r e a s e i n s u r f a c e t e m p e r a t u r e and t o th e d e c r e a s e i n w a te r t e m p e r a t u r e a t d e p t h ; i n A r e a V I I I t h e i n c r e a s e i n v e r t i c a l d i f f e r e n c e s was due p r i m a r i l y t o an i n c r e a s e i n s u r f a c e t e m p e r a t u r e . The s m a l l e s t v e r t i c a l d i f f e r e n c e s w ere n o te d b e tw e e n Las P i t a s P o i n t and P o i n t Hueneme on th e S a n ta B a r b a r a s h e l f (A re a l i b ) and b e tw e e n Redondo B each and P o i n t F e rm in ( A re a s IV and V ) . T h i s ob s e r v a t i o n a lo n g w i t h c o i n c i d e n t low s u r f a c e t e m p e r a t u r e s s u g g e s t s t h a t u p w e l l i n g w as t a k i n g p l a c e i n t h e s e two a r e a s - T he e f f e c t s o f summer h e a t i n g a p p e a r i n J u l y , A u g u st an d S e p te m b e r . In t h i s s e a s o n w a te r t e m p e r a t u r e s a t a l l d e p t h s i n v e s t i g a t e d w ere t h e w a rm e st o f t h e y e a r ; v e r t i c a l d i f f e r e n c e s to 61 m e t e r s w ere t h e g r e a t e s t , 6 . 7 to 10 .0 °C (A p p e n d ix F ig u r e C - 1 4 ) . The o n ly a r e a i n w h ic h th e mean t e m p e r a t u r e s , s u r f a c e and a t d e p t h , re m a in e d s i g n i f i c a n t l y lo w e r th a n t h e r e s t o f th e s h e l f was t h e w e s t e r n p o r t i o n o f t h e n o r t h e r n s h e l f , from P o i n t C o n c e p tio n t o Las P i t a s P o i n t (A rea I and A re a I l a ) . I n d e e d , t h e mean tem - p e r a t u r e - d e p t h c u rv e fo r A re a I l a f o r t h i s s e a s o n h a s th e same g e n e r a l sh ap e and p o s i t i o n a s t h e se c o n d q u a r t e r 486 c u r v e . Both c u r v e s i n d i c a t e c o l d e r w a te r f o r a l l d e p th s th a n p r e v a i l e d i n th e w i n t e r q u a r t e r e x c e p t a t th e s u r f a c e . I n O c t o b e r , November and December t e m p e r a t u r e s a lo n g t h e n o r t h e r n p o r t i o n o f th e s h e l f , P o i n t C o n c e p tio n t o P o i n t Hueneme, w ere r e l a t i v e l y r a t h e r h i g h and u n if o r m . T e m p e ra tu re c h a r a c t e r i s t i c s w ere somewhat i r r e g u l a r o v e r th e r e s t o f t h e s h e l f . L ow est mean t e m p e r a t u r e s a t th e s u r f a c e o c c u r r e d i n A re a s IV , VI and V I I I ; t h e lo w e s t mean t e m p e r a t u r e a t 61 m e t e r s was i n A re a VI ( T ib b y , i n S t e v e n so n , 1961; and i n AHF:USC, 1 9 6 1 ). S a l i n i t y S a l i n i t y v a l u e s a r e n e a r l y u n if o r m a t a l l d e p t h s t h r o u g h o u t t h e y e a r and o v e r t h e e n t i r e m a in la n d s h e l f . More o f t e n th a n n o t , s a l i n i t y i s c o n s t a n t a t 1 5 .2 m e t e r s . The e f f e c t s o f e v a p o r a t i o n and d i l u t i o n , e i t h e r n a t u r a l or m an-made, a r e d e t e c t a b l e o n ly i n t h e u p p er 1 5 .2 m e t e r s . The l a t i t u d i n a l d i s t r i b u t i o n o f s a l i n i t y i n e a c h o f th e f o u r s e a s o n s p r e s e n t s a g e n e r a l i m p r e s s i o n o f u n i f o r m i t y , w i t h m ost v a l u e s r a n g i n g b e tw e e n 3 3 .5 0 and 3 3 .7 5 o /o o (A p p e n d ix F ig u re C - 1 5 ) . The o n ly s i g n i f i c a n t v a r i a t i o n i n t h i s p a t t e r n w as o b s e rv e d s o u th o f San D iego (A re a V U I b ) i n A p r i l , May and J u n e , when mean v a l u e s r e a c h e d 3 4 .3 0 o /o o a t t h e s u r f a c e and 3 3 .7 5 o /o o a t 6 0 .1 m e te r s ( T ib b y , i n S te v e n s o n , 1961; AHF:USC, 1 9 6 5 ). APPENDIX FIGURE C-15 L a t i t u d i n a l D i s t r i b u t i o n o f Mean S a l i n i t y by S e a so n s on th e M ainland S h e lf of S o u th e rn C a l i f o r n i a ( F ig u r e 80, T ib by, i n S te v e n so n , 1961; and i n F ig u re 3 .5 , AHFrUSC, 1965). 487 488 F ig u re C-15 AREA I l a l b n E E 3T 2 1 W n T7TTh S f fc W n v m h 3 4 .0 0 91.4 M. _ 91.4 M E T E R S 3 3 . 5 0 - SURFACE 3 3 .0 0 JAN. FEB. MARCH 3 4 .5 0 3 4 .0 0 - 9 1 .4 M E T E R S 9 1 .4 M. o > - 3 3 . 5 0 - I- SURFACE SURFACE Z < l/> 3 4 0 0 - 3 3 5 0 - J___L J I I I I i L 91.4 M. SURFACE SURFACE 91.4 M E T E R S 91.4 M. SURFACE APRIL MAY JUNE JULY AUG. SEPT. 3 4 0 0 SURFACE SURFACE 91.4 M. 91.4 M. 3 3 0 0 OCT. NOV. DEC. LATITUDINAL DISTRIBUTION OF MEAN SALINITY BY SEASONS D i s s o l v e d Oxygen D i s s o l v e d oxygen c o n c e n t r a t i o n s a r e n e a r s a t u r a t i o n i n th e s u r f a c e w a t e r s o f t h e m a in la n d s h e l f . No a r e a s a r e c o n t i n u o u s l y d e p l e t e d to l e s s th a n a b o u t 80 p e r c e n t o f s a t u r a t i o n . H ow ever, f o ll o w i n g s e v e r a l d a y s o f l i t t l e wave a c t i o n th e s u r f a c e w a t e r may hav e low oxygen v a l u e s i n such em baym ents a s S a n ta B a r b a r a , V e n t u r a , S a n ta M onica, San P ed ro and San D ie g o . V a lu e s d e c r e a s e w i t h d e p t h a s e x p e c t e d , b u t t h e mean oxygen c o n t e n t a t 91 m e te r s i n a l l a r e a s and a l l s e a s o n s w as above 4 . 0 mg/L o r a b o u t 50 p e r c e n t of s a t u r a t i o n (T a b le 3 . 2 i n AHF:USC, 1 9 6 5 ). L a t i t u d i n a l v a r i a t i o n was g r e a t e s t i n t h e f i r s t q u a r t e r o f th e y e a r (A p p e n d ix F ig u r e C -1 6 ), p a r t i c u l a r l y on th e n o r t h e r n s h e l f (A re a s I , I I and I I I ) . Oxygen c o n c e n t r a t i o n s w ere r e l a t i v e l y low ( 5 . 5 t o 6 .5 mg/L) and d e p t h v a r i a t i o n s s m a ll ( c a . 1 .0 mg/L) fro m S a n t a B a r b a r a t o Las P i t a s P o i n t (A re a I l a ) and from P o i n t Hueneme t o P o i n t Dume (A re a I I I ) . C o n d i t i o n s w e re r e l a t i v e l y u n if o r m and some w hat more oxygen ( s u r f a c e 7 . 5 to 9 . 5 ; 91 m e t e r s 4 . 8 to 6 .0 m g/L) was p r e s e n t i n th e w a t e r s o v e r th e s h e l f s o u th o f P o i n t Dume, e x c e p t f o r a d e c r e a s e o f v a l u e s a t a l l l e v e l s from C a r l s b a d t o P o i n t Loma ( s u r f a c e 7 . 5 ; 91 m e t e r s , 4 .3 m g /L ) . By th e s e c o n d q u a r t e r , A p r i l , May and J u n e , th e o v e r a l l mean oxygen c o n t e n t f o r s u r f a c e w a te r had i n c r e a s e d fro m t h e f i r s t q u a r t e r v a l u e o f a b o u t 8 mg/L t o 1 0 .5 mg/L APPENDIX FIGURE C-16 L a t i t u d i n a l D i s t r i b u t i o n o f Mean D i s s o l v e d Oxygen by S e a s o n s on t h e M a in la n d S h e l f o f S o u th e r n C a l i f o r n i a ( F i g u r e 96, T ib b y , i n S t e v e n s o n , 1961; and i n F i g u r e 3 . 9 , AHF:USC, 196.5). 490 491 F ig u re C-16 O t £ a a AREA I TTn TTh n r T 7 3C 3ZT W n 211 b S E C 2 H a 3 H b 1 0 - SURFACE 8 — 9 1 . 4 METERS 4 — SURFACE 1 0 — 8 — 6 — 9 1 . 4 METERS SURFACE 914 METERS SURFACE 8 — 6 — 9 1 . 4 METERS JAN. FEB. MARCH APRIL MAY JUNE JULY AUG SEPT OCT. NOV, DEC. LATITUDINAL DISTRIBUTION OF MEAN DISSOLVED OXYGEN BY SEASONS ( h i g h e s t s u r f a c e mean, 1 1 .3 mg/L, A rea l i b ) . T h is i n c r e a s e p r o b a b ly was a s s o c i a t e d w ith t h e i n c r e a s e i n p r im a r y p r o d u c t i o n d u r in g t h i s p e r i o d ( T ib b y , i n S te v e n s o n , 1961; AHF:USC, 1 9 6 5 ). The p a t t e r n o f l a t i t u d i n a l v a r i a t i o n noted f o r t h e f i r s t q u a r t e r p r e v a i l e d i n th e se c o n d q u a r t e r ( F i g u r e 3 7 ); w h e r e in , th e lo w e s t mean s u r f a c e v a l u e s and the l e a s t d e p th v a r i a t i o n o c c u r r e d i n A re a s I l a , I I I and V IIc. S u r f a c e oxygen d e c r e a s e d i n t h e t h i r d q u a r t e r ( J u l y , A ugust and S e p te m b e r) by a b o u t 1 t o 3 mg/L d ep en d in g on t h e a r e a i n v o l v e d (A p p e n d ix F ig u re C - 1 6 ) . At d e p th ( 9 1 .6 m e te r s ) v a l u e s re m a in e d a b o u t th e same, c a . 4 .5 to 6 .5 mg/L, a s th e p r e v i o u s q u a r t e r e x c e p t f o r a 1 .5 mg/L i n c r e a s e o b s e rv e d i n A rea V i l l a (La J o l l a t o P o i n t Lom a). I n th e l a s t q u a r t e r ( O c to b e r , November and Decem b e r ) s u r f a c e oxygen c o n c e n t r a t i o n s w ere u n i f o r m l y m oderate (7 to 8 mg/L) and v e r t i c a l d i f f e r e n c e s s m a ll (2 to 3 mg/L) o v e r th e e n t i r e s h e l f (A p p en d ix F ig u re C - 1 6 ) . L a t i t u d i n a l v a r i a t i o n was t h e g r e a t e s t o ver t h e s o u t h e r n a r e a d u r in g t h i s s e a so n (T ib b y , i n S te v e n s o n , 1961; and i n AHFrUSC, 1 9 6 5 ). Common I n o r g a n i c N u t r i e n t s : P h o s p h a te , S i l i c a t e and N i t r a t e P h o s p h a te c o n c e n t r a t i o n s were r e l a t i v e l y u n ifo rm o v er t h e e n t i r e s h e l f i n w i n t e r (A ppendix F ig u re C -1 7 ). The mean s u r f a c e v a l u e s f o r a l l a r e a s w ere a b o u t 0 .0 5 0 mg/L, APPENDIX FIGURE C-17 L a t i t u d i n a l D i s t r i b u t i o n o f Mean P h o s p h a te by S e a s o n s on th e M a in la n d S h e l f o f S o u th e rn C a l i f o r n i a ( F i g u r e 113, T ib b y , i n S te v e n s o n , 1961; and i n F ig u r e 3 . 1 4 , AHF:USC, 1 965). 493 F ig u re C-17 494 no ib m m AREA 3 T 31 T S U o M b T Z K c M ia 2KC 0.200 91.4 0 .1 5 0 - 61 . 0 0.100- 30.5 0 . 0 5 0 - 0.000 JAN FEB. MARCH s ot E o* CL 0 .2 5 0 0.200- 91.4 0 .1 5 0 - 61.0 30.5 0.100- 0 .0 5 0 - 0.000 0.200 « .4 «.o 0 .1 5 0 - 0.100- 0 .0 5 0 - • 0. 000— 1 APRIL MAY JUNE JULY AUG. SEPT. 0.200 0.150—| 0. 100 0.050-1 0.000 J L J I L 9 1 .4 OCT. NOV. DEC. LATITUDINAL DISTRIBUTION OF MEAN PHOSPHATE BY SEASONS 495 w i t h l i t t l e i n c r e a s e t o d e p t h o f 3 0 .5 m e t e r s . Below t h i s d e p th i n m ost a r e a s c o n c e n t r a t i o n s i n c r e a s e d , w i t h means o f a b o u t 0 .1 5 0 t o 1 .7 5 0 mg/L a t 91 m e t e r s ; a l e s s e r i n c r e a s e was n o te d i n A re a s I and I I . A p r i l , May and J u n e w ere c h a r a c t e r i z e d by a s u b s t a n t i a l i n c r e a s e i n p h o s p h a te a t s u b s u r f a c e l e v e l s (A p p en d i x F ig u r e C - 1 7 ) . Mean am ounts d e c r e a s e d a t t h e s u r f a c e i n many a r e a s (A p p e n d ix F i g u r e C - 1 7 ) . C o n s e q u e n t l y , i n c o n t r a s t t o t h e p r e v i o u s q u a r t e r , t h e s h a r p e s t v e r t i c a l g r a d i e n t s w ere i n t h e u p p e r 3 0 .5 m e te r s o f t h e w a t e r colum n. Below t h i s d e p t h v e r t i c a l d i f f e r e n c e s were l e s s p ro n o u n c e d . N e v e r t h e l e s s , t h e h i g h e s t v a l u e s o b s e rv e d d u r i n g th e y e a r , 0 .1 7 5 t o 0 .2 0 0 mg/L o c c u r r e d d u r i n g t h i s p e r i o d a t 91 m e t e r s . D a ta f o r t h e summer q u a r t e r a r e l i m i t e d . The a v a i l a b l e o b s e r v a t i o n s i n d i c a t e a c o n t i n u a t i o n o f t h e s e c ond q u a r t e r p a t t e r n on t h e n o r t h e r n s h e l f w e s t o f S a n t a B a r b a r a and a d e c r e a s e i n s u r f a c e v a l u e s i n some a r e a s o f t h e s h e l f s o u t h o f N e w p o rt. The d i s t r i b u t i o n o f p h o s p h a te i n t h e f a l l re s e m b le d t h a t i n th e w i n t e r q u a r t e r (A p p e n d ix F ig u r e C - 1 7 ) , b u t t h e g r e a t e s t d i f f e r e n c e s fro m a r e a t o a r e a w ere o b s e r v e d , p a r t i c u l a r l y i n s u r f a c e v a l u e s . V e r t i c a l d i f f e r e n c e s w ere th e s m a l l e s t . Mean s u r f a c e v a l u e s g e n e r a l l y r a n g e d from 0 .0 2 5 to 0 .0 5 0 mg/L e x c e p t o v e r th e San P e d ro Bay s h e l f w here t h e y were h i g h e r ( 0 .0 5 0 t o 0 .0 7 5 m g /L ). P h o s p h a te c o n t e n t 496 te n d e d to be h i g h e r o v er th e P o i n t C o n c e p tio n and San P ed ro s h e l v e s ( a b o u t 0 .150 mg/L) and low er s o u th o f C a r ls b a d (T ib b y and B a r n a r d , 1962; T ib b y , i n S te v e n s o n , 1961, and i n AHF:USC, 1 9 6 5 ). The g e n e r a l l a t i t u d i n a l d i s t r i b u t i o n o f s i l i c a t e i n w i n t e r i s one o f low v a l u e s a lo n g th e s h e l f b e tw e e n P o i n t C o n c e p tio n and Las P i t a s P o i n t (A re a s I and I l a ) , h ig h v a l u e s b etw een Las P i t a s P o i n t and P o i n t Ferm in (A re a s l i b to V) and i n t e r m e d i a t e v a l u e s o v er th e s o u th e r n s h e l f (A p p e n d ix F ig u r e C - 1 8 ) . Most v a l u e s f o r s i l i c a t e i n th e u p p e r 3 0 .5 m e te r s a r e b e tw e e n 0 .2 5 and 0 .7 5 mg/L e x c e p t over t h e n o r th e rn m o s t s e c t i o n o f t h e s h e l f , w h ere th e y a r e lo w e r, 0 .1 5 t o 0 .5 5 mg/L. The lo w e s t mean s i l i c a t e v a l u e s ( 0 .7 5 to 0 .9 0 mg/L) a t 91 m e te r s w ere a ls o on th e n o r t h e r n p o r t i o n o f th e m a in la n d s h e l f . Maximum v a l u e s o f 2 .0 0 to 2 .2 5 mg/L were o b s e rv e d b e tw e e n P o i n t Las P i t a s and P o i n t F e rm in . S o u th o f P o i n t Ferm in v a l u e s a t 91 m e te r s were a b o u t 1.50 t o 1 .7 5 mg/L. In t h e s p r i n g q u a r t e r s i l i c a t e c o n t e n t i n c r e a s e d m a rk e d ly a t s u b s u r f a c e l e v e l s r e a c h i n g a t l e a s t 2 .5 0 mg/L and, i n th e a r e a from N ewport Beach t o La J o l l a , and p e r h ap s f u r t h e r s o u t h , n e a r l y 3 .0 0 mg/L (A pp en d ix F ig u r e C-18). H ow ever, s u r f a c e s i l i c a t e s g e n e r a l l y re m a in e d b elo w 0 .5 0 mg/L e x c e p t i n th e r e g i o n b etw een P o i n t Las P i t a s and P o i n t Dume where t h e y ra n g e d from 0 .7 5 t o 0 .8 5 mg/L. Only a few a r e a s and d e p t h s were sam pled d u r in g t h e summer m o n th s, b u t' APPENDIX FIGURE C-18 L a t i t u d i n a l D i s t r i b u t i o n of Mean S i l i c a t e by Season s on th e M ainland S h e lf of S o u th e rn C a l i f o r n i a (F ig u re 114, T ibby, in S te v en so n , 1961; and i n F ig u re 3 .1 5 , AHFrUSC, 1965). 497 S iO g (mg/L) 498 F ig u re C-18 2 .5 0 - 2.00 1.50—| 1 .0 0 0 .5 0 -1 0 AREA I l o l b 1 E Z 1 SE a 301 b 2Ec 2E o 3ZIEb JL. 1___>1 1 1 ___I___I___I___I___I___I__ 91.4 £ UJ b — UJ X 3 .0 0 2 . 5 0 - 61.0 METERS 2.00 - 1 .5 0 - 1 .00— 0 . 5 0 - 0 M. 2.00 1 .5 0 - 91.4 M ETER S 61.0 M E TE R S 1 .00- 3 0 .5 METERS 0 METERS 0 . 5 0 - 2.00 914 . 5 0 - 1 .00- 0 .5 0 )- JAN. FEB. MARCH APRIL MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. LATITUDINAL DISTRIBUTION OF MEAN SILICATE BY SEASONS 499 c o n d i t i o n s i n t h i s s e a s o n p r o b a b l y w ere i n t e r m e d i a t e b e tw een t h o s e of t h e s p r i n g and f a l l . The l a t i t u d i n a l p a t t e r n i n O c to b e r , November and D ecem ber r e s e m b le d t h a t i n th e w i n t e r , e x c e p t t h a t v a l u e s w ere lo w e r b e tw e e n 61 and 91 m e t e r s b e tw e e n S a n ta B a r b a r a and Hueneme (A p p en d ix F i g u r e C - 1 8 ) . From P o i n t C o n c e p tio n t o Las P i t a s P o i n t s i l i c a t e i n t h e u p p e r 91 m e te r s was a l s o low , 0 . 5 0 - 1 . 1 5 mg/L (T ib b y and B a r n a r d , 1962; T ib b y , i n S te v e n s o n , 1961 and i n AHF:USC, 1 9 6 5 ). A t t h e s u r f a c e c o n c e n t r a t i o n s o f n i t r a t e ra n g e d from 0 . 0 1 t o 0 .1 5 mg/L and a t 91 m e t e r s fro m 0 .0 6 t o 0 .4 0 mg/L. I n th e f i r s t q u a r t e r of t h e y e a r , t h e mean s u r f a c e n i t r a t e s i n a l l a r e a s w ere from 0 . 0 4 to 0 . 0 8 mg/L (maximum, 0 .1 9 ; minimum, 0 . 0 1 ) , and a t 91 m e t e r s t h e r e was an i n c r e a s e w i t h d e p t h to v a l u e s b e tw e e n 0 .2 8 and 0 .3 5 mg/L (maximum, 0 .0 4 ; minimum, 0 . 5 5 ) . A lo n g th e s o u t h e r n h a l f o f t h e c o a s t t h e r e was a te n d e n c y f o r somewhat h i g h e r v a l u e s and g r e a t e r r a n g e s w i t h d e p th b e lo w 3 0 .5 m e t e r s . Mean s u r f a c e v a l u e s i n c r e a s e d i n s p r i n g t o b e tw e e n 0 .0 5 and 0 .1 3 mg/L i n t h e r e g i o n b e tw e e n P o i n t C o n c e p tio n to Las P i t a s P o i n t . To t h e s o u t h , s u r f a c e means w ere some w hat g r e a t e r ( 0 .0 2 1 t o 0 .0 3 2 ) and th e a b s o l u t e r a n g e was l a r g e r ( 0 .1 9 t o 0 . 3 7 ) . The h i g h e s t s u b s u r f a c e v a l u e s w ere o b s e rv e d i n th e s p r i n g , p a r t i c u l a r l y on th e n o r t h e r n p o r t i o n o f t h e s h e l f . Mean v a l u e s a t 91 m e t e r s r e a c h e d 0 .4 0 mg/L. 500 Not e n o u g h d a t a a r e a v a i l a b l e f o r th e summer to a l low d e s c r i p t i o n o f t h i s v a r i a b l e d u r i n g t h i s s e a s o n - I n th e f a l l s u r f a c e means ra n g e d fro m 0 .0 1 t o 1 .1 5 m g/L and i n d i v i d u a l v a l u e s ra n g e d fro m 0 . 0 1 t o 0 .3 7 mg/L. V a r i a b i l i t y i n n i t r a t e b e tw e e n 61 and 91 m e t e r s was from 0 . 0 2 to 0 .4 3 mg/L. I n t h e n o r t h e r n a r e a means w ere from 0 . 2 2 to 0 .3 0 mg/L a t t h e s e d e p t h s ; v a l u e s w ere somewhat lo w e r in th e w a t e r s o v e r th e s o u t h e r n h a l f o f t h e s h e l f b e tw e e n 61 and 91 m e te r s ( T ib b y , i n S t e v e n s o n , 1961; and i n AHP:USC, 1965) . APPENDIX D A REVIEW OF THE BENTHIC MACROFAUNA OF THE MAINLAND SHELF T h i s a p p e n d ix i n c l u d e s a r e v ie w o f th e know ledge o f t h e b e n t h i c m a c ro fa u n a o f t h e m a in la n d s h e l f g a in e d as th e r e s u l t o f t h e A l l a n Hancock F o u n d a tio n S u rv ey o f th e m ain l a n d s h e l f . S in c e th e o f f s h o r e b e n t h i c m a c ro fa u n a (d e e p e r t h a n 10 .1 m e te r s ) and th e n e a r s h o r e b e n t h i c m a c ro fa u n a (2 t o 1 0 .1 m e te r s ) w ere sam p led and a n a ly z e d s e p a r a t e l y , t h e y a r e re v ie w e d s e p a r a t e l y h e r e . S u b d i v i s i o n i n t o t h e s e two d e p th zo n es r e s u l t s fro m t e c h n i c a l l i m i t a t i o n s . O f f s h o r e s a m p le s w ere ta k e n fro m t h e R,/V V e le ro IV and n e a r s h o r e sam p les w ere ta k e n fro m t h e m otor la u n c h o f th e r e s e a r c h v e s s e l . The O f f s h o r e F auna, O ver 10 M e te rs E s t i m a t e s o f th e e x t e n t o f t h e b e n t h i c m ac ro fa u n a o f t h e m a in la n d s h e l f a r e v a r i o u s . B ased on t h e sam p les c o l l e c t e d d u r in g t h e A l l a n Hancock F o u n d a tio n S u rv e y , H artm an ( i n S te v e n s o n , 1961) e s t i m a t e s t h e c o m p o s itio n o f t h e b e n t h i c m a c ro fau n a a s c o n s i s t i n g o f o v e r 1200 s p e c i e s . ;B arn ard (1 9 6 3 , T a b le 13) e s t i m a t e d t h i s v a l u e a t 1620 I s p e c i e s . I n d i v i d u a l s a m p le s by t h e OPB a v e r a g e d 7 8 .5 502 s p e c i e s ( b a s e d on 118 sa m p le s; T a b le I I I , B a rn a rd , H artm an and J o n e s , 1 9 5 9 ). T h e se same s a m p le s a v e r a g e d 697 s p e c i mens p e r sam ple ( r a n g e , 89 - 2909) e q u i v a l e n t to a mean p o p u l a t i o n d e n s i t y o f a p p r o x i m a te ly 3500 a n im a ls p e r s q u a re m e t e r . B a r n a r d and G iv en (1961, T a b le 1) g i v e a m ore p r e c i s e f i g u r e , 3903,/ s q u a r e m e te r, b a s e d on t h e s t r a t i f i e d s a m p l e - s e t o f 176 OPB sa m p le s. F o u r ta x o n o m ic c a t e g o r i e s - - p o l y c h a e t o u s a n n e l i d s , c r u s t a c e a n a r t h r o p o d s , e c h in o d e rm s and m o l l u s k s - - w e r e th e m o st a b u n d a n t e le m e n ts i n th e s a m p le s . P o l y c h a e t e s a r e th e most w i d e l y d i s t r i b u t e d g ro u p o f i n v e r t e b r a t e a n im a ls i n th e s u r v e y ; th e y o u tr a n k a l l o t h e r g ro u p s i n number o f s p e c i e s and number o f sp e c im e n s. B a r n a r d (1 9 6 3 ; T a b le 13) e s t i m a t e s t h a t sa m p le s fro m th e o f f s h o r e r e g i o n c o n t a i n e d 700 d i s t i n c t p o l y c h a e t e s p e c i e s ; e a r l i e r H artm an ( i n S te v e n s o n , 1961) e s t i m a t e d over 450 s p e c i e s . The mean number o f p o l y c h a e t e s p e c i e s p e r sam ple ( 0 .2 0 s q u a r e m e te r s ) f o r sam ples fro m th e o u t e r s h e l f i s 39 ( B a r n a r d , 1963, T a b le 1 2 ); t h i s i s s u b s t a n t i a l l y h ig h e r t h a n th e v a l u e s f o r th e o t h e r t h r e e g r o u p s - - c r u s t a c e a n s , m o llu s k s and e c h in o d e rm s . P o l y c h a e t e s have th e h i g h e s t p o p u l a t i o n d e n s i t y o f a l l g ro u p s , a mean o f 1424 p o l y c h a e t e s p e r s q u a re m e te r (176 s a m p le s ; B a r n a r d and G iv en , 19 6 1 , T a b le 1 ) . C r u s t a c e a n s , e s p e c i a l l y a m p h ip o d s, c o m p rise th e se c o n d l a r g e s t g ro u p n u m e r i c a l l y . A lth o u g h th e y se ld o m 503 amount t o more th a n 5 p e r c e n t o f t h e s t a n d i n g c ro p i n a sa m p le , th e y g e n e r a l l y a c c o u n t f o r a b o u t 25 p e r c e n t o f th e i n d i v i d u a l s (AHFsUSC, 1 9 6 5 ). B a r n a r d (1 9 6 3 , T a b le 13) e s t i m a t e s th e t o t a l number o f c r u s t a c e a n s p e c i e s c o l l e c t e d from t h e s h e l f a t 350; t h i s g ro u p a v e r a g e s 28 s p e c i e s p e r sam ple ( B a r n a rd , 1963, T a b le 1 2 ) . The c r u s t a c e a n mean p o p u l a t i o n d e n s i t y c a l c u l a t e d on t h e b a s i s o f 176 sa m p le s i s 1352 i n d i v i d u a l s p e r s q u a r e m e te r (B a rn a rd and G iv en , 1961, T a b le 1 ) . Gammarid am phipods co m p rise th e m ost im p o r t a n t s u b d i v i s i o n o f c r u s t a c e a n s w i t h a mean number o f i n d i v i d u a l s p e r s q u a r e m e te r o f 695; th e am phipods a r e f o llo w e d i n o r d e r by th e o s t r a c o d s , 437,/m2 , th e cum aceans, 78,/m3 , t h e t a n a i d s , 46/m2 , th e i s o p o d s , 26/m 2 , b r a c h y u r a n and anom uran c r a b s , 23,/m2 , s h r im p s , 13/vnP , c i r r i p e d s , 10,/m3 , c a p r e l l i d s , 9/m3 , n e b a l i a n s , 9/m2 , and m y sid s, 2.7,/m? . E c h in o d e rm s, e s p e c i a l l y o p h i u r o i d s , form an im p o r t a n t g ro u p on t h e s h e l f i n d e p th s g r e a t e r t h a n 10 m e t e r s . Only a b o u t 70 s p e c i e s a r e Known fro m t h i s a r e a ( B a r n a rd , 1963, T a b le 1 3 ) , b u t some o f t h e s e a r e c o l l e c t e d i n n e a r l y e v e ry s a m p le . The mean number o f s p e c i e s p e r s a m p le i s 5 (B a r n a r d , 1963, T a b le 1 2 ) . E ch in o d erm s a v e r a g e d 532 i n d i v i d u a l s p e r s q u a r e m e te r (B a rn a rd and G iv e n , 1961, T a b le 1). M o llu sk s c o n s t i t u t e th e f o u r t h g ro u p i n o r d e r o f 504' i m p o r t a n c e , b u t a r e l e s s p ro m in e n t th a n m ig h t be a n t i c i p a t ed (G. J o n e s , 1 9 6 4 ). B a rn a rd (1 9 6 3 , T a b le 13) e s t i m a t e d t h a t th e p r o j e c t sa m p le s c o l l e c t e d 300 s p e c i e s o f m o l l u s k s . A c c o rd in g t o G. J o n e s (1 9 6 4 ) m o llu s k s p e c i e s a v e r a g e d 1 5 .2 p e r sam ple ( r a n g e , 0 - 43) or 1 6 .5 p er c e n t ( r a n g e , 0 - 3 4 .0 ) o f th e mean t o t a l number o f s p e c i e s o f a l l g r o u p s p e r sa m p le . The o v e r a l l p o p u l a t i o n d e n s i t y o f m o llu s k s i s 470 i n d i v i d u a l s p e r s q u a r e m e te r ( B a r n a r d and G iv e n , 1961, T a b le 1 ) . B ased on a s e t o f 335 s a m p le s G. J o n e s (1 9 6 4 ) c a l c u l a t e d a somewhat lo w e r m ean, 3 6 8 .4 s p e c im e n s/m 2 ( r a n g e , 0 - 4 , 1 1 2 ) ; t h i s r e p r e s e n t s 1 2 .0 p e r c e n t ( r a n g e , 0 - 5 0 .5 p e r c e n t ) o f th e mean t o t a l number o f m a c r o f a u n a l i n d i v i d u a l s p e r s q u a r e m e te r i n t h e s e s a m p le s . A l l o t h e r p h y l o g e n e t i c g ro u p s w e re l e s s w e l l r e p r e s e n t e d on t h e s h e l f . B a rn a rd (1 9 6 3 , T a b le 13) e s t i m a t e d t h a t a b o u t 200 s p e c i e s w ere c o l l e c t e d w h ic h b e lo n g t o o t h e r t a x a ( i n v e r t e b r a t e s and lower c h o r d a t e s ) ; t h e s e had a mean p o p u l a t i o n d e n s i t y o f 125/m3 . I n c lu d e d w e re r e p r e s e n t a t i v e s o f t h e f o l l o w i n g g r o u p s : b r a c h i o p o d s ( e s p e c i a l l y G l o t t i d i a ) , b r y o z o a n s ( e s p e c i a l l y C e l l u l a r i a ) , c o e l e n t e - r a t e s ( p a r t i c u l a r l y c e r i a n t h a r i a n s ) , e c h i u r o i d s ( p a r t i c u l a r l y L i s t r i o l o b u s ) , c e p h a l o c h o r d a t e s ( e s p e c i a l l y B r a n c h io s to m a ) , n e m a to d e s , n e m e r t e a n s , p h o r o n i d s , p o l y c l a d s and r h a b d o c o e l s ( p l a t y h e l m i n t h s ) and p y c n o g o n id s . Two s p e c i e s d e s e r v e s p e c i a l m e n tio n ; t h e s e a r e th e 505 : i n a r t i c u l a t e b r a c h io p o d G l o t t i d i a a l b i d a and t h e e c h i u r o i d , worm L i s t r i o l o b u s p e l o d e s . G l o t t i d i a was c o l l e c t e d i n 4 9 .5 ;p er c e n t o f 382 s a m p le s a n a ly z e d by J o n e s and B a rn a rd (1963) ( n o t i n 60 p er c e n t o f t h e s h e l f s a m p le s as s t a t e d i n AHF:USC, 1 9 6 5 ). The mean p o p u l a t i o n d e n s i t y o f t h i s s p e c i e s on t h e o f f s h o r e p a r t o f th e s h e l f i s 3 l/m 3 (176 sam p l e s , J o n e s and B a r n a r d , 1 9 6 3 ) . The worm L i s t r i o l o b u s p e lo d e s ( f a m i l y E c h i u r i d a e ) i s not w id e s p r e a d on th e s h e l f b u t form s an i m p o r t a n t e le m e n t in one a r e a , t h e S a n ta B a r b a r a s h e l f ( B a r n a r d and H artm an, 1 9 5 9 ). P o p u l a t i o n d e n s i t y ( i n d i v i d u a l s per s q u a r e m e te r ) p r o v id e s a b a s i s f o r the d e t e r m i n a t i o n o f th e n u m e r i c a l l y i m p o r t a n t s p e c i e s i n an a r e a . Two d i f f e r e n t a n a l y s e s have b e e n made f o r th e o u t e r p o r t i o n of t h e s h e l f ; t h e f i r s t , a p r e l i m i n a r y l i s t i n g based on 119 s a m p le s , i s p r e s e n t e d by B a r n a r d , Hartman a n d Jo n e s (1 9 5 9 , T a b l e s IX ); t h e se c o n d , b a s e d on t h e 176 sam ple s e t , i s shown i n T a b le D - l (T a b le 15, B a r n a r d , 1963; a l s o T a b le 2, H artm an , B a rn a rd and J o n e s , 1 9 6 0 ). P o l y c h a e t e s c o n s t i t u t e 50 p e r c e n t (1 1 o f 22) o f t h e s p e c i e s l i s t e d ; f iv e c r u s t a c e a n s a r e in t h e l i s t ; t h r e e s p e c i e s a r e m o llu s k s ; two a r e e c h in o d e rm s and one i s th e b r a c h io p o d G l o t t i d i a a l b i d a . The o p h i u r o i d A m phiodia u r t i c a r a n k s f i r s t w ith a mean p o p u l a t i o n d e n s i t y o f 422/m3 , f a r more t h a n any o t h e r s p e c i e s . Second a t 112/m3 i s th e s m a l l p o l y c h a e t e P r i o n o s p i o m a lm g re n i. The 506 APPENDIX TABLE D -l The M ost A bundant A n im als o f t h e O f f s h o r e B ottom A r e a s , D eep er th a n 1 0 .1 M e te rs (T a b le 2 , H artm an , B a rn a rd and J o n e s , 1 9 6 0 ). Name o f Animal F r e q u e n c y /S q u a r e M e te r A m phiodia u r t i c a 422 P r i o n o s p i o m alm greni 112 A x in o p s id a s e r r i c a t a 66 P h o t i s s p . 59 P a ra p h o x u s b i c u s p i d a t u s 56 P r i o n o s p i o p i n n a t a 5 5 P e c t i n a r i a c a l i f o r n i e n s i s 53 T h a ry x t e s s e l a t a 52 A rap elisca b r e v i s i m u l a t a 47 A m p h ip h o lis squam ata 44 H a p lo s c o lo p lo s e l o n g a t u s 42 L u m b r in e r is c r u z e n s i s 39 B i t t i u m sp . 37 C h l o e i a p i n n a t a 36 P a r a o n i s g r a c i l i s 35 A m p e lisc a c r i s t a t a 32 R o c h e f o r t i a sp . 30 H ete ro p h o x u s o c u l a t u s 29 G l o t t i d i a a l b i d a 28 D o r v i l l e a a r t i c u l a t a 28 C o s s u r a Candida 27 APPENDIX TABLE D -l (C o n tin u e d ) Name o f A nim al A c r o id e s c o lu m b ia e S p io p h a n e s m i s s i o n e n s i s F r e q u e n c y /S q u a r e M e te r 25 25 508 ; s m a ll p e le c y p o d A x i n o p s is s e r r i c a t u s (= A x in o p s id a s e r r i c a t a ) i s t h i r d w ith o n l y 66/m2 . V a lu e s d e c l i n e m ore s lo w ly t h r o u g h th e r e m a in d e r o f th e l i s t and t h e 22nd ra n k e d s p e c i e s i s p r e s e n t a t 25/m2 o r a b o u t l / l 3 o f t h e p o p u l a t i o n o f A m p h io d ia u r t i c a , th e f i r s t ra n k e d s p e c i e s . The O f f s h o r e A s s o c i a t i o n s More t h a n 20 m a c r o f a u n a l b e n t h i c a s s o c i a t i o n s have b e e n r e c o g n i z e d on t h e m a in la n d s h e l f o f s o u t h e r n C a l i f o r n i a b u t o n l y a few o f t h e s e have b e e n d e s c r i b e d i n d e t a i l . Pew o f t h e s e a s s o c i a t i o n s h av e more th a n a l i m i t e d a r e a l d i s t r i b u t i o n . The m a jo r s h e l f a s s o c i a t i o n s h a v e b e e n mapped by B a rn a rd ( [ a ] , i n S t e v e n s o n , 1961, F i g u r e s 4 6 - 4 9 ) ; t h e s e maps a r e p r e s e n t e d a s A p p e n d ix F i g u r e s D - l , D-2, D-3 and D -4 . D e s c r i p t i o n s o f th e m a in la n d s h e l f a s s o c i a t i o n s a r e i n c l u d e d i n th e f o l l o w i n g s o u r c e s : AHF:USC, 1965; B a rn a rd ( a ) , i n S t e v e n s o n , 1961; B a r n a r d , 1963; B a r n a r d and H artm an, 1959; B a r n a r d , H artm an and J o n e s , 1 9 5 9 ; B a rn a rd and Z ie s e n h e n n e , 1961; H a rtm a n , 1955, 1956, 1960; G. J o n e s ( c ) , i n S t e v e n s o n , 1961; G. J o n e s , 1964, 1965; and T ib b y and B a r n a r d , 1964. O p h iu r o id a s s o c i a t i o n s p o p u l a t e a b o u t 26 p e r c e n t o f t h e s h e l f ( B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ) . I n c l u d e d a re th e e x t e n s i v e l y d i s t r i b u t e d a s s o c i a t i o n s " d o m in a te d " by th e ■ sm ooth r e d o p h i u r o i d A m phiodia u r t i c a and s e v e r a l c l o s e l y r e l a t e d a s s o c i a t i o n s . T h e i r g e n e r a l d i s t r i b u t i o n i s mapped APPENDIX FIGURE D - l The D i s t r i b u t i o n o f B e n t h i c M a c r o f a u n a l A s s o c i a t i o n s on t h e M a in la n d S h e l f , P o i n t A r g u e l l o ( P o i n t C o n c e p tio n ) t o S a n ta B a r b a r a ( F i g u r e 4 6 , B a r n a r d [ a] , i n S te v e n s o n , 1 9 6 1 ). N o te : Only t h e m a jo r ( w id e ly d i s t r i b u t e d ) a s s o c i a t i o n s a r e m apped; t h e sm o o th ed c u r v e s o f t h i s map p r e s e n t a somewhat i d e a l i z e d v e r s i o n o f t h e s e d i s t r i b u t i o n s o b s c u r i n g s l i g h t l y m ore r e t i c u l a t e d p a t t e r n s . 509 30* id r c o * o o ' s c r 40' FT. ARGUELLO 4 tf & Diopotro Amphiodio-Cardito Lntriolobw Nothria-Ttllina iT A tu T i rntn PT. ARGUELLO TO SANTA BARBARA C O M M U N IT IE S era £ >s (D 0 1 p U ( M O APPENDIX FIGURE D-2 The D i s t r i b u t i o n o f B e n th ic M a c ro fa u n a l A s s o c i a t i o n s on t h e M a in la n d S h e l f , S a n ta B a r b a r a t o P o i n t Dame ( F ig u r e 47, B a rn a rd t a ] , i n S te v e n s o n , 1 9 6 1 ). N o te : Only t h e m ajo r ( w id e ly d i s t r i b u t e d ) a s s o c i a t i o n s a r e mapped; t h e sm oothed c u r v e s o f t h i s map p r e s e n t a somewhat i d e a l i z e d v e r s i o n o f t h e s e d i s t r i b u t i o n s o b s c u r i n g s l i g h t l y more r e t i c u l a t e d p a t t e r n s . The a s s o c i a t i o n l i s t e d i n th e le g e n d as tT C h lo e la n i s t h e P e c t i n a r i a - C h l o e i a a s s o c i a t i o n . 511 1 VENTUHA A m p h io a ia C o r d ilo L istrio lo b u s N o th n o - T e tim a A m phiodia SANTA BARBARA TO POINT DUME COMMUNITIES F ig u re D-2 O l M W APPENDIX FIGURE D-3 The D i s t r i b u t i o n o f B e n th ic M a c ro fa u n a l A s s o c i a t i o n s on th e M a in la n d S h e l f , P o i n t Dame to New port ( F ig u r e 4 8 , B a rn a rd [a], i n S te v e n s o n , 1 9 6 1 ). N o te : Only t h e M ajor (W id ely d i s t r i b u t e d ) a s s o c i a t i o n s a r e mapped; t h e sm oothed c u r v e s o f t h i s map p r e s e n t a somewhat i d e a l i z e d v e r s i o n o f t h e s e d i s t r i b u t i o n s o b s c u r i n g s l i g h t l y more r e t i c u l a t e d p a t t e r n s . The a s s o c i a t i o n l i s t e d i n th e le g e n d as "C h l o e i a " i s th e P e c t i n a r i a - C h l o e i a a s s o c i a t i o n . 513 A m p h io d ia POINT DUME TO NEWPORT A m p h io p lu s C O M M U N IT IE S N o t h r i o - T a l li n a F ig u r e D-3 U l APPENDIX FIGURE D-4 The D i s t r i b u t i o n o f B e n th ic M a c ro fa u n a l A s s o c i a t i o n s on th e M ain la n d S h e l f , N ew port t o M exico ( F ig u r e 4 9 , B a rn a rd la] , i n S te v e n s o n , 1 9 6 1 ). N o te : Only t h e m ajor ( w id e ly d i s t r i b u te d ) a s s o c i a t i o n s a r e mapped; th e sm oothed c u rv e s o f t h i s map p r e s e n t a somewhat i d e a l i z e d v e r s i o n o f t h e s e d i s t r i b u t i o n s o b s c u r i n g s l i g h t l y more r e t i c u l a t e d p a t t e r n s . 515 NEWPORT TO MEXICO F ig u r e D-4 L n M O ' 517 i n (A ppendix F i g u r e D -5) F i g u r e 1, B a r n a r d and Z i e s e n h e n n e , ; 1 9 6 1 ); p a r t i c u l a r r e g i o n a l e x p r e s s i o n s o f t h i s d i s t r i b u t i o n a r e shown i n A p p e n d ix F i g u r e s D - 6 , D-7, D-8 and D-9 ( F i g u r e s 2 - 5 , B a rn a rd and Z ie s e n h e n n e , 1 9 6 1 ). T he A m p h i o d i a - C a r d it a A s s o c i a t i o n On t h e n o r t h e r n p o r t i o n o f th e m a in la n d s h e l f , P o i n t C o n c e p ti o n to Hueneme S u b m arin e Canyon (A re a s I and I I ) , A m phiodia u r t i c a i s a s s o c i a t e d w i t h t h e p e le c y p o d m o llu s k C a r d i t a v e n t r i c o s a (A p p en d ix F i g u r e D -6) . T h is a s s o c i a t i o n i s a l o c a l m o d i f i c a t i o n o f t h e more e x t e n s i v e a s s o c i a t i o n " d o m in a te d ” s o l e l y by th e o p h i u r o i d A m phiodia u r t i c a . A c c o r d in g t o B a rn a rd a n d Z ie s e n h e n n e (1 9 6 1 ) th e A m p h io d ia- C a r d i t a a s s o c i a t i o n c o v e r s a b o u t 11 p e r c e n t o f t h e a r e a o f t h e m a in la n d s h e l f g e n e r a l l y w i t h i n t h e d e p t h r a n g e o f 60 t o 110 m e t e r s . S i x t e e n r e p r e s e n t a t i v e s e d im e n t sa m p le s w i t h i n t h i s a s s o c i a t i o n had an a v e r a g e m e d ia n d ia m e t e r o f 0 .0 5 1 mm ( r a n g e , 0.011 - 0 .1 0 6 mm) and a mean p e r c e n t sand o f 3 7 .0 ( r a n g e , 1 .0 - 7 5 .0 p e r c e n t ) . The mean num ber o f s p e c i e s / s a m p l e , 92, an d th e m ean number o f s p e c i m ens/m 2, 3 4 1 6 , r e p o r t e d f o r t h i s a s s o c i a t i o n w ere b a s e d on 11 r e p r e s e n t a t i v e s a m p le s ( B a r n a r d and Z i e s e n h e n n e , 1 9 6 1 ). The mean s t a n d i n g c r o p In t h i s a s s o c i a t i o n i s 237 g,/m3 ( B a rn a rd [ a ] , I n S te v e n s o n , 1 9 6 1 ) . The A m p h io d ia - C a r d i t a a s s o c i a t i o n i s t h e p r o m in e n t f e a t u r e o f t h e b i o t a o f th e P o i n t C o n c e p tio n s h e l f b e tw e e n APPENDIX FIGURE D-5 A Map o f th e Southern- C a l i f o r n i a n M ain lan d S h e l f ( d e f i n e d by th e 50 fa th o m c o n to u r = 91-4 m e te r c o n to u r ) Showing t h e A re a s P o p u l a t e d by O p h iu r o id A s s o c i a t i o n s . A r e a s Shown i n A ppendix F i g u r e s D -6 , D -7, D-8 and D -9. ( F ig u r e 1, B a rn a rd and Z ie s e n h e n n e , 1961). 518 F ig u r e D-5 519 SOUTHERN CALIFORNIA • o APPENDIX FIGURE D -6 f A Map Showing th e D i s t r i b u t i o n o f th e A m p h io d ia- C a r d i t a A s s o c i a t i o n (Shaded w i t h L in e s ) on t h e S a n ta B a r b a r a S h e l f and th e B re a k B etw een t h e A m p h io d ia- C a r d i t a A s s o c i a t i o n and th e A m phiodia A s s o c i a t i o n (S haded w i t h o u t L i n e s ) a t Hueneme Subm arine Canyon. ( F i g u r e 2, B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). APPENDIX FIGURE D-7 A Map Showing th e D i s t r i b u t i o n o f th e A m phiodia A s s o c i a t i o n on t h e S a n ta M onica Bay S h e l f and th e P a l o s V erdes S h e l f . ( F i g u r e 3, B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). 520 521 P T D U M E SANTA MONICA 3 4 ° 0 0' * * > • REDONOO BEACH F ig u r e D-6 F ig u r e D-7 APPENDIX FIGURE D-8 V e r t i c a l l y L in e d A r e a s I l l u s t r a t e th e D i s t r i b u t i o n o f th e Am phioplua h e x a c a n th u s A s s o c i a t i o n on th e San P e d ro Bay S h e l f ; t h e A m phiodia A s s o c i a t i o n i s Shown a s Shaded A re a s . ( F ig u r e 4, B a rn a rd and Z i e s e n h e n n e , 1 9 6 1 ). APPENDIX FIGURE D-9 D i s t r i b u t i o n o f t h e A m phiodia A s s o c i a t i o n on th e San D iego S h e l f ( F ig u r e 5, B a rn a rd and Z ie s e n h e n n e , 1 9 6 1 ). 522 523 LONG BEACH NEWPORT B E A C H ^4 U AjUN A BE ACH F i g u r e D-8 ^ • g L A J O L L A ill SA N DIEGO F ig u r e D-9 524 th e s h a l l o w - s h e l f b e n t h o s and th e d e e p - w a te r b e n t h o s , th u s fo rm in g a r o u g h ly b a n d e d p a t t e r n o f a n im a l a g g r e g a t i o n s . T h is b a n d in g i s d e m o n s tr a te d i n a map o f s t a n d i n g c ro p (A ppendix F i g u r e D - 1 0 ) . The d i s t r i b u t i o n o f m o llu s c a n wet w e ig h t (m ethod o f T h o rs o n , 1957; p. 492) i n g r a m s /s q u a re m e te r i s i l l u s t r a t e d by c o n to u r i n t e r v a l s o f 20, 40 and 400 gram s. T h e re i s a r i d g e - l i k e c o n c e n t r a t i o n o f h i g h v a l u e s a lo n g t h e l e n g t h o f t h e e a s t e r n 3 /4 o f t h e s h e l f . T h is i s th e r e s u l t o f th e h e a v y w e ig h ts o f C a r d i t a v e n t r i c o s a (B a rn a rd and Z ie s e n h e n n e , 1961; G. J o n e s , 1 9 6 4 ). The A m p h io d ia- C a r d i t a f a u n a a l s o e x te n d s a c r o s s th e S a n ta B a r b a r a s h e l f , b u t s t a n d i n g c ro p v a l u e s a r e low , l e s s th a n 40 g r a m s /s q u a r e m e te r o v e r m ost o f t h e a s s o c i a t i o n . S o u th o f Hueneme su b m a rin e canyon t h e A m p h io d ia- C a r d i t a a s s o c i a t i o n i s no l o n g e r a p a r t o f th e s h e l f b i o t a . (G. J o n e s , 1 9 6 4 ). The a n a l y s i s o f 30 OPB sa m p le s c o l l e c t e d fro m th e 9 - s t a t i o n g r i d o f f S a n t a B a r b a r a p r o v id e d i n f o r m a t i o n on i n t r a - a s s o c i a t i o n v a r i a t i o n an d p o p u l a t i o n d e n s i t y o f th e " d o m i n a n t s ,” i n th e A m p h io d ia - C a r d i t a a s s o c i a t i o n . G rid sam ple v o lu m es v a r i e d from 1 2 .4 to 7 6 .5 l i t e r s . The r e l a t i o n s h i p o f sam ple volume t o e a c h o f th e b i o l o g i c a l p a r a m e te r s i n v e s t i g a t e d was a n a ly z e d ; c o e f f i c i e n t s o f c o r r e l a t i o n ( r ) w ere c a l c u l a t e d from e a c h v a r i a b l e w ith sam p le v o lu m e. The r v a l u e s f o r th e e i g h t p a r a m e t e r s un d er c o n s i d e r a t i o n ra n g e d from - 0 .0 0 2 t o + 0 .2 5 1 (p 0 .0 5 ) . APPENDIX FIGURE D -10 A Map Showing th e D i s t r i b u t i o n o f M o llu s c a n S ta n d in g Crop on t h e P o i n t C o n c e p tio n S h e l f (A rea I ) ; C o n to u r I n t e r v a l s a r e 10, 50, 2 0 0 , 500, and 1000 Grams p e r S q u are M eter ( F ig u r e 24, B a rn a rd [ a ] , i n S te v e n s o n , 1951; F i g u r e 2, G. J o n e s , 1 9 6 4 ). 525 40' N v SANTA BARBARA tTATUTC MlkCI PT. ARGUELLO TO SANTA BARBARA MOLLUSK STANDING C R O P g / m 2 F ig u re D-10 526 527 D i r e c t u se o f t h e g r i d d a t a , w i t h o u t w e i g h t i n g i t to a c c o u n t f o r sam p le volum e i s j u s t i f i e d (G. J o n e s , 1 9 6 4 ), A t o t a l o f 1 ,2 8 6 sp e c im e n s o f C a r d i t a v e n t r i c o s a w ere c o l l e c t e d i n t h e s e s a m p le s . The mean was 144 s p e c i mens p e r s q u a r e m e te r ( r a n g e : 0 t o 2 6 8 ) , The means f o r e a c h o f 4 s e a s o n a l g ro u p s o f 9 g r i d sa m p le s a r e f a i r l y con s i s t e n t : 124 t o 156 p e r s q u a re m e te r . H ow ever, v a r i a t i o n w i t h i n e a c h g ro u p o f sam p les i s s u b s t a n t i a l . C a r d i t a c o m p ris e s h a l f o f th e t o t a l s t a n d i n g c ro p o f t h e a s s o c i a t i o n , The mean s t a n d i n g c ro p v a l u e s f o r t h i s s p e c i e s f o r e a c h o f th e 4 s e a s o n a l g ro u p s o f sam p les ra n g e from 5 0 . 8 t o 6 1 .6 grams p e r s q u a r e m e te r , o r 4 5 -6 4 p e r c e n t o f t h e t o t a l s t a n d i n g c ro p (G. J o n e s , 1 9 6 4 ). A m phiodia u r t i c a , th e o t h e r a s s o c i a t i o n ’'d o m in a n t, n a v e r a g e d 144 sp e c im e n s p e r s q u a r e m e te r ( r a n g e : 1 2 - 2 3 2 ). The December mean i s h i g h e s t (172) and t h e J u n e mean lo w e s t (96 ). O p h iu ro id s t a n d i n g c ro p ( p r i n c i p a l l y A. u r t i c a ) v a r i e d from 0 .8 t o 1 6 .8 grams p e r s q u a re m e te r w ith a n a n n u a l mean o f 7 .2 gram s p e r s q u a r e m e te r (G. J o n e s , 1 9 6 4 ). The g a s tr o p o d B i t t i u m r . s u b p la n a tu m i s p r o m in e n t i n sam p les c o l l e c t e d from th e A m p h io d ia- C a r d i t a a s s o c i a t i o n . The p o p u l a t i o n d e n s i t y o f B i t t i u m i n t h e g r i d sam p les r a n g e s from 0 to 344, w i t h a mean o f 100 p e r s q u a r e m e t e r . I t was c o l l e c t e d i n low num bers i n S ep tem b er (mean o f 4 p e r s q u a r e m e te r) when i t was a b s e n t from 4 o f 9 s a m p le s ; th e m eans f o r t h e o t h e r 3 s e a s o n a l g ro u p s a r e 120, 140 and 132 ; 528 p e r s q u a r e m e te r r e s p e c t i v e l y (G. J o n e s , 1964; B a r n a r d and Z i e s e n h e n n e , 1 9 6 1 ). O th e r n u m e r i c a l l y i m p o r t a n t s p e c i e s o f t h e A m p h io d ia - C a r d i t a a s s o c i a t i o n i n c l u d e t h e p e le c y p o d s P s e p h i d i a l o r d i (m ean, 172 p e r s q u a r e m e t e r ) , A x in o p s id a s e r r i c a t a (mean, 136/m 3 ) , N u c u la t e n u i s (97./m2 ) , A d o n to r - h i n a c y c l i a (52,/m2 ) , A c i l a c a s t r e n s i s (48,/m2 ) , an d M y s e lla s p p . (36,/mH) ; and t h e p o l y c h a e t e s P e c t i n a r i a c a l i f o r n l e n s i s ( 68./m2 ) , C h l o e i a p i n n a t a ( 68,/m2 ) , P r i o n o s p i o p i n n a t a (40,/m8) , G l y c e r a ca, i t a t a (36,/m2 ) , P r i o n o s p i o m alm g ren i (28./m3) , A r i c i d e a -.pp. (26,/m3) , S t e r n a s p i s f o s s o r (24,/m3) , and T e r e b e l l i d e s s t r o e m i (20./m2) ( B a r n a rd and Z i e s e n h e n n e , 1 961, T a b le 9 ) . A p i c t o r i a l r e p r e s e n t a t i o n o f a t y p i c a l 0 .2 5 nf3 p l o t fro m t h e A m p h io d ia - C a r d i t a com m unity i s shown i n A p p e n d ix F ig u r e D - l l ( F i g u r e 6 , B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). A s p e c i a l a n a l y s i s d e s ig n e d t o a s c e r t a i n t h e t y p e s o f s t a t i s t i c a l v a r i a b i l i t y e x p r e s s e d b y t h e A m p h io d ia - C a r d i t a g r i d d a t a (G. J o n e s Cb], i n S t e v e n s o n , 1961) was u n d e r t a k e n i n th e p r e p a r a t i o n o f th e r e v i s i o n o f t h e f i n a l r e p o r t o f t h e A l l a n H ancock F o u n d a tio n S u rv e y o f t h e m a in l a n d s h e l f (AHF:USC, 1 9 6 5 ). T h i s a n a l y s i s , and a s i m i l a r a n a l y s i s made f o r t h e L i s t r i o l o b u s com m unity g r i d , was made by Pom eroy ( p e r . comm ) . The n i n e s t a t i o n s a m p lin g g r i d was ex am in ed b o t h f o r s p a t i a l and te m p o r a l v a r i a t i o n . The APPENDIX FIGURE D - l l A P i c t o r i a l R e p r e s e n t a t i o n o f t h e A m p h io d ia - C a r d i t a A s s o c i a t i o n on t h e S a n ta B a r b a r a S h e l f W est o f Hueneme S u b m arin e Canyon. The P l o t R e p r e s e n t s a n A v e ra g e One- Q u a r t e r S q u are M e te r A r e a , B ased on 40 S a m p le s. O nly t h e "D o m in an t1 ’ and C o n s p ic u o u s ly L a rg e O rg a n ism s a r e Drawn. (The s m a l l o p h i u r o i d i s A m phiodia u r t i c a ; t h e p e l e c y p o d . The l a r g e p u p a - l i k e worm i s T r a v i s i a p u p a . The cone worm i s P e c t i n a r i a c a l i f o r n i e n s i s . T he s m a l l s n a i l i s B i t t i u m £ . s u b p la n a tu m . The g l o b u l a r worm I s S t e r n a s p i s f o s s o r . ( F i g u r e 6 , B a r n a r d and Z i e s e n h e n n e , 1 9 6 1 ). 529 530 F ig u r e D - l l 531 o b s e r v e d d i s t r i b u t i o n o f t h e num ber o f s p e c im e n s o f s i x s p e c i e s i n t h i s com m unity was com pared w i t h t h e d i s t r i b u t i o n t o be e x p e c t e d i f t h e v a r i a b i l i t y was c o m p l e t e l y r a n dom. F i n d i n g s v a r i e d by s p e c i e s . E x am p les o f a p p a r e n t random d i s t r i b u t i o n , o f s e a s o n a l v a r i a t i o n an d s p a t i a l v a r i a t i o n ( d e s i g n a t e d ,T s p o t t i n e s s " by Pom eroy) w ere o b s e r v e d . Random d i s t r i b u t i o n c h a r a c t e r i z e d T r a v i s i a pupa and S t e r n a s p i s f o s s o r ; s e a s o n a l v a r i a t i o n a p p e a r e d f o r B i t t i u m r . s u b p l a n a t u m , a n e x tre m e c a s e , and A m phiodia u r t i c a ; s p a t i a l v a r i a t i o n o r " s p o t t i n e s s ” c h a r a c t e r i z e d t h e d i s t r i b u t i o n o f C a r d i t a v e n t r i c o s a , B i t t i u m r . s u b p la n a tu m , A m phiodia u r t i c a and P e c t i n a r i a c a l i f o r n i e n s i s . L i t t l e k n o w led g e e x i s t s c o n c e r n i n g t h e d e t a i l s o f t h e b i o l o g y o f m ost o f t h e b e n t h i c i n v e r t e b r a t e a n im a ls t h a t i n h a b i t t h e m a in la n d s h e l f . H ow ever, r e p r o d u c t i o n i n th e p e le c y p o d C a r d i t a v e n t r i c o s a h a s b e e n s t u d i e d by G. J o n e s (1 9 6 4 ). C a r d i t a l a c k s a p e l a g i c l a r v a l s t a g e and i n s t e a d b r o o d s i t s young i n p o u c h e s i n t h e c t e n i d i a (G. J o n e s , 1 9 6 3 ). T h is mode o f d e v e lo p m e n t p l u s t h e e x t e n s i o n o f m a t e r n a l c a r e b e y o n d th e p e r i o d o f b ro o d p r o t e c t i o n may p a r t l y e x p l a i n th e p a r t i c u l a r l y " s p o t t y " d i s t r i b u t i o n o f s p e c im e n s o f t h i s s p e c i e s o b s e r v e d i n t h e g r i d s a m p le s . 532 The A m phiodia A s s o c i a t i o n S o u th o f th e Hueneme su b m a rin e canyon t h e A m phiodia u r t i c a a s s o c i a t i o n o c c u r s g e n e r a l l y on th e o u t e r p o r t i o n (60 t o 90 m e te r s ) o f t h e s o u t h e r n s h e l f a lo n g i t s e n t i r e l e n g t h . I t p o p u l a t e s 432 km (=130 s q . m i l e s ) o r 21 p e r c e n t o f t h e s h e l f b o tto m . The e x t e n t o f i t s d ev elo p m en t i s v a r i a b l e , and i t s d i s t r i b u t i o n i s d i s c o n t i n u o u s (A ppen d i x P i g u r e D-5 D-7 and D -9 ). I t i s r e d u c e d o r m i s s i n g i n a r e a s o f s u b s t r a t e c o m p le x ity su c h a s t h e c e n t r a l s h e l f p r o j e c t i o n i n S a n ta M onica Bay, t h e P a lo s V e rd e s S h e l f , t h e San P e d ro S h e l f and th e s o u t h e r n p o r t i o n o f th e San D ieg o S h e l f (B a r n a rd and Z ie s e n h e n n e , 1 9 6 1 ). S e d im e n ts from 34 r e p r e s e n t a t i v e s a m p le s w i t h i n t h i s a s s o c i a t i o n w ere s i l t y s a n d s and san d y s i l t s w ith an a v e r a g e m ed ian d ia m e te r o f 0 .0 4 9 mm. ( r a n g e , 0 . 0 2 8 - 0 .0 8 1 mm) and a mean p e r c e n t sa n d o f 1 9 .2 ( r a n g e , 2 . 0 - 6 4 . 0 p e r c e n t ) . The mean number o f s p e c i e s / s a m p l e , 8 3 , and t h e mean num ber o f sp ecim e n s/m 2 , 3 513, r e p o r t e d f o r t h i s a s s o c i a t i o n , b a s e d on 8 r e p r e s e n t a t i v e s a m p le s , a r e a lm o s t i d e n t i c a l t o t h e v a l u e s f o r t h e s e two p a r a m e t e r s f o r t h e A m p h io d ia- C a r d i t a a s s o c i a t i o n (B a rn a rd and Z ie s e n h e n n e , 1 9 6 1 ). The mean s t a n d i n g c ro p i n th e A m phiodia a s s o c i a t i o n i s 255 g,/m8 ( B a r n a r d , [a ] i n S te v e n s o n , 1961) and th e mean p o p u l a t i o n d e n s i t y i s 1516,/m 2 ; t h e l a t t e r f i g u r e r e p r e s e n t s a s u b - . s t a n t i a l i n c r e a s e fro m th e 408/m 2 f o r t h e A m p h io d ia- C a r d i t a a s s o c i a t i o n ( B a r n a r d and Z i e s e n h e n n e , 1 9 6 1 , T a b le 9 ) . A p a r t o f t h i s o b s e r v e d d i f f e r e n c e i n d e n s i t y i s no d o u b t due t o t h e a b s e n c e o f C a r d i t a i n t h e a s s o c i a t i o n . H ow ever, t h e o b s e r v e d d i f f e r e n c e i n s e d im e n t c h a r a c t e r , a s e v i d e n c e d by a s h i f t i n mean p e r c e n t sa n d fro m 37 ( i n t h e A m p h io d ia - C a r d i t a a s s o c i a t i o n ) t o 19 p e r c e n t , may b e an i m p o r t a n t f a c t o r . By c o m b in in g s a m p le s fro m t h r e e a s s o c i a t i o n s , A m p h io d ia , A m p h io d ia - O n u p h is , an d O n u p h is , B a r n a r d and Z i e s e n h e n n e (1 9 6 1 ; T a b le 12) h a v e shown t h a t A m phiodia u r t i c a p o p u l a t i o n d e n s i t y i s h i g h e s t w h ere th e p r o p o r t i o n o f s a n d i s l o w e s t . F o r 0 -2 9 p e r c e n t s a n d (29 s a m p l e s ) , t h e mean p o p u l a t i o n d e n s i t y o f A m phiodia u r t i c a was 1256,/m3 ; f o r 3 0 -5 9 p e r c e n t s a n d (12 s a m p l e s ) , t h e mean was 564,/m2 ; and f o r 6 0 -1 0 0 p e r c e n t s a n d (9 s a m p l e s ) , th e mean was 256,/m2 . Many o f t h e n u m e r i c a l l y i m p o r t a n t s p e c i e s o f th e A m p h io d ia -C a r d i t a a s s o c i a t i o n a r e a l s o t h e i m p o r t a n t s p e c i e s i n t h e A m phiodia a s s o c i a t i o n . T h e s e i n c l u d e th e p e l e c y p o d s A x in o p s id a s e r r i c a t a (m ean, 57,/m2 ) , and My.se 11 a s p p . (2 6 /m 3) ; and t h e p o l y c h a e t e s P e c t i n a r i a c a l i f o r n i e n s i s (92./ms ) , A r i c i d e a sp p . (42/m 2 ) , C h l o e i a p i n n a t a (27,/ms ) , T e r e b e l l i d e s s t r o e m i (22,/m2 ) , G ly c e r a c a p i t a t a (19./m2 ) , an d P r i o n o s p i o p i n n a t a (13/m 2 ) . The o p h i u r o i d A m p h ip h o lis s q u a m a t a , t h a t o c c u r r e d a t t h e low p o p u l a t i o n d e n s i t y o f i 8,/m2 i n t h e A m p h i o d i a - C a r d it a a s s o c i a t i o n , d e m o n s tr a te d a 534 m arked i n c r e a s e i n d e n s i t y T mean 73./m3 , i n t h e A m phiodia a s s o c i a t i o n a p i c t o r i a l r e p r e s e n t a t i o n o f a t y p i c a l 0 .2 5 m3 p l o t fro m th e A m phiodia a s s o c i a t i o n i s shown i n A p p e n d ix F i g u r e D-12 ( F i g u r e 7, B a rn a rd and Z i e s e n h e n n e , 1 9 6 1 ). The A m p h io d ia -O n u p h is and O n u p h is A s s o c i a t i o n s B a r n a r d and Z ie s e n h e n n e (1961) d e s c r i b e two m o d i f i c a t i o n s o f t h e A m phiodia a s s o c i a t i o n b a s e d on two r e p r e s e n t a t i v e s e t s o f s a m p le s . S am ples i n one g ro u p were " d o m in a te d ” by A m phiodia and t h e t u b e - b u i l d i n g p o l y c h a e t e O nuphis n e b u l o s a and o t h e r s p e c i e s o f t h i s g e n u s . I n th e o t h e r sam ple g ro u p O n uphis a l o n e was " d o m in a n t" . The f i r s t o f t h e s e two a s s o c i a t i o n s may be r e g a r d e d as a d i s t i n c t s u b - a s s o c i a t i o n ; b u t th e o t h e r p r o b a b l y r e p r e s e n t s an " e c o t o n e , " a n a r e a o f r a p i d f a u n a l ch an g e b e tw e e n a d j a c e n t a s s o c i a t i o n s . The A m p h io d ia - O nuphis s u b - a s s o c i a t i o n o c c u r s i n d e p th s o f fro m a b o u t 40 t o 70 m e t e r s on s e d im e n t s t h a t a r e on t h e a v e r a g e somew hat c o a r s e r t h a n t h o s e i n e i t h e r th e A m p h io d ia -C a r d i t a o r t h e A m phiodia a s s o c i a t i o n s . B a r n a r d and Z ie s e n h e n n e (1961) e s t i m a t e t h a t t h i s s u b - a s s o c i a t i o n p o p u l a t e s 2 p e r c e n t o f th e s h e l f . S e d im e n ts i n 12 r e p r e s e n t a t i v e s a m p le s w i t h i n t h i s a s s o c i a t i o n had a mean m ed ian d i a m e t e r o f 0 .0 8 7 mm ( r a n g e , 0 . 0 2 2 - 0 . 2 4 1 mm). The mean p e r c e n t a g e o f san d f o r chese s a m p le s was 51 p e r c e n t APPENDIX FIGURE D-12 A P i c t o r i a l R e p r e s e n t a t i o n o f th e A m phiodia u r t l c a A s s o c i a t i o n on th e M ain la n d S h e l f S o u t h e a s t o f Hueneme S ubm arine C anyon. The P l o t R e p r e s e n t s an A v erag e O n e -Q u a rte r S q u a re M eter A re a , B ased on 40 s a m p le s . O nly th e "Dominant™ and C o n s p ic u o u s ly L a rg e O rganism s a r e Drawn. (The s m a l l o p h i u r o i d i s A m phiodia u r t i c a ; th e l a r g e o p h i u r o i d i s A m phiura a r c y s t a t a . The p u p a - l i k e worm i s T r a v i s i a p u p a . The cone worm i s P e c t i n a r i a c a l i f o r n i e n s i s . The g l o b u l a r worm i s S t e r n a s p l s f o s s o r . ( F ig u r e 7 , B a rn a rd and Z ie s e n h e n n e , 1 9 6 1 ). 535 536 Figure D-12 537 ( r a n g e , 1 1 -8 1 p e r c e n t ) ; t h i s v a l u e i s c o n s i d e r a b l y h i g h e r th a n t h a t i n th e A m phiodia a s s o c i a t i o n . F iv e sam p les had a mean number o f s p e c i e s / s a m p l e o f 117 and a mean number o f s p e c im e n s/m 2 o f 3672 (B a rn a rd and Z ie s e n h e n n e , 1 9 6 1 ). The mean s t a n d i n g c ro p i n t h i s s u b - a s s o c i a t i o n i s 182 g/m3 (B a r n a rd , [ a ] i n S te v e n s o n , 1 9 6 1 ). The p o p u l a t i o n d e n s i t y o f th e "d o m in a n t" o p h iu r o id A m phiodia u r t i c a (mean specimens,/m s = 252) was low er th a n i n e i t h e r t h e A m phiodia o r A m p h io d ia- C a r d i t a a s s o c i a t i o n s . O nuphis s p p . , th e o t h e r " d o m in a n t" , a v e ra g e d 104 i n d i v i d u a l s / m 8 . The l i s t o f s p e c i e s i m p o r t a n t i n t h i s a s s o c i a t i o n i s v e r y s i m i l a r t o th o s e f o r t h e c l o s e l y r e l a t e d o p h i u r o i d a s s o c i a t i o n s p r e v i o u s l y d e s c r i b e d . E x c e p tin g th e " d o m in a n t" O n u p h is , th e p o l y c h a e t e s p e c i e s l i s t e d a r e th e same and o n ly th e n u m e r ic a l r a n k o r d e r i s d i f f e r e n t f o r th e A m phiodia and A m p h io d ia-C a r d i t a a s s o c i a t i o n s . T h e i r o r d e r h e r e i s a s f o l l o w s : P r i o n o s p i o m alm g ren i (mean, 104/m2) , A r i c i d e a s p p . (66/V3) , P r i o n o s p i o p i n n a t a (56,/m2) , P e c t i n a r i a c a l i f o r n i e n s i s (53/m 2) , G ly c e ra c a p i t a t a (44,/m2 ) , S t e r n a s p i s f o s s o r (37,/m2) , C h l o e i a p i n n a t a (mean, 29./m2 ) , and T e r e b e l l i d e s s t r o e m i (22,/m?3) . The p ro m in e n t m o llu s c a n e le m e n ts i n c l u d e A x in o p s id a s e r r i c a t a (mean, 136,/m2 ) , B i t t l u m r . s u b p l ana turn (mean, 50/m2 ) , and N ucu la t e n u i s (m ean, 30,/m2 ) . B a r n a r d and Z ie s e n h e n n e (1961) b a s e t h e i r d e s c r i p t i o n s o f t h e O nuphis " e c o to n e " on b u t f o u r sam p les , 538 c o l l e c t e d o v e r a wide d e p t h r a n g e T 15 t o 145 m e t e r s . B a r n a r d ( [ a ] , i n S t e v e n s o n , 1961) c o n s i d e r s t h i s ,T e c o t o n e M t o b e e x t e n s i v e l y d i s t r i b u t e d on t h e s h e l f , p o p u l a t i n g 3 p e r c e n t o f t h e b o tto m . S e d im e n ts a t t h e s e f o u r l o c a t i o n s w ere c o n s i d e r a b l y c o a r s e r th a n t h o s e w i t h i n t h e A m phiodia and A m p h io d ia - r e l a t e d a s s o c i a t i o n s . The mean m ed ian d iam e t e r o f th e b o tto m s e d im e n ts w h e re t h e s e s a m p le s w ere c o l l e c t e d was 0 .1 5 3 mm ( r a n g e , 0 . 0 5 6 - 0 . 2 4 1 mm); p e r c e n t a g e o f s a n d a v e r a g e d 7 5 .8 ( r a n g e , 2 5 . 0 - 9 8 . 0 p e r c e n t ) . The mean num ber o f s p e c i e s / s a m p l e , 78, an d s p e c im e n s /m 2, 1951, a v e r a g e d l e s s th a n i n t h e r e l a t e d o p h i u r o i d a s s o c i a t i o n s . The mean s t a n d i n g c ro p w as 159 g / m 2 ( B a r n a r d , [al i n S t e v e n s o n , 1 9 6 1 ). Of th e s p e c i e s i m p o r t a n t i n t h e o t h e r a s s o c i a t i o n s , o n ly t h e " d o m in a n t" o r g a n is m , t h e p o l y c h a e t e O nuphis s p p . , had a h i g h mean p o p u l a t i o n d e n s i t y , 2 0 5 /m 3. The o t h e r i m p o r t a n t s p e c i e s ra n k e d a s f o l l o w s : P r i o n o s p i o m a lm g re n i (m ean, 3 7 /m 2) , A m phiodia u r t i c a (2 4 /m 3) , A r i c i d e a s p p . (14./m2) , P r i o n o s p i o p i n n a t a (13,/m2) , G ly c e r a c a p i t a t a ( 8/ m 3) , P i s t a s p . (7,/m3) , T e r e b e l l i d e s s t r o e m i (7./m3) , P e c t i n a r i a c a l i f o r n i e n s i s (4,/m2) , C h l o e i a p i n n a t a (3,/m2) , and A x in o p s id a s e r r i c a t a (3,/m2) ; o c c u r r i n g a t d e n s i t i e s o f l e s s th a n 3,/m2 w ere C a r d l t a v e n t r i c o s a , N u c u la t e n u i s , B i t t i u m s u b p la n a tu m , S t e r n a s p i s f o s s o r , A c i l a c a s t r e n s i s , P s e p h i d i a l o r d i , M y s e lla s p p . , an d A d o n to r h in a c y c l i a . 539 The A m phioplus H e x a c a n th u s A s s o c i a t i o n T h is a s s o c i a t i o n may a l s o be a m o d i f i c a t i o n o f t h e A m ph io d ia a s s o c i a t i o n , b u t B a r n a r d and Z i e s e n h e n n e (1 9 6 1 ) c o n s i d e r i t d i s t i n c t . The A m phioplus h e x a c a n th u s a s s o c i a t i o n p o p u l a t e s a b o u t 6G kms (18 s q u a r e m i l e s ) o f f i n e s a n d b o tto m a t d e p t h s b e tw e e n 13 and 55 m e t e r s . The maximum a r e a l d e v e lo p m e n t o c c u r s i n t h e San P e d ro s h e l f , b u t s m a l l e r p a t c h e s a r e r e p o r t e d on t h e S a n t a M onica and O c e a n s id e s h e l v e s , (A p p e n d ix F i g u r e D-8) . B a r n a r d ( [ a ] , i n S t e v e n s o n , 196JL) e s t i m a t e s t h a t t h i s a s s o c i a t i o n p o p u l a t e s 6 p e r c e n t o f t h e a r e a o f th e m a in la n d s h e l f , The a s s o c i a t i o n i s a l s o an i m p o r t a n t f e a t u r e o f t h e M o n te re y Bay s h e l f b i o t a . B a r n a r d and Z ie s e n h e n n e (1961) comment on th e g e o g r a p h i c d i s t r i b u t i o n o f t h i s a s s o c i a t i o n : . . . The com m unity i s w id e s p r e a d and d o m in a n t on t h e M o n terey Bay s h e l f s e v e r a l h u n d re d m i l e s t o th e n o r t h o f t h e a r e a u n d e r c o n s i d e r a t i o n . , and t h e r e a r e s e v e r a l i n t e r e s t i n g d i f f e r e n c e s . M ost o f t h e c o a s t a l s h e l f i n s o u t h e r n C a l i f o r n i a l i e s i n d e p th s o f 10 t o 35 f a th o m s , w i t h a s h a r p l y i n c r e a s e d g r a d i e n t and a s m a l l g e o g r a p h i c a r e a i n t h e 35 t o 50 f a th o m d e p t h s . I n M o n te re y Bay a l a r g e s h a r e o f th e s h e l f l i e s i n d e p th s o f 30 t o 50 f a th o m s , and i s bounded on b o t h s i d e s by i n c r e a s e d g r a d i e n t s (U. S . C. G. S. C h a r t 5 4 0 3 ) . As a r e s u l t , f i n e s a n d s a r e d e p o s i t e d on t h e f l a t o f t h e s h e l f a t g r e a t e r d e p th s i n M o n te re y Bay t h a n i n s o u t h e r n C a l i f o r n i a . E x c e p t on th e San P e d r o s h e l f , l a r g e a r e a s o f s i m i l a r s a n d y e n v ir o n m e n t i n d e p t h s o f 35 t o 50 fa th o m s a r e a b s e n t i n s o u t h e r n C a l i f o r n i a , and t h i s may a c c o u n t f o r t h e p a u c i t y o f t h e A. h e x a c a n t h u s com m unity. A n o th e r m echanism must""be— o p e r a f i v e , h o w e v e r, i n t h a t (1) t h e A. h e x a c a n t h u s b o tto m s i n s o u t h e r p C a l i f o r n i a a r e s h a l l o w e r th a n a t M o n te re y and th u s a r e i n warm er 540' w a t e r s ; and ( 2 ) t h e a n a l y s e s o f s e d im e n t p a r t i c l e s i z e a r e s c a r c e l y d i f f e r e n t t h a n . ythose o f t h e A. q r t i c a b o t t o m s , a l t h o u g h c o r r e l a t i o n w i t h s e d im e n t c h a r t s shows t h e A. h e x a c a n t h u s community o c c u p y i n g f i n e s a n d s and t h e A. u r t i c a com m unity o c c u p y i n g s i l t y s a n d s and sa n d y s i l t s - (p p . 138) I n te rm s o f t h e s e d im e n t d a t a p r e s e n t e d , t h e e n v i ro n m e n ts o f t h e two a s s o c i a t i o n s a r e somew hat d i f f e r e n t . S ix r e p r e s e n t a t i v e s a m p le s fro m t h e A m phioplus h e x a c a n t h u s a s s o c i a t i o n h ad a mean m ed ian d i a m e t e r o f 0 .0 6 2 mm ( r a n g e , 0 .0 5 4 - 0 .0 7 1 mm) and a mean p e r c e n t a g e o f s a n d o f 4 8 .2 ( r a n g e , 3 1 -6 9 p e r c e n t ) a s com pared t o 0 .0 4 9 mm. a n d 1 9 .2 p e r c e n t r e s p e c t i v e l y f o r t h e s e same p a r a m e t e r s fro m t h e A m phiodia u r t i c a a s s o c i a t i o n . B a r n a r d and Z ie s e n h e n n e (1 9 6 1 , p . 1 3 8 -1 4 0 ) d e s c r i b e an a d d i t i o n a l d i f f e r e n c e I n t h e s e d im e n ts c h a r a c t e r i s t i c a l l y i n h a b i t e d by th e two a s s o c i a t i o n s . A c c o r d in g to t h e s e a u t h o r s , b a s e d on f i e l d o b s e r v a t i o n s , . . . The s e d im e n t s o f t h e A m p h io p lu s bed w ere c l a s s i f i e d as f i n e s a n d s w i t h l i t t l e f e e l i n g o f s t i c k i n e s s b u t w i t h a n o t i c e a b l e s h e a r s t r e n g t h and c o m p a c tn e s s . The s e d im e n t s fro m t h e A m phiodia b e d w ere c l a s s i f i e d a s sa n d y s i l t s o r s i l t y s a n d s , w i t h a s t i c k y and c o m p r e s s i b l e f e e l i n g . S in c e m o st muddy o p h l u r o l d s subm erge th e m s e lv e s s l i g h t l y i n t h e s e d im e n t s u r f a c e , t h e s m a l l s p e c i e s , A m p h io d ia u r t i c a , may b e a b l e t o subm erge i n t h e s i l t y s e d i - m e n ts , b u t i n our e s t i m a t i o n w ould b e u n a b l e t o do t h i s a s w e l l i n t h e com pact f i n e s a n d s o f t h e A m p h ioplus b e d s . The l a r g e r A m phioplus h e x a c a n t h u s may b e c o r r e l a t e d w i t h t h e h i g h e r sa n d p e r c e n t a g e s , b u t t h i s f a i l s t o t a k e i n t o a c c o u n t t h e f a c t t h a t t h e j u v e n i l e s o f A. h e x a c a n t h u s a r e a s s m a l l a s A. u r t i c a and t h a t A. u r t i c a e x i s t s a s t h e p r i n c i p a l s u b d o m in a n t i n t h e com m unity. I t I s p o s s i b l e t h a t j u v e n i l e s o f A. h e x a c a n t h u s and a d u l t s o f A. u r t i c a L 541 l i v e on s m a l l p a t c h e s o f f i n e r s e d i m e n t s m ix ed w i t h c o a r s e r m a t e r i a l s ; o u r s a m p le s and t e c h n i q u e s a r e n o t s u i t a b l e f o r i n v e s t i g a t i n g t h i s p o s s i b i l i t y . m • • S ev en r e p r e s e n t a t i v e s a m p le s a v e r a g e d 106 s p e c i e s / sam p le and 3345 s p e c i m e n s / m 2. The mean s t a n d i n g c ro p i n t h i s a s s o c i a t i o n a v e r a g e s 159 g/m 2 ( B a r n a r d [ a ] , i n S t e v e n s o n , 1961)* The " d o m in a n t" o p h i u r o i d A m p h io p lu s h e x a c a n t h u s had a mean p o p u l a t i o n d e n s i t y o f 120,/m3. I n s p i t e o f t h e r e l a t i v e l y h i g h p o p u l a t i o n d e n s i t y o f A m ph io d ia u r t i c a i n t h i s a s s o c i a t i o n 1 9 1 /m 2 , B a r n a r d and Z ie s e n h e n n e (1961) c h o s e t o d e s c r i b e t h e A m phioplus h e x a c a n t h u s a s s o c i a t i o n a s a d i s t i n c t f a u n a l a s s o c i a t i o n r a t h e r t h a n a f a c i e s o f t h e A m phiodia u r t i c a a s s o c i a t i o n . The i n a r t i c u l a t e b r a c h i o p o d G l o t t i d i a a l b i d a i s a n i m p o r t a n t f a u n a l e l e m e n t i n t h i s a s s o c i a t i o n * I t s d i s t r i b u t i o n and a b u n d an ce on t h e m a in la n d s h e l f - h a v e b e e n d e s c r i b e d by J o n e s and B a r n a r d ( 1 9 6 3 ). . . . . G l o t t i d i a a l b i d a o c c u r s a lo n g t h e f u l l l e n g t h o f t h e m a in la n d s h e l f o f s o u t h e r n C a l i f o r n i a , b u t i t s d i s t r i b u t i o n i s n o t c o n t i n u o u s ; a r e a s o f h i g h p o p u l a t i o n d e n s i t y a r e s e p a r a t e d by a r e a s o f low d e n s i t y o r a r e a s a p p a r e n t l y d e v o id o f t h i s s p e c i e s . G e n e r a l l y , G l o t t i d i a i s more w i d e l y d i s t r i b u t e d and more a b u n d a n t on t h e n o r t h e r n and c e n t r a l p o r t i o n s o f t h e s h e l f ( n o r t h o f N ew p o rt, C a l i f o r n i a ) . ( p . 35) The l a r g e s t and d e n s e s t a r e a o f G l o t t i d i a , o v e r 500 p e r s q u a r e m e t e r , i s on t h e b r o a d s h e l f o f San P e d r o B ay. I t s g e o g r a p h ic l o c a t i o n c o i n c i d e s w i t h t h e l o c a t i o n o f t h e A m p h io p lu s h e x a c a n t h u s community ( F i g u r e 4 , B a r n a r d a n d Z i e s e n - henrie 1 9 6 1 ). (p* 36) G l o t t i d i a i s tw ic e a s a b u n d a n t on t h e m a in la n d s h e l f a s A m p h io p lu s, a v e r a g i n g 5 . 6 sp e c im e n s p e r sam p le i n c o n t r a s t to 2 .8 i n t h e 176 s a m p le s . G l o t t i d i a o c c u r r e d in 80 a n d A m phioplus i n 54 o f t h e 176 s a m p le s . B oth s p e c i e s o c c u r r e d t o g e t h e r i n 42 o f t h e s a m p le s , so t h a t G l o t t i d i a was a s s o c i a t e d w i t h 78% o f th e p o s i t i v e A m phioplus s a m p le s b u t A m phioplus o c c u r r e d i n o n ly 53% o f th e p o s i t i v e G l o t t i d i a sam p'les. B ased on t h e s e d a ta t h e amount o f a s s o c i a t i o n was t e s t e d by th e m ethod o f D ice (1 9 4 5 ); t h e r e s u l t i n g c h i - s q u a r e d v a lu e o f 4 4 .5 i s f a r above t h a t f o r th e o n e - p e r c e n t l e v e l o f s i g n i f i c a n c e ( 6 .6 3 5 , 1 d . f . ) i n d i c a t i n g t h a t t h e ob s e r v e d a s s o c i a t i o n o f t h e s e two s p e c i e s i s n o t due t o random s a m p lin g e r r o r s . The a s s o c i a t i o n o f G l o t t i d i a and A m phioplus i s a l s o s t r i k i n g when r e c k o n in g t o t a l number o f s p e c im e n s , f o r t h e 42 s a m p le s i n w hich b o th w ere c o l l e c t e d c o n t a i n e d 82% o f th e G l o t t i d i a and 89% o f th e A m phioplus s p e c im e n s. H e n c e , o n ly 18% o f th e G l o t t i d i a " and ll% o f th e A m phioplus sp e c im e n s were c o l l e c t e d o u t s i d e th e a r e a s o f common o c c u r r e n c e . (p . 43) M ost o f th e o t h e r n u m e r i c a l l y i m p o r t a n t s p e c i e s o f t h i s a s s o c i a t i o n a r e th o s e w h ic h a r e i m p o r t a n t i n t h e o t h e r o p h i u r o i d a s s o c i a t i o n s . I n c lu d e d a r e t h e f o l l o w i n g : P r i o n o s p i o p i n n a t a (mean, 210,/m3) , P r i o n o s p i o m alm g ren j (155,/m2) , A r i c i d e a s p p . (125./m2) , A x in o p s id a s e r r i c a t a (6 9 /m 2) , O nuphis sp p . (29,/m2) , C h l o e i a p i n n a t a (2 5 /m 2) , P e c t i n a r l a c a l i f o r n i e n s l s (21./m2) , M y s e lla s p p . (18,/m2) , A m p h ip h o lis squam ata (17,/m3) , T h a le n e s s a s p l n o s a (1 5 /m s ) , S t e r n a s p l s f o s s o r ( 1 4 /m s ), P i s t a s p . (1 4 /m 2) , and G ly c e ra c a p i t a t a (1 3 /m 2) . A p i c t o r i a l r e p r e s e n t a t i o n o f a t y p i c a l 0 .2 5 m2 p l o t fro m t h e A m phioplus h e x a c a n th u s a s s o c i a t i o n i s shown i n A pp en d ix F i g u r e D-13 ( F ig u r e 8 , B a r n a r d and Z ie s e n h e n n e , 1961; F ig u r e 12, J o n e s an d B a rn a rd 1 9 6 3 ). APPENDIX FIGURE D-13 A P i c t o r i a l R e p r e s e n t a t i o n o f th e A m phioplus h e x a c a n th u s A s s o c i a t i o n on th e San P ed ro Bay S h e l f . The P l o t R e p r e s e n t s an A v erag e o n e - Q u a r te r S q u a re M e te r A rea, B a se d on 12 S am p les. Only t h e "D om inant1 * and C o n s p ic u o u s ly L a rg e O rganism s a r e Drawn. (The l a r g e o p h i u r o i d s a r e A m p h io p lu s h e x a c a n t h u s . The s m a l l o p h i u r o i d s a r e A m phiodia u r t i c a . The cone worm i s P e c t i n a r i a c a l i f o r n i e n s j s . The g l o b u l a r worm i s S t e r n a s p i s f o s s o r . The s m a ll s n a i l i s B i t t i u m s p . The p e d u n c u l a t e b r a c h io p o d i s G l o t t i d i a a l b i d a . The v e ry s m a l l worms w i t h a n t e r i o r p a l p s a r e P r i o n o s p i o s p p . [P r i o n o s p i o m alm g ren i and P r i o n o s p i o p i n n a t a ]) ( F i g u r e 8 , B a r n a r d and Z ie s e n h e n n e , 1 9 6 1 ). 543 Figure D-13 545 . The L i s t r i o l o b u s A s s o c i a t i o n I n s h o r e from t h e A m phiodia- C a r d i t a a s s o c i a t i o n , in th e l a r g e s i l t d e p o s i t o f th e S a n ta B a r b a r a s h e l f and in s i m i l a r s e d im e n ts on th e P o i n t C o n c e p tio n s h e l f , i s a unique a s s o c i a t i o n " d o m in a te d ” by th e e c h i u r o i d L i s t r i o l o b u s p e lo d e s (B a rn a rd and H artm an, 1 9 5 9 ). The mean d i a m e t e r o f s e d im e n ts p o p u la te d by t h i s a s s o c i a t i o n i s a b o u t 0 .0 2 9 mm. I t o c c u r s i n d e p th s o f from 30 t o 60 m e te r s w ith i t s g r e a t e s t d e v e lo p m e n t a lo n g t h e 37 m e te r c o n t o u r , w here t h e mean number o f L i s t r i o l o b u s i s 100/m2 , r e p r e s e n t i n g a s t a n d i n g c ro p o f a p p r o x im a te ly 1 ,000 g/m3 (w et w e i g h t ) . The maximum s ta n d i n g c ro p o b s e rv e d i n t h i s a s s o c i a t i o n e x c e e d e d 1,600 g/m2 . The s t a n d i n g c ro p o f L i s t r i o l o b u s p e lo d e s d i s t r i b u t i o n on th e S a n ta B a r b a r a s h e l f h a s b e e n mapped by B a rn a rd ( [ a ] , i n S te v e n s o n , 1961, F ig u re 3 3 ); t h i s f i g u r e i s r e p e a te d i n t h i s r e p o r t a s A ppen d ix F ig u re D -14. A c c o rd in g to B a rn a rd and H artm an (1959) th e L i s t r i o lo b u s a s s o c i a t i o n o f th e S a n ta B a rb a ra s h e l f c o v e r s a p a r t i a l l y d i s c o n t i n u o u s a r e a o f 46 s q u a r e n a u t i c a l m ile s ( 1 5 6 .3 km2 ) . The s m a l l e r s e c t o r o f t h i s a s s o c i a t i o n on th e P o in t C o n c e p tio n s h e l f i n h a b i t s a b o u t 20 s q u a re n a u t i c a l m i l e s ( 6 8 .4 km2 ) o f th e s h e l f b o tto m . A l t o g e t h e r 6 p e r c e n t o f t h e a r e a o f t h e m a in la n d s h e l f i s p o p u la te d by t h i s a s s o c i a t i o n (B a rn a rd [ a ] , i n S te v e n s o n , 1 9 6 1 ). The eastw ard e x p a n s io n o f t h i s f a u n a n a rro w s o f f V e n tu r a ; h e r e i t i s r e - ; j p la c e d by th e N o t h r i a - T e l l i n a a s s o c i a t i o n . S o u th o f t h i s APPENDIX FIGURE D-14 A Map Showing t h e D i s t r i b u t i o n o f L i s t r i o l o b u s p e l o d e s S t a n d i n g d r o p on t h e S a n ta B a r b a r a S h e l f (A re a I I ) ; C o n to u r I n t e r v a l s a r e 5 0 , 200, 500 and 1000 Grams p e r S q u a re M e te r ( F i g u r e 33, B a r n a r d [ a ] , i n S t e v e n s o n , 1961) 546 VENTURA -200- SANTA BARBARA TO POINT DUME L is trio lo b u s p e lo d e s Figure D-14 547 548 p o i n t t h e L i s t r i o l o b u s a s s o c i a t i o n d o e s n o t a p p e a r as a d i s t i n c t f a u n a l u n i t of t h e s h e l f b i o t a . B a rn a rd and H artm an (1 9 5 9 ; T a b le 1) have sum m arized f i v e r e p r e s e n t a t i v e sa m p le s from t h i s a s s o c i a t i o n . T hese sam p les had a mean number o f s p e c i e s / s a m p l e o f 80 and a mean number o f sp e c im e n s/m 2 o f 2330. The n u m e r i c a l l y im p o r t a n t s p e c i e s i n t h i s a s s o c i a t i o n i n c l u d e t h e f o l l o w i n g : A m phiodia u r t i c a (m ean, 98/m2 ) , S a x i c a v e l l a p a c i f i c a (93/m 3 ) , C e r a t o c e p h a l a c r o s s l a n d j a m e ric a n a (76/m 2 ) , C a l l i a n a s s a s p . (64/m 2 ) , H e sp ero n o e s p . (56/m 2 ) , P h o ro n o p - s i s s p . (48/m 2 ) , M arphysa s p . (40/m 2 ) , P e c t i n a r i a c a l i f o r n i - e n s i s (36/m 2 ) , P i n n i x a s p p . (30/m 2 ) , S t e r n a s p i s f o s s o r (16/m2 ) , and G ly c e r a c a p i t a t a (1 0 /m 2 ) . L a rg e s p e c i e s o c c u r r i n g a t low f r e q u e n c i e s i n c l u d e Compsomyax s u b d ia p h a n a , A s y c h is s p p . , P i s t a d i s . j u n c t a , S t y l a t u l a s p . , a c e r i a n t h i d anemone, and o t h e r s p e c i e s o f G l y c e r a . A p i c t o r i a l r e p r e s e n t a t i o n o f a t y p i c a l 0 .2 5 m2 p l o t from t h e L i s t r i o l o b u s a s s o c i a t i o n i s shown i n A ppen d ix F ig u r e D-15 ( F ig u r e 1, B a rn a rd and H artm an , 1 9 5 9 ). I n t r a - a s s o c i a t i o n v a r i a t i o n and p o p u l a t i o n d e n s i t y were i n v e s t i g a t e d i n t h e L i s t r i o l o b u s a s s o c i a t i o n by means o f a n i n e s t a t i o n g r i d s i m i l a r to t h a t u t i l i z e d i n th e A m phiodia- C a r d i t a a s s o c i a t i o n (G. J o n e s , 1964; T a b le 3 ) . Sample volum es w ere l e s s v a r i a b l e i n t h i s g r i d , r a n g i n g from 64.0 t o 8 7 .3 l i t e r s . An a n a l y s i s o f th e v a r i a t i o n i n sample s i z e was made and th e r e l a t i o n s h i p o f sam ple s i z e to e a c h APPENDIX FIGURE D-15 A D ia g ra m m a tic R e p r e s e n t a t i o n o f th e I n h a b i t a n t s o f a O ne- Q u a r t e r S q u a re M eter P l o t o f t h e L i s t r i o l o b u s A s s o c i a t i o n . The D iagram i s B ased upon 7 S a m p le s. (The l a r g e r a n im a ls a r e r e p r e s e n t e d i n t h e i r r e l a t i v e s i z e p r o p o r t i o n s t o t h e a r e a . Many i m p o r t a n t s m a l l e r s p e c i e s a r e n o t shown) S y m b o ls: A, c e r i a n t h i d anemone; F, P i n n i x a sp p . B, A s y c h is l a c e r a G, G l y c e r a c a p i t a t a Cr P h o r o n o p s is s p . Ht P e c t i n a r i a c a l i f o r n i e n s i s D, L i s t r i o l o b u s p e lo d e s J , P i s t a d i s j u n c t a E r G ly c e r a r o b u s t a K, Compsomyax s u b d la p h a n a L, C a l l l a n 'a s s a s p . 549 550 Figure D-15 551 o f t h e b i o l o g i c a l v a r i a b l e s was a g a i n t e s t e d by c a l c u l a t i n g _r v a l u e s ; v a l u e s r a n g e d from - 0 .3 7 6 to + 0 .3 7 5 . The v a l u e s f o r p h o r o n id s t a n d i n g c ro p ( - 0 . 3 7 6 ) , p o l y c h a e t e s t a n d i n g c r o p ( - 0 . 3 4 6 ) and S a x i c a v e l l a num ber o f s p e c im e n s ( + 0 . 3 7 5 ) , w ere above ( o r b elo w i n th e c a s e o f t h e n e g a t i v e v a l u e s ) th e 5 p e r c e n t l e v e l o f s i g n i f i c a n c e . N e v e r t h e l e s s , t h e r e i s good r e a s o n to d i s c o u n t th e a p p a r e n t c o r r e l a t i o n o f t h e s e p a r a m e t e r s w i t h sam p le volum e and t o make d i r e c t com p a r i s o n w i t h o u t w e i g h t i n g th e d a t a . F i r s t , t h e d i s t r i b u t i o n o f r_ v a l u e s a b o u t th e 0 .0 0 0 c o r r e l a t i o n l e v e l s u g g e s t s t h a t t h e r e i s l i t t l e r e l a t i o n s h i p b e tw e e n sam p le volume and t h e m a g n itu d e o f t h e s t a n d i n g c ro p o r t h e a b u n d an ce o f s p e c im e n s f o r t h e s a m p le s fro m t h i s g r i d . S e c o n d ly , th e sa m p le volum e c o e f f i c i e n t s o f v a r i a t i o n (C = S ta n d a r d D e v ia tio n /m e a n .1 0 0 ) a r e e x c e e d i n g l y s m a l l (5 t o 9 p e r c e n t ) , and th e s m a l l e s t C v a l u e f o r any b i o l o g i c a l p a r a m e te r i s 24 p e r c e n t . F i n a l l y , a l l o f t h e g r a b h a u l s i n th e L i s t r i o l o b u s g r i d e x c e e d 4 2 .1 l i t e r s , th e volum e a t w h ic h t h e OPB a c h i e v e s t h e maximum a r e a l c o v e r a g e ( B a r n a r d and J o n e s , 1 9 6 0 ). L i s t r i o l o b u s c o m p ris e s 81.5% o f t h e t o t a l s t a n d in g c ro p o t th e g r i d s a m p le s . V a lu e s ra n g e d b e tw e e n 3 9 7 .6 and 1 6 2 9 .2 g,/ms (m ean, 9 4 4 .4 g/m2 ) . The mag n i t u d e and p a t t e r n o f v a r i a t i o n i n t h e L i s t r i o l o b u s s t a n d i n g c ro p i s v e r y s i m i l a r t o t h a t f o r t o t a l s t a n d i n g c r o p . V a lu e s d e c r e a s e p r o g r e s s i v e l y fro m t h e f i r s t (S e p te m b e r) to t h e l a s t ( J u n e ) s a m p lin g p e r i o d . The C v a l u e s i n c l u d e t h e l o w e s t o b s e rv e d i n e i t h e r o f The c o m m u n itie s s t u d i e d . The c o e f f i c i e n t o f v a r i a t i o n f o r L i s t r i o l o b u s s p e c im e n s p e r m3 i s a l s o low ( 27%) and e q u a l s t h a t f o r s t a n d i n g c r o p . The mean num ber o f s p e c im e n s p e r m ® i s 92 and r a n g e s fro m 28 t o 128. 552 I n c o n t r a s t t o th e A m p h io d ia -C a r d ita commu n i t y , p o l y c h a e t e s co m p rise a much s m a l l e r f r a c t i o n o f t h e t o t a l s t a n d i n g c ro p . V alu es f o r i n d i v i d u a l s a m p le s r a n g e d from 1 3 .6 t o 2 7 9 .2 g /m 3 (mean, 6 7 . 2 ) . P h o r o n id s fo rm a s t a n d i n g c ro p f r a c t i o n s i m i l a r i n m a g n itu d e t o p o l y c h a e t e s i n th e L i s t r i o l o b u s commu n i t y . V a lu e s f o r t h e s e o rg a n ism s ra n g e from 1 5 .2 t o 8 0 .0 g./m2 (mean, 3 9 .2 ) and th e number o f s p e c i mens ra n g e fro m 24 t o 304,/m3 (mean, 1 4 0 ). M o llu sk s t a n d i n g c ro p i s much lo w e r i n t h e L i s t r i o l o b u s community th a n i n th e A m ph io d ia- C a r d i t a a s s o c i a t i o n . Mean v a l u e s a r e n e a r l y th e same ( c a . 8 g,/m2) f o r a l l s e a s o n a l g ro u p s b u t i n d i v i d u a l sa m p le s r a n g e fro m 2 . 4 - 2 0 . 0 g /m 2. V a r i a t i o n ( | | ) r a n g e s from 35 t o 70%. (G. J o n e s , 1964, p .Ifl) S a x i c a v e l l a p a c i f i c a , t h e m ost c h a r a c t e r i s t i c m o llu s k o f t h i s a s s o c i a t i o n , h a s a v e r y c l o s e a s s o c i a t i o n , 97 p e r c e n t ( i n g r i d s a m p le s ) , w i t h L i s t r i o l o b u s . The 980 sp e c im e n s o f S a x i c a v e l l a c o l l e c t e d i n th e 36 g r i d sa m p les had a mean p o p u l a t i o n d e n s i t y o f 120 s p e c im e n s /m 3 ( r a n g e , 4 to 412) and a mean s t a n d i n g c ro p (w et w e ig h t) o f 4 g /m 3. B ased on t h e s e d a t a , th e mean w e ig h t o f th e " a v e r a g e i n d i v i d u a l ” S a x i c a v e l l a i s 0 .0 3 7 g /s p e c im e n . T h is i s s m a ll i n c o m p a riso n w ith L i s t r i o l o b u s , th e " d o m in a n t" o rg a n ism o f t h e a s s o c i a t i o n , w h ic h a v e r a g e s a b o u t 10 g /s p e c im e n . Con s e q u e n t l y , d e s p i t e i t s v e r y c l o s e e c o l o g i c a l a s s o c i a t i o n , S a x i c a v e l l a was n o t d e s i g n a t e d a " c o -d o m in a n t" i n t h i s b e n t h i c a s s o c i a t i o n by B a rn a rd and Hartm an (1 9 5 9 ). The n in e s t a t i o n L i s t r i o l o b u s s a m p lin g g r i d (G. J o n e s [ b l , in S te v e n s o n , 1961) was a l s o exam ined by Pomeroy ( p e r s . comm.) f o r s p a t i a l and te m p o ra l v a r i a t i o n (AHF:USC, 1965. The o b s e rv e d d i s t r i b u t i o n s o f t h e number o f s p e c im e n s o f s i x s p e c i e s i n sa m p le s fro m t h i s g r i d were com pared w i t h the d i s t r i b u t i o n to be e x p e c te d i f v a r i a b i l i t y was c o m p le te ly random . T h r e e s p e c ie s ., L i s t r i o l o b u s p e l o d e s ( t h e a s s o c i a t i o n " d o m in a n t” ) , G ly c e ra s p p . and C e r a t o c e p h a l a £ . a m e r ic a n a , show o n ly s l i g h t d e v i a t i o n s fro m random ness w ith r e s p e c t t o tim e and s p a c e . P e c t i n a r i a c a l i f o r n i e n s i s , S a x i c a v e l l a p a c i f i c a and p h o r o n id s showed s i g n i f i c a n t l y d i f f e r e n t c o u n ts f o r t h e d i f f e r e n t s a m p lin g p e r i o d s . L a rg e s c a l e s e a s o n a l d i f f e r e n c e s w ere o b s e rv e d f o r P e c t i n a r i a . A l l s p e c i e s b u t G ly c e r a showed s p a t i a l v a r i a t i o n o r " s p o t t i n e s s " (= " p a t c h i n e s s " o f H artm an) (AHF:US€, 1 9 6 5 ). The N o t h r i a - T e l l i n a A s s o c i a t i o n B a r n a r d (1963) has d e s c r i b e d f o u r k i n d s o f s a n d - d w e l l i n g a s s e m b la g e s ; t h r e e h e c o n s id e r e d " f a c i e s " o f t h e N o t h r i a -T e l l i n a a s s o c i a t i o n a n d th e f o u r t h was d e s c r i b e d as a d i s t i n c t a s s o c i a t i o n "d o m in a te d " by t h e p o l y c h a e t e P r i o n o s p i o m alm g ren i. One o f th e N o t h r i a - T e l l i n a a s s o c i a t i o n " f a c i e s " and th e P r i o n o s p i o a s s o c i a t i o n a r e com ponents o f th e s h a l l o w (2 t o 10.1 m e t e r s ) n e a r s h o r e sa n d b o tto m s ; t h e s e two a s se m b la g e s a re d e s c r i b e d l a t e r i n t h e s e c t i o n on t h e n e a r s h o r e fa u n a . The N o t h r i a — T e l l i n a a s s o c i a t i o n o c c u r s a lo n g t h e e n t i r e l e n g t h o f th e s o u t h e r n C a l i f o r n i a m a in la n d s h e l f . On m ost p a r t s of t h e s h e l f t h i s s h a ll o w - w a t e r s a n d f a u n a i s 554 r e s t r i c t e d t o a n a r ro w ban d n e a r s h o r e . H ow ever, i n c e r t a i n a r e a s , s u c h a s t h e w e s t e r n p o r t i o n o f t h e S a n ta B a r b a r a s h e l f , o f f V e n tu r a , e x t e n s i v e sa n d b o tto m s p r e s e n t an a c c e p t a b l e b i o t o p e w h ereb y t h e two d e e p e r d w e l l i n g f a c i e s o f t h i s a s s o c i a t i o n can e x t e n d f a r fro m s h o r e . The N o t h r i a - T e 11i n a a s s o c i a t i o n p o p u l a t e s 18 p e r c e n t o f t h e s h e l f b o tto m ( B a r n a r d [ a ] , i n S t e v e n s o n , 1 9 6 1 ) . I n t h e N o t h r i a - T e l l i n a a s s o c i a t i o n t h e r e i s a d i f f e r e n c e i n t h e d e p t h d i s t r i b u t i o n o f t h e two ’’d o m in a n ts ” . T e l l i n a b u t t o n i o c c u r s i n g r e a t e r d e n s i t i e s t h a n N o t h r i a e l e g a n s on t h e s h a l l o w e r b o tto m s . I n an a n a l y s i s o f 16 s a m p le s ( B a r n a r d , 1963, T a b le 3) T e l l i n a a v e r a g e d 385 i n d i v i d u a l s / m 3 i n d e p t h s o f 38 t o 54 f e e t ( 1 1 .6 t o 1 6 .5 m) b u t o n ly 100/m 3 i n d e p t h s o f 76 t o 92 f e e t ( 2 3 . 2 - 2 8 . 1 m ). I n t h e same c i r c u m s ta n c e , N o t h r i a p o p u l a t i o n d e n s i t i e s w ere 48,/m2 com pared t o 132/m 2 . D e p th , t h e n , was u s e d a s a b a s i s f o r d i s t i n g u i s h i n g two ’’f a c i e s ” i n t h i s a s s o c i a t i o n ( B a r n a r d , 1 9 6 3 ). The n u m e r i c a l l y i m p o r t a n t s p e c i e s a r e th e same i n b o t h s u b d i v i s i o n s o f t h e a s s o c i a t i o n , b u t t h e i r ra n k o r d e r i s d i f f e r e n t . I n N o t h r i a - h i g h s a m p le s t h e i m p o r t a n t s p e c i e s a r e M ageIona s p p . (mean, 2 4 4 /m 3) , P r i o n o s p i o m a lm g re n i (131,/m2) , N e p h ty s s p . ( 7 5 /m 2) , G o n iad a s p . (72,/m3) , C h a e to z o n e s p . (62,/m3) , H a p l o s c o l o p l o s e l o n g a t u s (59,/m 3) , A r i c i d e a s p p . (52,/m3) , D i a s t y l o p s i s t e n u i s (30./m 2) , and O l i v e l l a b a e t i c a (4,/m3) (A p p en d ix F i g u r e D - 1 6 ) . I n APPENDIX FIGURE 16 A P i c t o r i a l R e p r e s e n t a t i o n o f th e N o t h r i a - T e l l i n a A s s o c i a t i o n i n D ep th s o f 30 -9 5 F e e t ( 1 0 .1 - 2 8 .0 m e t e r s ) , Showing th e A verage C o m p o sitio n of 8 Sam ples "Heavy i n N o t h r i a ," A rra n g e d on a 0 .2 5 S q u are M ete r P l o t and Drawn to S c a l e . S ym bols: A, N o t h r i a e l e g a n s B, T e l l i n a b u t t o n i C, P r i o n o s p i o sp p . D, N ep h ty s s p . E, Macoma y o l d i f o r m i s F , C h a e to z o n e c o ro n a G, G o n iad a s p . H, M ageIona sp p . I , H a p l o s c o l o p lo s e l o n g a t u s . The l a r g e r a z o r clam i s S o le n s p . The l a r g e s t a r f i s h i s A s t r o p e c t e n c a l i f o r n i c u s . ( F ig u r e 1, B a r n a r d , 1 9 6 3 .) 555 Figure D-16 0 C? 557 T e l l i n a - h ig h s a m p le s t h e o r d e r o f t h e s e same s p e c i e s i s as f o l l o w s : C h a e to z o n e s p . (m ean, 3 3 l/m 3 ) , D i a s t y l o p s i s t e n u i s ( 2 1 l/m 3 ) , H a p l o s c o l o p l o s e l o n g a t u s (196/m 3 ) , N e p h ty s sp . (9 9 /m 3 ) , M agelftna s p p . (92/m 2 ) , G o n ia d a s p . ( 62/m2 ) , A r i c i d e a sp p . (50/m 2 ) and O l i v e l l a b a e t i c a (28/m 3 ) (A ppendix F i g u r e D -1 7 ). The mean s t a n d i n g c r o p i n t h i s a s s o c i a t i o n ( a l l s u b d i v i s i o n s co m b in ed ) i s 242 g/m3 ( B a r n a r d l a ] , i n S t e v e n s o n , 1 9 6 1 ) . The D i o p a t r a A s s o c i a t i o n G rab s a m p le s c o l l e c t e d fro m s h a ll o w - w a t e r a r e a s o f t e n c o n t a i n m i x t u r e s o f one or more s u b s t r a t e t y p e s , i n c l u d i n g : b r o k e n r o c k , p e b b l e s and g r a v e l , c o a r s e s a n d , sand o r e v e n mud. B i o l o g i c a l d e b r i s , s u c h a s s h e l l f r a g m e n t s , b r o k e n k e l p and worm t u b e s , i s o f t e n c o n s p ic u o u s . Some s a m p le s c o n t a i n much p l a n t d e t r i t u s and h a v e a s l i g h t odor o f h y d ro g e n s u l f i d e . P r e l i m i n a r y c l a s s i f i c a t i o n o f sa m p le s c o l l e c t e d fro m su ch com plex z o n e s h a s b e e n made on t h e b a s is o f a f r e q u e n t l y o c c u r r i n g e l e m e n t , th e l a r g e t u b e - b u i l d i n g worm D i o p a t r a o r n a t a . T h is a s s o c i a t i o n c o v e r s a p p r o x i m a te l y 4 p e r c e n t o f th e b o tto m o f t h e m a in la n d s h e l f . I t i s d i s c o n t i n u o u s l y d i s t r i b u t e d p a r t i c u l a r l y a ro u n d r o c k y h e a d l a n d s an d n e a r k e l p b e d s o v er t h e e n t i r e l e n g t h o f th e m a in la n d s h e l f o c c u r r i n g i n s h o r e o f t h e s h a l l o w - b o t t o m sand a s s o c i a t i o n s . The c o a r s e s e d im e n t s i n h a b i t e d b y t h i s : b i o t a have a mean m ed ian d i a m e t e r o f 0 .1 8 3 mm. A h i g h APPENDIX FIGURE D-17 A P i c t o r i a l R e p r e s e n t a t i o n o f t h e N o t h r i a - T e l l i n a A s s o c i a t i o n i n D e p th s o f 38 -9 2 F e e t ( 1 1 .6 - 2 8 . 0 M e t e r s ) , w i t h "H igh D e n s i ty o f T e l l i n a and Low D e n s i ty o f N o t h r i a . t. t Drawn t o S c a le on a O n e -Q u a rte r S q u a re M e te r P l o t . ( F ig u r e 2, B a r n a r d , 1 9 6 3 ). 558 559 Figure D-17 ‘ O l V . v N r ^ C N J V x ^ ^ x ^ ^ t Cj W o ^ *n *-* 0 ’(0 ^ „ 0 \r £ ^ T c J £>, . ' c : o fvV^ < !'J'T ' V > - < - 1 ^ O ^ S y ^ o ' * ' " ° ° * n , * / - J <• ' “> H S'T ^ ‘ ^ r> * y V " ‘ - V > ^ " J u r - w ^ . ■ o?r^i ° r /' , / l * /■ « g O ~ o * . t \ J ^ > 1 <nf C\ ± ’ o> r ^ t 0 -* C ^ ^ ^ ✓ * > < • u a ^ < 9 , * * £ > ^ 3 v C \ ~ > ^ rx V t n \ °)|Co ,r\° “ *n ■ 0 ^ / f t o * ^ 0 v r c °7 tr^ T^ll1 -r^f0 > V * n ^ \ * v / ^ - u ) 5601 s t a n d i n g c r o p , 720 g/m2 , c h a r a c t e r i z e s t h i s f a u n a (B a rn a rd [ a ] , i n S te v e n s o n , 1 9 6 1 ). I n s e v e n sa m p le s s e l e c t e d as r e p r e s e n t a t i v e o f t h i s ty p e o f e n v iro n m e n t t h e p o p u l a t i o n d e n s i t y o f D i o p a t r a o r n a t a a v e r a g e d 288/m 3 . O th e r n u m e r i c a l l y i m p o r t a n t s p e c i e s o c c u r r i n g i n a t l e a s t 6 o f th e 7 s a m p le s i n c l u d e d t h e p o l y c h a e t e s D o r v i l l e a a r t i c u l a t a (1 9 6 /m 2) and Lum- b r i n e r i s sp p . (2 1 6 /m 2) and t h e c r u s t a c e a n s A o ro id e s c o lu m b ia e (3Q8./ms ) , P h o t i s s p p . (288,/m3) , E u r y s th e u s th o m p so n i (116,/m3) , I s c h y r o c e r u s spp. (9 2 /m 2) and u n i d e n t i f i e d h e r m i t c r a b s (76,/m2) . C o n s i s t e n t l y p r e s e n t a t low f r e q u e n c y w ere u n i d e n t i f i e d c r a b s (32./m2) , th e p o l y c h a e t e P h e r u s a sp p . (20,/m2) and t h e g a s tr o p o d N a s s a r i u s c o o p e r i (16,/m2) . The p e le c y p o d Solemya p an a m e n sis was a b u n d a n t i n t h r e e s a m p le s from b o tto m s a s s o c i a t e d w ith k e l p b e d s . . . . S p e c ie s o f t h i s gen u s h av e an i n t e r e s t i n g d i s t r i b u t i o n i n s o u t h e r n C a l i f o r n i a . They have b e e n c o l l e c t e d fro m t h e s h e l f , t h e su b m a rin e c a n yo n s t h a t c r o s s th e m a in la n d s h e l f , and fro m San N i c o l a s and T a n n e r B a s in s ( Solemya ? j o h n s o n i D a l i ; H artm an and B a r n a r d , 1 9 6 0 ). Emery (1960) r e p o r t s h ig h n i t r o g e n p e r c e n t a g e s o f 8.1% and 11.7% r e s p e c t i v e l y from th e s e d im e n ts o f t h e s e o u t e r d eep b a s i n s . On t h e s h e l f , Solemya p a n a m e n sis i s a s s o c i a t e d w i t h a r e a s o f o r g a n i c d e b r i s s u c h a s r e g i o n s o f k e l p , o i l s e e p s , and o t h e r a r e a s o f n a t u r a l o r g a n i c ma t e r i a l . O th e r s p e c i e s o f t e n a s s o c i a t e d w i t h su c h a r e a s and o c c u r r i n g a t t h i s s t a t i o n n e a r G a v io ta a r e th e g a s tr o p o d N a s s a r i u s c o o p e r i (F o rb e s ) and th e p e le c y p o d Lima d e h i s c e n 's "C6n r a d . N a s s a r i u s i s a s c a v e n g e r and h a s b een c o l l e c t e d i n g r e a t num bers fro m th e a r e a n e a r th e t e r m i n u s o f th e Los A n g e le s 561 o C i t y O u t f a l l i n S a n ta Monica Bay. Lima d e h i s c e n s o c c u r s a t h i g h e s t c o n c e n t r a t i o n s i n a s s o c i a t i o n w i t h t h e p o l y c h a e t e C h a e to p t e r u s v a r i o p e d a t u s ( R e n ie r ) i n t h e a r e a o f f I n s p i r a t i o n P o i n t on! t h e P a lo s V erd es s h e l f . H ere th e tu b e s o f C. v a r i o p e d a t u s fo rm l a r g e m ats on b o tto m s o f b la c k e n e d s e d im e n ts h ig h i n o r g a n i c d e b r i s * _________ ^ C o l l e c t e d by t h e ’ H y p e rio n E n g i n e e r s , 1 .8 km " seaw ard o f th e O ne-M ile O u t f a l l i n S a n ta Monica Bay ( C o l l e c t o r , C. I m e l ) , Decem ber, 1958; a b o u t 10,000 sp e c im e n s c o l l e c t e d c l i n g i n g t o a 0 .6 m e te r d i a m e t e r b a i t e d c r a b n e t . (G. J o n e s , 1 964, p p . 53-55) H artm an ( i n S te v e n s o n , 1961) r e f e r s t o t h i s a s s o c i a t i o n as an a s s o c i a t i o n o f th e p o l y c h a e t e s D i o p a t r a o r n a t a and N o t h r i a e l e g a n s ( nThe D i o p a t r a o r n a t a - N o t h r i a e le g a n s a s s o c i a t i o n 11) . The b a l a n c e b etw een t h e s e two f a u n a l e l e m en ts v a r i e s ; D i o p a t r a i n c r e a s e s i n im p o rta n c e i n a r e a s w i t h k e l p ; N o t h r i a te n d s t o r e p l a c e D i o p a t r a w here k e l p i s s c a n t y o r l a c k i n g and w here s u b s t r a t e s a r e sa n d y . The i d e a t h a t D i o p a t r a a n d N o t h r i a a r e l i n k e d i n an a s s o c i a t i o n would s u g g e s t a r e l a t i o n s h i p b e tw e e n two w id e s p r e a d s h a ll o w w a te r a s s o c i a t i o n s o f t h e m a in la n d s h e l f . The N o t h r i a s t i g m a t i s - S p jo p h a n e s bombyx A s s o c i a t i o n The N o t h r i a s t i g m a t j s - S p io p h a n e s bombyx a s s o c i a t i o n i n h a b i t s d e p o s i t s o f c o a r s e r e d ( i r o n o x i d e - s t a i n e d ) s a n d s on t h e S a n ta M onica (1 0 -3 0 m ), San P e d ro (5 -9 0 m ), P a lo s V erd es (1 0 -9 0 m) and San D iego (1 8 -4 0 m) s h e l v e s . These r e l i c d e p o s i t s a r e t h e m ost d i s t i n c t i v e c o a r s e - f r a c t i o n ty p e on th e s h e l f . The mean m ed ian d ia m e te r o f t h i s 562 d e p o s i t e x c e e d s 0 .3 0 0 mm. T h is a s s o c i a t i o n p o p u l a t e s 4 p e r c e n t o f th e s h e l f . The mean s t a n d i n g crop is. 170 g,/m2 (B a r n a rd [ a ] , i n S te v e n s o n , 1961). . . . . The m a c ro fa u n a o f t h i s b i o t o p e i s e q u a l l y i n t e r e s t i n g . The p o l y c h a e t e s N o t h r i a s t l g m a t j s and S p io p h a n e s bombyx dominate*! CFFher c o n s p ic u - ous s p e c i e s i n c l u d e t h e c e p h a lo c h o r d a te B r a n c h l o - stom a c a l i f o r n i e n s e Andrew, t h e sand c r a b B l e p h a r i p o d a o c c i d e n t a l i s R a n d a l l , th e s i p u n c u l i d S ip u n c u lu s nudus JLinnaeas and t h e e c h in o d e rm L o v e n ia c o r d l f o r m i s A. A g a s s i z . M o llu s c a n e le m e n ts o f f h i s a s s o c i a t i o n i n c l u d e d t h e p e le c y p o d s C a r d i t a b a i l y i B u rc h , G ly c y m e ris c o r t e z i a n a P a l l and B e i l i n a b u t t o n i , a n d t h e g a s t r o p o d s M lc ra n e llu m c r e b r i c i n c t u m ( C a r p e n t e r ) , H a l i s t y l u s s u b p u p o id e u s T ry o n , P h a s i a n e l l a s p . , A la b in a s p . t M a r g a r i t e s s p . , an d O l i v e l l a b a e t T c a . (G. J o n e s , 1964, p . 57) The C h a e to p t e r u s A s s o c i a t i o n The C h a e to p t e r u s a s s o c i a t i o n i n h a b i t s o n ly a s m a ll a r e a , l e s s th a n 5 p e r c e n t o f th e s h e l f . I t i s th e m o st p ro m in e n t f e a t u r e o f th e b i o t a of t h e P a lo s V erd es s h e l f . . . . . H ere on b l a c k san d and m ixed b o tto m s , i n r e l a t i v e l y s h a llo w d e p t h s c l o s e t o s h o r e , th e p a r c h ment worm C h a e t o p t e r u s v a r i o p e d a t u s fo rm s m asses o f i t s t u b e s . P r ominen t l y a s s o c i a t e d w i t h i t i s t h e p e le c y p o d Lima d e h i s c e n s (maximum, 4 0 4 /m 2) . O th e r m o llu s k s a s s o c i a t e d w i t h t h i s community a r e th e g a s tr o p o d s N a s s a r i u s c o o p e r i , N a s s a r i u s p e r p i n g u i s , Conus ca 1 i f o r n i c u s Hind's and M i t r e l l a c a r r n a t a , and th e p e le c y p o d s Solem ya pafoamensls and P a r v l l u c i n a t e n u i s c u l p t a . O th e r c o n s p ic u o u s s p e c i e s o f t h i s a s s o c i a t i o n a r e th e p o l y c h a e t e s D i o p a t r a o r n a t a and P h y l l o c h a e t o p t e r u s p r o l i f i c a P o t t s and th e e lb o w c r a b H e t e r o c r y p t a o c c i d e n f a T I s (D a n a ). S t a n d in g c ro p v a l u e s m ea su re d on t h i s com m u n ity a r e h i g h e r t h a n any on t h e s h e l f e x c e p t f o r th e L i s t r i o l o b u s a s s o c i a t i o n . I n C h a e to p e r u s - Lima a s s o c i a t i o n s a m p le s s t a n d i n g cro p v a l u e s I n e x c e s s o f 1 ,3 0 0 g/m 3 h a v e been r e c o r d e d . T h is a s s o c i a t i o n h a s b een d e s c r i b e d p r e v i o u s l y by 563 Hartman (1955) and Barnard, Hartman and Jones (1959). Fauna o f th e O u te r S h e l f and S lo p e Seaw ard o f t h e A m p h io d ia- C a r d i t a a s s o c i a t i o n o f t h e n o r t h e r n p o r t i o n o f th e m a in la n d s h e l f and o f t h e A m phiodia a lo n g t h e s o u t h e r n p o r t i o n s o f th e s h e l f , b o tto m s o f t h e d e e p e r s h e l f and s lo p e a r e p o p u l a t e d by f o u r a s s e m b la g e s o f b ro a d d i s t r i b u t i o n . One i s " d o m in a te d 1 1 by th e l a r g e o p h i u r o i d A m phiacantha a m p h a c a n th a , a se c o n d by a n o t h e r l a r g e o p h i u r o i d , A m phiodia d i g i t a t a , t h e t h i r d by two p o l y c h a e t e s , th e b r i s t l e worm C h l o e i a p i n n a t a and th e cone worm P e c t i n a r i a c a l i f o r n i e n s i s , and t h e f o u r t h by t h e tu b e d w e llin g p o l y c h a e t e s P l a t a d l s j u n c t a and N o t h r i a p a l l i d a . T h e P e c t i n a r i a - C h l o e i a a s s o c i a t i o n i n h a b i t s s e d i m ents w i t h a mean m edian d i a m e t e r o f 0 .0 5 8 mm. I t p o p u l a t e s a b o u t 4 p e r c e n t o f th e s h e l f . S t a n d in g c ro p a v e r a g e s 294 g,/m2. T he A m phiacantha am p h acan th a a s s o c i a t i o n c o v e r s a somewhat s m a l l e r a r e a , 3 p e r c e n t o f t h e s h e l f . S e d im e n ts a r e s i m i l a r , w ith a mean m ed ian d i a m e t e r o f 0 .0 4 7 mm. S ta n d in g c ro p a v e r a g e s 207 g /m 2. The A m phiodia d i g i t a t a a s s o c i a t i o n p o p u l a t e s o n ly 1 p e r c e n t o f th e s h e l f a r e a . S e d im e n ts a r e somewhat c o a r s e r th a n i n t h e o t h e r two a s s o c i a t i o n s ; mean m edian d ia m e te r i s 0 .0 8 7 mm. S ta n d in g c r o p a v e r a g e s 272 g,/m2 ( B a r n a rd , [a] i n S te v e n s o n , 1 9 6 1 ). O n ly th e P e c t i n a r i a - C h lo e ia a s s o c i a t i o n h as b e e n sam pled t o any e x t e n t . In a p r e l i m i n a r y a n a l y s i s u t i l i z i n g 564 six representative samples, Pectinaria californiensis had a mean population density of 240,/ra2, Chloeia pinnata averaged 140,/ms. Other numerically important species in these samples included the following: unidentified ostracods (712,/m2), Amphiodia urtica (244,/m2) , Ampelisca macrocephala (220,/m2), Adontorhina cyclia (88,/m2), Paraonis gracilis (80/m2), Paraphoxus bicuspidatus (64,/m2), Amphipholis squama ta ( 40/m2 ) , Tellina carpenteri ( 32,/ m2 ) and Amygdalum pallidulum (20,/m2). The large sea urchins Brisaster townsendi and Br is sops is pacific.a comprise a considerable portion of the standing crop in all three slope associations. The Pista disjuncta-Nothria pallida association is incompletely described (Barnard, Hartman and Jones, 1959). Minor Associations Barnard ([a], in Stevenson, 1961; and in AHF:USC, 1965) has described a number of minor associations. Possibly the following communities are rec ognizable, but they are of small extent in southern California. Most of them have been recovered in less than five samples, but they are distinct types of assemblages which eventually will be determined as special environments of small areal extent. Den<3raster sp. The sand dollar community in sands' in shallow water which may be mixed with Chaetopterus. 2. Ophiur lutkeni'. A deep-water ophiuroid assemblage. 3. Ophiothrlx spiculata. An epifaunal com munity dominated by this ophiuroid, but perhaps better keyed to sessile organisms such as sponges and tunicates. 565 4. Ampelisca. A deep-water gravel community dominated by this tube-building amphipod. PherUjSa-Qnuphis. A dominant complex re covered in three samples around the Whites Point outfall to a near exclusion of other animal species. Both animals are poly chaetes. 6. Pinnixa. This burrowing crab has been found to dominate several samples in the Nothria elegans-Tellina buttoni comiriunity, and it may simply be a subdivision of that community. However, Pinnixa communities have been described as such in the litera ture. 7. Macoma. One sample was dominated by this clam. This kind of community is wide spread in Arctic and subarctic waters, but is of minor importance in southern California. ^apltella. This polychaete, reported as an indicator of fresh water and also of polluted areas in enclosed bays and harbors, dominated several samples. One of these samples, AHF 4912, was probably near an undersea spring. Two or three of the others were probably indicative of natural pollution as a result of the metabolic activities of other epifaunal animals, whose fecal matter falls to the bottom and provides a rich organic mud. This is especially the con dition in beds of Diopatra in kelp and algal fields. 9. Tharyx. This tube-building worm dominates a number of samples on the San Pedro shelf just off the breakwater. It might be con sidered an indicator of low levels of pollu tion, either man-made or natural, because the animal also dominates other samples where naturally produced dark gray or black sediments occur. Reish (1959 considers Tharyx parvus an indicator of ’'healthy bottom"in Los Angeles Harbor. Notwithstand ing, some of the muds it occupies are black and, for open sea areas, this is most certain ly indicative of an oversupply of organic matter. Species of Tharyx are widespread and numerous through about 15% of the total samples taken, and their presence alone is not an indicator of pollution. Perhaps the numerical frequency in relation to 566 surrounding samples may be of some use in pinpointing degrees of pollution. (p. 27) Barnard’s ([a], in Stevenson, 1961) discussion of the Amygdalum association properly belongs here. 10. Amygdalum. This assemblage is simply an indicator of mixed rubbly bottom with shaley pebbles where this nesting clam lives. No doubt a number of micro- communities of both infaunal and epifaunal nature are mixed in this association, but there are not sufficient samples for an intensive analysis. This association is particularly concentrated on the middle Santa Monica shelf. Pour other minor associations, dominated by Sipuncuius nudus, Branchiostoma californiense, Spiophanes missionensis and Sthenelannella uniformis respectively, have been recognized but not described (Appendix Table 3; also see Barnard, 1963). The Nearshore Fauna, 2 to 10 Meters Sandy beaches predominate (83.5 per cent) along the length of the southern California shoreline; rocky shores comprise the remaining 16.5 per cent (G. Jones, 1964). This distribution approximates Barnard’s estimate (Barnard [a], in Stevenson, 1961) of 15.2 per cent sublittoral rock and 78.3 per cent sands and silty sands for depths to 18.3 meters on the mainland shelf. It is reasonable to assume that, in the depth zone sampled in the nearshore investiga tion, rock constitutes not more than 20 per cent of the area. Thus, a long strip of sandy sea-bottom, occasionally 567 broken by areas of rock, extends along the entire length of the mainland shelf. The inner portion of this region, near the surf zone, is a relatively harsh environment; wave ac tion causes cut and fill erosion and deposition makes the bottom unstable (JEmery, 1960). The shallow or nearshore part of the shelf (2 to 10.1 meters deep) was sampled with a 0.1 m3 Van Veen grab from the motor launch of the Velero IV. A total of 119 samples were collected; of these 100 were completely sorted; only 52 samples were completely analyzed. These 52 samples serve as the basis for estimates of population density in this shallow water zone. The mean number of specimens per square meter for the nearshore zone is 2800 (Hartman, Barnard and Jones, 1960). This is well below the estimate of 3903 specimens per square meter for invertebrate population density on the shelf in depths over 10.1 meters reported by Barnard and Given (1960). A part of this difference may be due to the use of two different techniques of sampling in the two depth zones; however, the use of a finer screen mesh, 0.495 mm, to process the samples from shallow water would tend to raise the figure for the population density of the near shore zone. Very likely the difference, about 1000 speci mens per square meter, is a real one. The abundance of polychaetous annelids does not ap pear to decrease in shallow nearshore sandy sediments; 568 based on 52 samples the average density of polychaetes is 1,640 per square meter compared with an estimate for the deeper offshore zone of 1,420 per square meter. These fig ures are similar considering that differing methods were used for their determination. Of the 95 polychaete species collected in these samples only three were predominant: Prionospio malmgreni, Nephifcys caecoides and Goniada littorea (Hartman, Barnard and Jones, 1961; and in AHF:USC, 1965). Crustacean population density on the shallow sands of the nearshore is lower than on the deeper outer part of the shelf. The average crustacean population in depths over 10.1 meters is 1,350 animals per square meter; in the 52 samples collected in depths from 2 to 10.1 meters these animals averaged only 310 per square meter. The most abun dant species are the cumacean Diastylopsis tenuis (86l/m2) and the amphipods Paraphoxus epistomus, P. bicuspidatus and Mandibulophoxus uncirostratus (Hartman, Barnard and Jones, 1960 and in AHFrUSC, 1965). Echinoderms were totally absent from 49 of 102 sam ples collected from the shallow inshore sands and analyzed for this group. Only 14 species, most at low population densities, were represented in the other 53 samples. The only conspicuous species was the sand dollar Dendraster excentricus, present in 27 samples; in a few areas (Huntington Beach, Oceanside and San Diego) it ’’ dominated" 569 the samples. The maximum number of specimens collected in a single sample was 52 individuals representing a popula tion density of 520/m2; however, many of these were imma ture individuals of very small size (1 to 3 mm). Amphipholis squamata, an ophiuroid, was collected in 8 sam ples; Amphiodia urtica, so frequent and abundant in deeper water, was encountered at only 4 sampling locations (Hart man, Barnard and Jones, 1960; and in AHFrUSC, 1965). Mollusks also showed a decline in density from the mean of 470/m3 for the deeper outer to 180/m2 for shallow nearshore part of the shelf. The important aspects of the molluscan fauna of this zone are described by G. Jones (1964; pp. 59-60): . . . Only a few species were present in a high per centage of the samples examined and only one, Tellina buttoni, was present in more than 50% of the samples. Olivella baetica was encountered in 45% of the samples . . . Seven of the 100 samples failed to contain liv ing mollusks. The remaining 93 had an average of 3.9 species per sample (range 1-17). The mean num ber of specimens per m2 was 178.0 (range 10-1630). On the deeper portions of the shelf (10-90+ m) the mean number of mollusk specimens per m2 is 368.4 (based on 335 OPB samples). The 11 invertebrate macrofaunal species with the highest population densities in the 52 completely analyzed samples from the nearshore portion of the shelf (2 to 10.1 meters) are summarized in Table 6 (Table 1, p. 81, Hartman, Barnard and Jones, 1960; Barnard, 1963, Table 15). Three of these are polychaetes, five are crustaceans, two are 570 mollusks and one is an echinoderm. The Nearshore Associations Barnard (1963, Table 8) assigned the 100 inshore samples to associations following determination of "domi nant” species based on estimates of their relative aggre gate weight in the standing crop. Two associations, the Prionospio malmgreni association and the "shallow-water Tellina buttoni facies" of the Nothria-Tellina association, accounted for 73 samples; two samples were described as be longing to the Dendraster excentricus association; and the remaining samples were not assigned to associations. The 54 samples in the Prionospio association were "dominated” by Prionospio malmgreni alone (47 samples) or in combination with Diastylopsis tenuis (7). "Dominance" in the 19 samples of the Nothria-Tellina association was reported as shared by Tellina buttoni and Diastylopsis tenuis in 15 samples, with each of these species "dominat ing" two samples alone. Miscellaneous "dominants" identi fied in the remaining samples were Tharyx sp.-Goniada littorea (4), Scoloplos armiger (4), Onuphis eremita (2) and Diopatra ornata (2) (Barnard, 1963, Table 8). "The Shallow-water Tellina Facies" of the Nothria-Tellina Association "The shallow-water Tellina facies" (Barnard, 1963) of the Nothria-Tellina association is restricted to depths 571 of 12 to 30 feet (3.7 to 9.1 m). In 11 representative sam ples the ’'dominant" Tellina buttoni had a mean population density of 477/m2 compared to but 0.2/m3 for Nothria elegans. Large numbers of the cumacean Diastylopsis tenuis (mean, 586/m2) usually accompanied Tellina in these samples: this crustacean forms sufficient standing crop that Barnard (1963) considered it a "co-dominant" species. OliVella baetica (and 0. biplicata) is an important element in this shallow water assemblage; its mean density is recorded as 75 specimens/m®, but in 12 of the 100 samples from this zone its density was higher than 130/m2 . Polychaetes make up the other numerically important group of species in this "facies"; included are species listed in the two other "facies" of this association, but their rank order differs somewhat: Prionospio malmgreni (190/m3), Gonjada sp. (Ill/m3), Nepfa'fys sp. (55/m2), Haploscoloplos elongatus (23/m3), Magelona spp. (14/m3), Aricidea spp. (7/m3) and Chaetozone sp. (6/m3). Appendix Figure D-18 is a pictorial representation of 0.25 m2 from this association (Figure 3, Barnard, 1963). The Prionospio malmgreni Association Barnard (1963) describes a shallow water sand "dom inated" by the polychaete Prionospio malmgreni. Organisms of this and the "shallow water Tellina facies" of the Nothria-Tellina association comprised the contents of 72 of APPENDIX FIGURE D-18 A Pictorial Representation of the Nothria-Tellina Associa tion in Depths of 12-30 Feet (3.7-10.1 meters) Termed the "Tellina facies of 'shallow-water1 Nothria-Tellina Communi ty” (See Barnard, 1963, Table 6). Drawn to Scale on a One-Quarter Square Meter Plot. (The snail is Olivella baetica.) (Figure 3, Barnard, 1963.) 572 Figure D-18 1 uS- 7 o ^ 0 4 <3 100 samples collected in the depth range of 2 to 10 meters. However, samples "dominated" by Prionospio were distinct from those "dominated” by Tellina as the two organisms were almost mutually exclusive. Prionospio malmgreni, with a mean population density of 1790/m2 (based on 28 samples), overshadows the other numerically important species in this association. In rank order these are the following: Diastylopsis tenuis (86/m2), Nephtys sp. (53/m2), Goniada sp. (48/m2), Chaetozone sp. (44/m2), Qlivella baetica (35/m2), Haploscoloplos elongatus (33/m2), MageIona spp. (6/m2) and Aricidea spp. (4/m2). Sediments in the Prionos pio association are somewhat coarser (Md. 0.105 mm) than those of the shallow water Tellina facies (Md. 0.063 mm). A pictorial representation of a 0.25 m2 plot from this as sociation is shown in Appendix Figure D-19 (Figure 4, Barnard, 1963). APPENDIX FIGURE D-19 A Pictorial Representation of the Prionospio Association in Depths of 12-30 Feet (3.7-10.1 meters). Drawn to Scale on a One-Quarter Square Meter Plot. (The sand crab is Lepidopa sp.) (Figure 4, Barnard, 1963.) 575 Figure D-19 K ■ A . l- ' r . V > n \ y<- fs / ( ' / '> V V, * • u ^ - -''A , v i 'c? > \ j . ' ■ ' V ) , *v -v > <* ^ !7? r ~ f,, «<< £ . n ^l, <*^yv t ,x""' -' ■ ■ ^ " £ ? N T ? t / 4 V 'S fc I 1 M H , ‘ i o v;/ v ^ * 7 ^ 7 v * ^ ~ o , ^ \ * P > ■"' v ^<7 \ -~0 b c? ^ A > a V - i - "> A -7777771 7V ■ t~ . J X L h - 1 V j $ v / ' I «-_» ~ < 3 7 - 1 r v i 7 7 REFERENCES Allan. Hancock Foundation, University of Southern California, (=AHF:USC, 1959), Oceanographic Survey of the Con tinental Shelf Area of Southern California. 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K., 1926, Methods of mechanical analysis of sediments, University of Iowa Studies in Natural History, ll(ll):l-52. Whittaker, R. H., 1962, Classification of natural communi ties, Botanical Review, 28(l):l-239. Wigley, Ronald L., and McIntyre, A. D., 1964, Some quanti tative comparisons of offshore meiobenthos and macrobenthos south of Martha’s Vineyard, Limnology and Oceanography, 9(4):485-493. 592 Wilson, Donald M., 1956, Quantitative survey of the bentho— nic Mollusca of San Pedro Basin area, southern California, Master’s thesis, University of Southern California, 96 pp. Wimberley, Stanley, 1961 (= Wimberley, in Stevenson, 1961), Marine geology of the southern California mainland shelf, Part 1: Physical properties of sediments, pp. 169-192, in The Oceanography of the Southern California Mainland Shelf (ed. Robert E. Stevenson), v. I, sect. II, 32 pp. , 1964, Sediments of the southern California main land shelf, Doctor of Philosophy Dissertation, University of Southern California, 207 pp. Zenkevitch, L., 1963, Biology of the Seas of the U.S.S.R., Interscience Publishers, New York: John Wiley and Sons, 955 pp. Ziesenhenne, Fred C., 1961 (= Ziesenhenne, in Stevenson, 1961), Systematic list of Echinodermata, pp. 117- 120, in The Oceanography of the Southern California Mainland Shelf Ced. Robert E. Stevenson), v. IY, 120 pp. This dissertation has been microfilmed exactly as received 6 8 -1 6 8 4 JONES, Gilbert Fred, 1930- THE BENTHIC MACROFAUNA OF THE MAINLAND SHELF OF SOUTHERN CALIFORNIA. University of Southern California, Ph.D., 1967 Marine Sciences University Microfilms, Inc., Ann Arbor, Michigan PLEASE NOTE: Not original copy. Several pages have indistinct print. Filmed as received. University Microfilms.

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Asset Metadata

Creator Jones, Gilbert Fred, 1930- (author)

Core Title The benthic macrofauna of the mainland shelf of southern California

School Graduate School

Degree Doctor of Philosophy

Degree Program Biology

Degree Conferral Date 1967-09

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag biology, oceanography,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Mohr, John Luther (committee chair), Chew, Robert M. (committee member), Gorsline, Donn S. (committee member), Savage, Jay Mathers (committee member), Zimmer, Russel L. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c18-590664

Unique identifier UC11359904

Identifier 6801684.pdf (filename),usctheses-c18-590664 (legacy record id)

Legacy Identifier 6801684

Dmrecord 590664

Document Type Dissertation

Rights Jones, Gilbert Fred

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA