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The ecology of the mid-water Amphipoda in the waters over the Santa Catalina and the San Pedro Basins off the coast of southern California

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The ecology of the mid-water Amphipoda in the waters over the Santa Catalina and the San Pedro Basins off the coast of southern California

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Content THE ECOLOGY OF THE MID-WATER AMPHIPODA IN THE W ATERS OVER THE SANTA CATALINA A N D THE SAN PEDRO BASINS OFF THE COAST OF SOUTHERN CALIFORNIA by Gary John Brusca A D iss e rta tio n Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In P a r t i a l F u lfillm e n t of the Requirements fo r the Degree DOCTOR OF PHILOSOPHY (Biology) June 1965 UNIVERSITY O F SOUTHERN CALIFORNIA THE GRADUATE SCHOOL UNIVERSITY PARK LOS ANGELES. CALIFO RNIA 9 0 0 0 7 This dissertation, written by Gary John Brusca under the direction of hk?.....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 Dean Date J u n e . 1 .9.65....................................................... DISSERTATION COMMITTEE [S£E^' Chairman / Copyright by G A R Y J O H N B R U SC A 1966 ACKNOWLEDGMENTS The author i s deeply g r a te f u l to Dr. Russel Zimmer of the Department of Biology, U niversity of Southern C a lifo rn ia , who o ffered constant help and encouragement throughout the planning and development of t h i s study. G ratitude is also expressed to Dr. John Garth of the Allan Hancock Foundation fo r c r i t i c a l l y examining c e rta in aspects of the study and fo r ed itin g th e m anuscript. Thanks are extended to the follow ing members of the fa c u lty of the Department of Biology, U niversity of Southern C a lifo rn ia, fo r t h e i r a ssista n c e in e d itin g t h i s paper and th e i r h e lp fu l suggestions throughout the course of the program: Dr. Jay Savage, Dr. Gerald Bakus, and Dr. Paul Saunders. Dr. Donn Gorsline of the Geology Department was h e lp fu l in organizing the manuscript and in analyzing the hydrographic data. The follow ing members of the Department of Biology’s graduate student body were o f g reat a s sista n c e in the f i e l d work aspects o f t h i s study: Mr. Richard Anderson, Mr. Richard Casey, Mr. Michael Coffy, Mr. Robert Lavenberg, Mr. Richard McGinnis, Mr. Geoffrey Moser, and Mr. John Paxton. My a p p rec iatio n is extended to the o f f ic e r s and crew of the R/V VSLERO IV without whose help t h i s study would not have been p o ssib le . F in a lly , my thanks to Dr. J. Laurens Barnard who, while employed by th e Beaudette Foundation, offered much help in th e id e n tif ic a tio n o f c e rtain gammarid species throughout th e course of t h i s study. P a r t i a l support for t h i s work was furnished by th e N ational Science Foundation. The San Pedro Channel work and th e Outer Santa Barbara Passage work were supported by NSF (G-10691) and NSF (G-23467) re sp e c tiv e ly . TABLE OF C O M TENTS P age ACKNC NL E D G K E K T3 i i LIST CF TABLES........................................................................................... v i LIST 0 F ILLUSTRATIONS.......................................................................... x Chapter I . INTRODUCTION............................................................................ 1 O b je c tiv e s H is t o r ic a l Review Methods and M a te r ia ls D e sc r ip tio n o f Study Areas I I . THE KID-WATER AKPHIPOD FAUNA OF SOUTHERN CALIFORNIA WATERS...................................... 36 S p e c ie s A ccou nts, Outer Santa Barbara P assage Q u a lit a t iv e O b serv a tio n s on S ev era l S t a t io n s From th e Waters o f the San Pedro Channel A Comparison o f th e Outer Santa Barbara P assage and the San Pedro M a te r ia ls I I I . DISCUSSION................................................................................... 139 S p e c ie s C om position P o p u la tio n s i z e G eographical D is tr ib u t io n V e r tic a l D is t r ib u t io n and M igration R ep rod u ctive A c t iv i t y E c o lo g ic a l R e la tio n s h ip s I d e n t i f i c a t i o n o f L ocal Mid-Water Amphipoda IV. SUM M ARY.......................................................................................... 193 V e r t ic a l D is tr ib u tio n and M igration R ep rod u ctive A c t i v i t y i v TABLE OF CONTENTS— C o n tin u e d Page Comparison o f Study Areas Research O p p o r tu n itie s APPENDICES............................................................................................................ 197 v L IST OP TABLES T a b le P a g e 1 . Depth D is t r ib u t io n o f Day and N ig h t Samples Taken in th e Area o f th e O uter Santa Barbara P a ssa g e ............................................................................ 16 2 . I n te r p o la te d Data From CCOFI S ta tio n 9 0 .3 7 , I - 3 0 - 6 2 , 0900 h r s . , 33°10' N, 1 1 8 °2 3 .5 1 W , C ru ise 6 2 0 1 -2 ................................................ 22 3. I n te r p o la te d Data From CCOFI S ta tio n 9 0 .3 7 , 4 - 7 -6 2 , 0424 h r s ., 33°10' N, 118°23' W , C ru ise 6 2 0 3 -4 ................................................................................. 22 4. I n t e r p o la te d Data From CCOFI S ta tio n 9 0 .4 0 , 8 -2 9 -6 2 , 0631 h r s ., 3 3 °0 4 .5 ' N, 118°35 ' w, C r u ise 6 2 0 7 -8 .................... 23 5. I n t e r p o la t e d Data From CCOFI S ta tio n 9 0 .3 7 , I I - 2 - 6 2 , 0333 h r s ., 33°11' N, 1 1 8 °2 2 .5 ' W , C ru ise 6 2 1 0 -1 1 ........................................ 23 6. V a r ia tio n in Therm ocline Depth and I n t e n s i t y . . . . 26 7. V a r ia tio n in Mean Ten-M eter and S u rface Tem peratures................................................................................... 27 8. S ta t io n L i s t and Sam pling Data fo r R. n a t a t o r ........................................................................................ 37 9. P e r c e n ta g e s o f P o s i t i v e Samples fo r R. n a ta to r a t D if f e r e n t Depths During th e Day and N ig h t................................................................................. 38 10. S eason al Changes in S iz e Range and Numbers Per Trawl Hour fo r R. n a t a t o r ......................................... 39 11. S t a tio n L i s t and Sampling Data fo r F. C besus. . . . 40 12. S ta tio n L i s t and Sample Data fo r P. C oecu s............. 41 v i L IST OF TABLES— C o n tin u e d T a b le P a g e 13. Day and N igh t Depth D is tr ib u tio n f o r P a ra c a lllso m a c o e c u s Based on th e P er ce n ta g e s o f P o s i t i v e Sam ples...................................... 42 1 4 . S ta tio n L i s t and Sample Data for C yphocarls an on yx...................................................................... 44 15. S ta tio n L i s t and Sample Data fo r C yphocarls r ic h a r d i ................................................................. 50 16. V e r tic a l D is tr ib u t io n o f C yphocarls r ic h a r d i Determ ined by Day and N ig h t Sam ples.......................... 51 1 7 . S ta tio n L i s t and Sample Data fo r O rchom enella............... 56 1 8 . S ta tio n L i s t and Sample Data fo r P la t y s c e lu s s e r r a t u l u s .......................................................... 58 19. S ta tio n L i s t and Sample Data fo r Eupronoe m in u ta. ..................................................... 60 20. Day and N ight Depth D is tr ib u tio n o f Eupronoe m inuta b ased on th e P ercen ta g es o f P o s i t i v e Sam ples......................................................................... 61 21. S t a tio n L i s t and Sample Data fo r Primno macropa.............................................................................. 66 22. S ta tio n L i s t and Sample Data fo r C ystlsom a f a b r i c i i ...................... 71 23. S ta tio n L i s t and Sample Data fo r S t r e e t s i a p r o n o id e s ................................................................. 76 24. Day and N ig h t Depth D is tr ib u tio n o f S t r e e t s i a p ro n o id es Based on th e P er c e n ta g e s o f P o s i t i v e Sam ples......................................................................... 77 25. S ta tio n L i s t and Sample Data fo r H yperia s p i n i g e r a ...................................................................... 81 26. S ta tio n L i s t and Sample Data fo r H yperia b e n g a le n s is ................................................................. 83 v i i LIST OF TABLES— C o n tin u e d T a b le P age 27. S ta tio n L i s t and Sample Data fo r H yperia g a l b e ................................................................................. 87 28. Day and N ig h t Depth D is tr ib u t io n fo r H yperia g a lb a Based on th e P er ce n ta g e s o f P o s i t i v e Sam ples............................................... 89 29. S ta tio n L i s t and Sample Data fo r V i b i l l a arm ata.............................................................................. 93 30. Day and N ig h t Depth D is t r ib u t io n o f V i b i l i a armata Based on th e P er ce n ta g e s o f P o s i t i v e Sam ples........................................ 95 31. S ta tio n L i s t and Sample Data fo r V i b i l i a v i a t r i x ................................................................................................ 99 32. Day and Might Depth D is t r ib u t io n s fo r V i b i l i a v i a t r i x Based on th e P er ce n ta g e s o f P o s i t i v e Sam ples.................................................................. 101 33. S ta tio n L i s t and Sample Data fo r Phronima s e d e n t a r ia ................................................................. 105 34. Day and N igh t Depth D is t r ib u t io n s fo r Phronima s e d e n ta r ia Based on th e P ercen ta g es o f P o s i t i v e S a m p le s............................................................... 108 35. S ta tio n L i s t and Sample Data fo r Paraphronima g r a c i l u s ............................................................ 113 36. Day and N ig h t Records o f Number Per Trawl Hour and P er ce n ta g e s o f P o s i t i v e Samples fo r Paraphronima g r a c i lu s Taken in Sh allow and Deep H a u ls.......................................................... 115 37. S ta tio n L i s t and Sample Data fo r Paraphronima c r a s s l p e s .......................................................... 119 38. Day and N ig h t Depth D is tr ib u t io n o f Paraphronima c r a s s ip e s Based on th e P er ce n ta g e s o f P o s i t i v e Sam ples................................... 121 39. S ta tio n L i s t and Sample Data fo r S cin a t u l l b e r g i ............................................................................ 127 v i i i LIST OF TABLES— C o n tin u e d T a b le P age 4 0 . S ta tio n L i s t and Sample Data fo r S cin a b o r e a l i s ............... ......................................................... 128 4 1 . S ta tio n L i s t f o r Q u a lita t iv e Samples From th e San Pedro C hannel.............................................130 4 2 . S p e c ie s C om position Above and Below 50 M eters During th e W inter and th e Summer................145 i x L IST OF ILLUSTRATIONS F ig u r e P a g e 1 . Map Showing th e G eneral L o c a tio n s o f th e stu d y Areas o f f th e C a lif o r n ia C o a st........................ 19 2. Temperature P r o f i l e f o r January Drawn From • th e Data o f th e CCOFI S t a t i o n s ..................................... 25 3. Temperature P r o f i l e f o r A p ril Drawn From th e Data o f th e CCOFI S t a t i o n s ..................................... 25 4. Temperature P r o f i l e f o r August Drawn From th e Data o f th e CCOFI S t a t i o n s ..................................... 25 5. Temperature P r o f i l e f o r November Drawn From th e Data o f the CCOFI S t a t i o n s ..................................... 25 6. T e m p e r a tu r e -S a lin ity Diagram fo r January Drawn From th e Data o f th e CCOFI R e p o r ts 32 7. T e m p e r a tu r e -S a lin ity Diagram fo r A pril Drawn From th e Data o f th e CCOFI R e p o r ts 32 8. T e m p e r a tu r e -S a lin ity Diagram f o r August Drawn From th e Data o f th e CCOFI R ep orts 32 9. T e m p e r a tu r e -S a lin ity Diagram f o r November Drawn From th e Data o f th e CCOFI R ep o rts 32 10. Com posite T e m p e r a tu r e -S a lin ity Diagram o f A ll Four CCOFI S t a t i o n s ..................................................... 34 11. S ea so n a l V a r ia tio n in Mean S iz e and S iz e Range fo r C yphocarls anonyx..................................... 48 12. V a r ia tio n in Mean S iz e and S iz e Range fo r C yphocaris r i c h a r d i ............................................................... 53 13. V a r ia tio n in th e P e r ce n ta g e s o f Mature Fem ales C arrying Ova and Young Throughout th e Year (C yp hocaris r ic h a r d i ) .................................... 53 x LIST OF ILLUSTRATIONS— C o n tin u e d F igu re Page 1 4 . S ea so n a l V a r ia tio n in Mean S iz e and S iz e Range f o r Eupronoe m in u ta ................................................... 64 15. S eason al V a r ia tio n in th e P er ce n ta g e s o f Mature Fem ales o f E. m inuta C arrying Ova and Young ............ 64 1 6. S eason al V a r ia tio n in Mean S iz e and S iz e Range fo r Primno m acropa................................................... 69 1 7 . S eason al V a r ia tio n in th e P er ce n ta g e s o f Mature Fem ales o f P. macropa C arrying Ova and Young............................................... 69 ie. S eason al V a r ia tio n in Mean S iz e and S iz e Range fo r S t r e e t s i a p r o n o id e s ...................................... 79 19. S eason al V a r ia tio n in th e P er ce n ta g e s o f Mature Fem ales o f S. p ro n o id es C arrying Ova and Young T.................................................... 79 20. S eason al V a r ia tio n in Mean S iz e and S iz e Range fo r H yperia b e n g a le n s is ...................................... 86 21. S eason al V a r ia tio n in th e P e r ce n ta g e s o f Mature Fem ales o f H. b e n g a le n s is C arrying Ova and Young .................................................................... 86 22. S eason al V a r ia tio n in Mean S iz e and S iz e Range fo r H yperia g a lb a ..................................................... 91 2 3. S eason al V a r ia tio n in th e P e r ce n ta g e s o f Mature Fem ales o f H. g a lb a C arrying Ova and Young...................... 91 24. S eason al V a r ia tio n in Mean S iz e and S iz e Range f o r V i b i l i a arm ata................................................... 97 25. S eason al V a r ia tio n in th e P er c e n ta g e s o f I n d iv id u a ls C arrying Ova and Young......................... 97 26. S eason al V a r ia tio n in Mean S iz e and S iz e Range fo r V i b i l i a v l a t f l x ................................................ 103 x l LIST OF ILLUSTRATIONS— C o n tin u e d F igu re Page 27. Season al V a r ia tio n in th e P ercen ta g es o f I n d iv id u a ls C arrying Ova and Young......................... 103 28. Season al V a r ia tio n in Mean S iz e and S iz e Range f o r Phronima s e d e n t a r ia ...................................... I l l 29. S eason al V a r ia tio n in th e P er ce n ta g e s o f -Mature Females o f P. se d e n ta r ia C arrying Ova and Young....................................................... I l l 30. S eason al V a r ia tio n in Mean S iz e and S iz e Range f o r Paraphronima g r a c l l u s ................................. 117 31. S eason al V a r ia tio n in the P er ce n ta g e s o f Mature Females o f P. g r a c llu s Carrying Ova and Young.............................................................................. 117 32. S eason al V a r ia tio n in Mean S iz e and S iz e Range f o r Paraphronima c r a s s i p e s ............................ 123 33. S eason al V a r ia tio n in the P ercen ta g es o f Mature Females o f P. c r a s s ip e s C arrying Ova and Young............... .................................... 12 3 34. Season al V a r ia tio n in Number Per Trawl Hour f o r th e T otal Amphipod P o p u la tio n 142 35. Day and Might Depth D is t r ib u t io n o f R hachotropis n a ta to r Based on th e P e r ce n ta g e s o f P o s i t i v e Sam ples............................ 149 36. Day and Might Depth D is t r ib u tio n o f S t r e e t s i a p r o n o id es Based on th e P er ce n ta g e s o f P o s i t i v e Sam ples............................. 152 37. Day and M ight Depth D is tr ib u tio n o f Phronima s e d e n ta r la Based on th e P er ce n ta g e s o f P o s i t i v e Sam ples............................. 155 38. Day and Might Depth D is t r ib u tio n o f Hyperia galb a Based on th e P ercen ta g es o f P o s i t i v e Sam ples............................................................ 157 x i i LIST 0? ILLUSTRATIONS— C o n tin u e d F igu re Page 39. Day and N ight Depth D is tr ib u t io n o f V i b i l i a armata Based on th e P er ce n ta g e s o f P o s i t i v e Sam ples................................................................. 159 40. Day and N ight Depth D is tr ib u t io n o f V i b i l i a v i a t r i x Based on th e P ercen ta g es o f P o s i t i v e Sam p les................................................................. 162 41. Day and N ight Depth D is tr ib u t io n o f Eupronoe m inuta Based on th e P ercen ta g es o f P o s i t i v e Sam p les................................................................. 165 42. V a r ia tio n in th e P er ce n ta g e s o f th e T otal Amphipod Female P o p u la tio n C arrying Cva and Young Throughout th e Y ear............................... 178 43. Season al Record o f the Number o f S p e c ie s Showing H ig h est P er ce n ta g e s o f Females w ith Cva and Young...................................................... 181 x i i i CHAPTER I INTRODUCTION O bjectives A s e rie s of c ru ise s of the R/V VELERO IV to the waters o f f the coast o f southern C a lifo rn ia have revealed large q u a n titie s of mid-water organisms. A sampling p ro gram using an Issacs-K idd Mid-water Trawl (Issa c s and Kidd, 1953) was conducted in the w aters of the Outer Santa Barbara Passage, in the area of the Santa C atalina Basin, and in th e w aters of the San Pedro Channel, in the area of the San Pedro Basin. The concern of t h i s d is s e r ta tio n was to examine the amphipod crustaceans of the co llected m a te r ia l. The purposes of t h i s study were: (l) to determine the c o n s titu e n ts of the mid-water amphipod fauna of the lo c a l s h e lf w aters, (2) to examine the v e r t i c a l d i s t r i b u t io n a l and v e r t i c a l m ig ratio n al p a tte r n s of those species which were abundant enough to perm it such in v e s tig a tio n s , (3) to obtain as much inform ation as p o ssib le regarding the reproductive cycles of the abundant species, ( 4 ) to determine seasonal flu c tu a tio n s in the abundance and h a b its of the dominant species and, ($) to examine the general 1 2 hydrographic co n d itio n s of th e study areas and r e l a t e th i s inform ation to the ecology of the amphipods. An attem pt was made to sample the Outer Santa Barbara Passage at various depths, during d if f e r e n t times of the day and n ig h t, throughout the year. A t o t a l of e ig h ty -th re e samples were used from the Santa Barbara Passage m a te ria l. Sixteen samples from the San Pedro Channel area were employed fo r comparative purposes. The Outer Santa Barbara Passage samples were taken during monthly c ru ise s from July 1962 to A p ril 1964. C ollection dates fo r the San Pedro m a te ria l are ir r e g u la r and range from December i 960 to A pril 1963. A ll of the c o lle c tio n s considered in t h i s study were obtained through the use of the R/V VELERO IV of the Allan Hancock Foundation of th e U niversity of Southern C a lifo rn ia . Discussed in t h i s paper are nineteen species of the Suborder Hyperiidea and six species of the Suborder Gammaridea. Other organisms which have been c o lle c te d on t h i s p r o je c t and which are now under in v e s tig a tio n a t the Allan Hancock Foundation are mid-water f is h e s , cephalopods, ostraco d s, euphausids, mysids, and n a ta n t decapods. H is to r ic a l Review Early d e s c r ip tiv e re p o rts Near the beginning of the century a number o f major works became a v a ila b le describing the amphipod faunas in various p a r ts of the world. These re p o rts were often a sso cia ted with the in v e s tig a tio n s of extended c o lle c tin g ex p ed itio n s. Although most of these e a rly works were d e s c rip tiv e , considerable inform ation regarding the d i s t r i bution, zo n a tio n , and reproductive a c t i v i t y was noted. Several of these early papers have proven indispensable in the id e n tif ic a tio n of the specimens c o lle c te d in t h i s present study. P u b lic a tio n s such as B ate’ s catalogue of B ritis h Museum amphipods (1862), Stebbing’ s e x c e lle n t re p o rt on the amphipods from the CHALLENGER expedition (1888), B o v alliu s' complete review of the oxycephalids (1890), S tebbing’s ”Das T e rre ich ” on the Gammaridea (1906), Holmes’ re p o rt on the ALBATROSS cru ise s o ff the P a c ific coast o f North America (1908), Stephensen’ s works on the amphipods of the Danish Oceanographic E xpeditions (1918, 1923, 1924, and 192$), and P i r l o t ' s review o f the amphipods of the ARM AUER HANSEN c ru ise s (1929) are in d ic a tiv e of the type of stu d ies which provided much help on the s p e c ific i d e n tif ic a tio n of lo c a l forms. The main concern o f t h i s p resen t study was the n a tu ra l h is to ry of the amphipod fauna. There e x is t few works which o ffe r complete inform ation regarding the reproductive a c tiv i ty or v e r t i c a l m igratory a c t i v i t y fo r many species. V e rtic a l d is tr ib u tio n and m igration V e rtic a l m igration in planktonic and p elagic organisms has been known since the days of the CHALLENGER ex p ed itio n s. Stebbing (1&83) suggested th a t c e rta in forms m igrate upwards from a depth of two hundred meters during the day, nearing the surface at n ig h t. This a c tiv i ty of n ig h tly r is in g and d a ily sinking has become known as d iu rn a l, v e r t i c a l m ig ratio n . The f a c to rs involved in re g u la tin g v e r t i c a l m igration have b,een the object of much study since the phenomenon was f i r s t observed. Peres and Deveze (1963) and Raymont (1963) reviewed the problems of v e r t i c a l d is trib u tio n and m igration and the fa c to rs involved. Light was immediately recognized as an extremely im portant parameter in flu en cin g m igratory a c t i v i t y of planktonic and p elagic organisms. Most of the e a rly works were centered around the p h o to s e n s itiv ity of m igrating organisms and th e i r re a c tio n s to v a r ia tio n s in lig h t in te n s ity . I t was soon discovered th a t v e r t i c a l movement of some organisms took place a t much g re a te r depths than had been suspected. E ste rly (1912) showed th a t c e rta in copepods ( e .g ., Calanus) m igrated from depths of four hun dred m eters to the su rface. Murray and H jort (1912) demon s tr a te d th a t many planktonic forms which resid e d a t depths of up to eig h t hundred m eters move upwards during the n ig h t. The question then arose regarding the depth of lig h t p e n e tra tio n in the sea and the a b i l i t y o f the deeper liv in g organisms to perceive very dim lig h t . Through the use of photographic p la te s Murray and H jort showed th a t an appreciable amount of lig h t p en e trate d to depths of more than fiv e hundred meters and th a t some lig h t reached depths of one thousand m eters. Recent stu d ie s involving the bathyscaph ex p lo ratio n s in d ic a te th a t the la s t measurable lig h t e x is ts at about six hundred ten m eters. The fa c to rs in flu en c in g v e r t i c a l movement below these above-suggested depths are subject to continuous specu latio n . As v e r t i c a l m igrations in a d d itio n a l organisms became apparent, f a c to rs o ther than lig h t were re a liz e d to be im portant. Clarke (1933) demonstrated th a t the copepod M etridia would not pass through the therm ocline while m igrating upwards a t n ig h t. The temperature b a r r ie r p ro vided by the therm ocline was found to be a lim itin g f a c to r in the v e r t i c a l movement of many amphipod sp ecies. Other hydrographic s itu a tio n s such as oxygen minimum zones and h a lo clin e s may be involved but data are, in most cases, i n s u f f ic ie n t to su b s ta n tia te any i n f l u e n t i a l aspects of these f a c to rs . The discovery and in v e s tig a tio n s of the so -c a lle d deep s c a tte rin g la y ers have been reviewed by Dietz (1962). S tudies with echo soundings on th ese la y e rs have given a g reat deal of in s ig h t in to the v e r t i c a l zonation and movement o f many p elag ic forms. Dietz suggested th a t lig h t and tem perature are the primary fa c to rs involved in v e r t i cal m igrations and th a t th e re are c e rta in advantages to such movements. Organisms found w ithin the s u n lit la y ers of the sea during the day are provided w ith l i t t l e or no concealment from p re d a to rs. D ietz suggests th a t by ’’h id in g ” in the dark, deeper w aters during times of lig h t p e n e tra tio n the organisms escape predation to a large ex ten t. The most widely accepted advantage to r is in g dur ing the dark hours is th a t t h i s a c t i v i t y brings organisms in to a region of abundance of phytoplankton and zooplankton upon which they may feed. This feeding a c t i v i t y may not be the reason fo r m igration, but i t i s c e rta in ly an advantage. Dietz l i s t s the major c o n s titu e n ts of the deep s c a tte rin g layers as being myctophids (la n te rn f i s h e s ) , and euphausid and s e rg e s tid shrimps. These organisms may be taken a t the surface during very dark n ig h ts . Normally descent begins ju s t before dawn, when in d ir e c t lig h t from the r i s i n g sun f i r s t becomes apparent. On m oonlit n ig h ts, however, m igrating forms may never reach the surface or may begin t h e i r descent e a rly . Off the C a lifo rn ia coast, according to D ietz, there are th re e deep s c a tte rin g la y e rs. During the daylight hours these lay ers were found a t approximately 2$ 5 , ^ 2 0 , 7 and 515 m eters. From echo soundings i t appeared th a t th e se lay ers did not cross each o ther but remained separate and d i s t i n c t throughout the course of t h e i r v e r t i c a l movements. Apparently each group of organisms is adjusted to d i f f e r ent, and p a r tic u la r , lig h t i n t e n s i t i e s . Aron (1962), who conducted stu d ie s in the E astern North P a c ific , in d icated th a t th ere were g reat co ncentrations of animals a t depths ranging from th re e hundred to e ig h t hundred m eters during the day which moved towards the surface a t n ig h t. Aron suggested th a t s a l i n i t y was im portant as a b a r r i e r to m igrating forms where th e re was a strong h a lo c lin e , such as the convergence of interm ediate P a c ific water with Subarctic water. From a n a ly sis of depth records reported in ea rly works one can surmise th a t most of the hy p eriid amphipods are m ig rato rs. The p rec ise d i s t r i b u t i o n a l p a tte r n s , how ever, have been described fo r only a few species. P re sented here are general reviews of some o f the more s i g n i f ic a n t stu d ies which concerned v e r t i c a l movements in amphipods. Mackintosh (1938) rep o rted on the d iu rn a l p a tte r n s of se v eral crustaceans. Included in th a t study was i n f o r mation on Primno macropa, a species also taken in t h i s present work. A comparison o f the r e s u lt s o f Mackintosh with those of the present study i s made l a t e r but some remarks are a p p ro p riate a t t h i s p o in t. The samples discussed by Mackintosh were taken with a one-meter plank ton n e t. These samples were p rim arily c o lle c te d in oblique tows from one hundred meters to the su rface. Although the r e s u l t s of th a t work did show v e r t i c a l movement in many of the organisms stu d ie d , including P. macropa, such a sam p lin g technique can only show m igrations in the upper le v e ls and depends upon speculation as to the lower depth lim its of the popu latio n s. That study, th e re fo re , may not have revealed the e n tir e p ic tu re o f what was a c tu a lly tak in g place. I t should be mentioned th a t M ackintosh’s suggestion th a t P. macropa m igrates to the surface during the day and goes deeper at night i s co n trad icted by the r e s u l t s of t h i s p rese n t work. The suggested m igratory p a tte r n may take place in the A n tarctic waters where Mackintosh worked but c e rta in ly does not occur o ff the coast of southern C a lifo rn ia . A noteworthy study was conducted by Waterman e t a l . (1939) o ff Cape May, New Je rse y , using h o riz o n ta lly towed two-meter plankton n e ts . C o llectio n s were made a t a sin g le s ta tio n fo r a five-day period. Two species of amphipods were taken in s u f f ic ie n t numbers to form ulate s ig n ific a n t p a tte rn s of d iu rn a l m igration. One of th ese sp ecies, a p elag ic gammarid Cyphocaris anonyx. was also c o lle c te d d u r ing t h i s p resen t study. The r e s u l t s of Waterman regarding 9 ■ th a t species are discussed in a l a t e r se c tio n . V ib ilia propinqua, also taken by Waterman, was not c o lle c te d in t h i s study but two o th er species of th a t genus were found (V ib ilia armata and V. v i a t r i x ) . The v e r t i c a l movement of amphipods may be regarded as a tw enty-four hour exogenous rhythm. The d is tin c tio n between exogenous and endogenous rhythms, as s ta te d by Harker (195&), i s based upon whether or not the rhythm p e r s i s t s when environmental v a ria b le s are held constant. Although few data are a v a ila b le to support the suggestion th a t amphipod m igrations are exogenous, i t i s most lo g ic a l to assume th is to be the case. Considering th a t lig h t is an important f a c to r in the re g u la tio n of v e r t i c a l movement, one would suspect th a t in constant lig h t conditions the re g u la r d iu rn a l m igrations would cease. This is supported in some organisms, as mentioned e a r l i e r , where the presence of moonlight d is ru p ts th^e normal m igratory p a tte rn and causes e a rly descent before dawn. Reproductive a c t i v i t y Complete inform ation on the reproductive cycles of amphipods is scarce. Some comparative inform ation can be obtained from the various expedition re p o rts in which the presence and absence of ova and young were recorded. Bigelow (1926) reviewed much of the known reproductive inform ation on th e Hyperiidea and made some generalizations. 10 He suggested th a t most of the hyperiids reproduce throughout la te spring and e a rly summer. Young were noted to be abundant during these periods in the upper twenty- fiv e meters of w ater. From his work o ff the coast of Maine, Bigelow suggested th a t the t o t a l zooplankton popula tio n is minimal in about l a te February or March, r is in g in A pril to a maximum in June. Bigelow's r e s u l t s c o r r e la te , in p a rt, with the fin d in g s of t h i s present study. This c o rre la tio n is discussed in a l a t e r sectio n . Dunbar (1946) studied Themisto l i b e l l u l a in A rctic w aters and noted th a t the breeding period occurred from March to July. Although T. l i b e l l u l a was not c o lle c te d during t h i s p resen t study, Dunbar's work is mentioned because i t re p re se n ts one of the few complete works on the reproductive a c t i v i t y for an amphipod species. Recent stu d ies in lo c a l waters The most recen t works on the mid-water gammarids from southern C a lifo rn ia w aters are those of Barnard (1954) and Hurley (1963). Barnard reported on four species of bathypelagic gammarids. Although h is paper was p rim arily d e s c rip tiv e in n atu re, c e rta in v e r t i c a l d i s t r ib u t io n a l inform ation was obtained by referen ce to capture times and depths fo r the d if fe r e n t sp ecies. H u rley 's paper d e a lt with the fam ily Lysianassidae from the west coast of North and C entral America. His work was of some help in the i d e n tif ic a tio n of c e rta in species. 11 Hurley (1956) o ffe rs the most recen t study of the lo c a l mid-water h y p e riid s. He studied c o lle c tio n s made from the VELERO IV in lo c a l w aters using various sampling methods other than the Issacs-K idd Mid-water Trawl. In most cases a much sm aller number of specimens were c o l le c te d by Hurley than were taken in t h i s present study. Some inform ation was presented regarding v e r t i c a l d i s t r i bution and some suggestions were made of general m igratory p a tte r n s . H urley's data were based p rim arily on daytime tows. Accurate v e r t i c a l m igratory p a tte r n s cannot be deduced from th ese data. This b r ie f review by no means considers a l l of the l i t e r a t u r e on the various aspects of the biology of mid water amphipods. Accompanying each species the reader w ill find a l i s t of se le c ted re fe ren c e s. Methods and M aterials Sampling gear and i t s use A te n -fo o t Issacs-K idd Mid-water Trawl (IKMWT) was employed as a sampling device in the c o lle c tio n of a l l of the m a te ria l used in th is study. The traw l has an ap e rtu re of one hundred square f e e t (approximately 9 . 2$ m ) and is approximately f i f t y - f i v e f e e t in length when f u lly assem bled. The mouth of the traw l i s f i t t e d with a heavy spreader bar and a s ta b ili z in g paravane. These two s tr u c tu re s function in keeping th e mouth of the net open while 12 fis h in g and in forcing the net down by adding weight. The paravane p a r t i a l l y prevents excessive flu c tu a tio n s in fis h in g depth. The main portion of the net is composed of an inner l / 4 -inch mesh with an o u te r, heavy layer fo r stren g th to prevent te a rin g . The cod end of the traw l i s f i t t e d with a plankton net in which the sample i s re ta in e d . A few samples were taken using a Foxton opening and closing device. Only two of these samples provided s i g n i f ic an t inform ation. These two samples are given sp e c ia l consideration in the d iscu ssio n . The Foxton device not only takes a separate sample a t a prescrib ed fish in g depth but has the added value of r e ta in in g , s e p a ra te ly , the m a te ria l c o lle c te d as the traw l i s being lowered and ra ise d . Thus i t was p o ssib le to make comparisons of the. m a te ria l a t fish in g depth with the specimens taken from shallower water a t the same s ta tio n . This comparison was very im portant in the v e r t i c a l d is t r i b u t i o n a l and v e r t i c a l m ig ratio n al asp ects o f the study. H orizontal tows were taken in the two sampling areas a t various depths and at d if f e r e n t times of the day and n ig h t. Most of the traw ls were conducted fo r a period of two hours a t depth a t an approximate v e lo c ity of four knots. The fis h in g time was reduced in some of the shallow tra w ls due to the la rg e numbers of salps taken in the sam p le s . These organisms tended to pack t i g h t l y in the cod 13 end of the n et and o ften destroyed o th er specimens. Some of the very deep traw ls were fish ed fo r longer periods of time than th e standard two hours. Due to the g reat lengths of time n e c e ss a rily expended in lowering and ra is in g the net to and from increased fish in g depths, a more e f f i c i e n t program was m aintained by in c re asin g the fish in g time once the gear was a t depth. Sample depths were determined by two methods. In some cases a p ressu re gauge was used and in o thers the depth was determined by tr ia n g u la tio n . A comparison of these two methods on the same traw l revealed sim ilar measurements. The depths recorded in t h i s paper are the best estim ates of the a c tu a l fis h in g depth. These e s t i mates may be in some erro r fo r the follow ing reasons: 1. The p ressu re gauges used in t h i s study record only the deepest point to which the traw l descends. 2. Regardless of the accuracy of the recorded fis h in g depths, i t must be remembered th a t the traw l fis h e s as i t i s being ra is e d and lowered; thus, except when using the Foxton device, th ere was always contamination from shallower depths. 3. I t i s the opinion of t h i s author and o ther workers (Aron et a l . , 1964) th a t the IKM W T v a rie s i t s fis h in g depth to some e x ten t. This v a r ia tio n i s suspected to be e s p e c ia lly great when the s h ip ’s speed i s being a lte r e d . Changes in s h i p ’s speed take place ju s t a f t e r the traw l reaches depth and ju s t p rio r to i t s r e t r i e v a l from depth. The p a r t i a l l y successful use of the Foxton closing device, as described e a r l i e r , made i t possible to determine, in some cases, the degree of contam ination. Q u a n tita tiv e samples Upon r e tr ie v in g the tra w l, the samples were placed immediately into a large tub of sea water. P ortions of the bulk sample were tra n s fe rre d to so rtin g tra y s and a rough so rtin g of the e n tire sample was conducted. All of the fis h e s , cephalopods, and la rg e r crustaceans were sorted from the bulk sample. The resid u e u su a lly amounted to about one gallon o f m a te ria l from which a p in t a liq u o t was taken for d e ta ile d so rtin g of the amphipods. A ll of the amphipods were removed from each p in t sample and placed in 70 per cent alco h o l. Amphipods from each s ta tio n were counted, measured, and t h e i r sex determined when p o ssib le. N otations concerning reproductive condition were made during the so rtin g and counting process. A liquoting o f the bulk sample was necessary due to the large numbers o f amphipods o ften p resen t in the 15 catches. Although t h i s method gave only approximate q u a n tita tiv e data, the r e s u l t s showed a c o rre la tio n with the general observations made on board ship regarding changes in r e l a t i v e population d e n s itie s o f the various common species. For each species a record was made of the t o t a l number of in d iv id u als taken from each p in t a liq u o t. The d e n s itie s of the abundant species were expressed in the number per hour traw ling time. Since the resid u es amounted to about one g allo n , c a lc u la tio n s were made using the follow ing formula: # in d iv id u a ls /p in t x £ ( p i n t s / g a l .) # /traw l h o u r s ~ — 77 //hours a t depth Such values are only approximate but do r e f l e c t the population d e n s itie s a ccu rate ly enough to permit c e rta in sample comparisons. Q u a lita tiv e samples Near the end of th e sampling program several q u a lita tiv e samples were taken and analyzed. These mate r i a l s were used to determine the presence or absence and r e l a t i v e abundance of amphipod species a t tim es and depths th a t had not previously been represented in the sampling program. The m a te ria l from the San Pedro Channel was tr e a te d in t h i s q u a l ita tiv e manner. Sampling program Appendices I and I I l i s t the s ta tio n s which were used in t h i s study. Given th e re are the complete data fo r each sample. Table 1 is a record of the night and day hauls at various depths taken in the Outer Santa Barbara Passage. TABLE 1.---Depth d is t r ib u t io n of day and night samples taken in the area of the Outer Santa Barbara Passage Depth Number of Number of Total T otal Range in Q u a n tita tiv e Q u a lita tiv e Number Q u a n tita tiv e Meters Samples Samples Samples Hours Night 0- 50 2 2 4 3 5 0- 100 2 0 2 4 1 0 0- 200 5 2 7 10 2 0 0- 300 3 1 4 6 3 0 0- 1+00 4 2 6 B 4 0 0- 500 2 0 2 4 500- 600 4 3 7 B 600- 700 2 0 2 4 700- BOO 1 0 1 2 BOO- 900 0 1 1 0 9 0 0 -1 1 0 0 1 2 3 3 Day 0 - 50 0 2 2 0 50- 100 0 2 2 0 1 0 0- 200 0 2 2 0 2 0 0- 300 3 1 4 4 3 0 0- 400 3 1 4 6 4 0 0- 500 4 1 5 B 5 0 0- 600 5 0 5 9 6 0 0- 700 3 1 4 6 7 0 0- BO O 3 0 3 6 B0 0- 900 4 0 4 B 9 0 0- 1100 7 1 8 16 17 Those traw ls whose midpoints were between 1800 and 0600 hours were regarded as night samples. Those traw ls whose m idpoints were between 0600 and 1800 hours were regarded as daytime samples. Observations on liv in g organisms In ad d itio n to the work on preserved m a te ria l, some observations were made on liv in g amphipods immediately a f t e r t h e i r removal from the net. S p a tia l o rie n ta tio n and swimming behavior were noted for sev eral species which were commonly taken a liv e . D escription o f the Study Areas The c o n tin en tal sh e lf o ff the coast of southern C a lifo rn ia i s a complex system of basins, troughs, and isla n d s. I t has been termed a c o n tin en tal borderland by Shepard and Emery (1941) due to the s tr ik in g d iffe re n c e s between i t s topography and th a t of normal sh e lf area s. Emery (I960) o f fe rs a d e ta ile d d e sc rip tio n of the various regions of the southern C a lifo rn ia c o n tin e n ta l borderland. P late I shows the lo c atio n of the San Pedro Channel and the Outer Santa Barbara Passage. The San Pedro Basin l i e s between th e mainland and Santa C atalina Isla n d , and the Santa C atalina Basin i s lo cated seaward of th e isla n d . These basins follow th e reg io n a l s t r u c t u r a l tren d s and are o rien ted p a r a l l e l to the c o a s tlin e in a northwest to south e a st manner. S i l l s a re located e i th e r a t the northw est or Figure 1 . —Map showing the general lo c a tio n of the study areas o f f the C a lifo rn ia coast. The four CCOFI s ta tio n s used in the oceanographic a n a ly sis are in d ic a te d by the months during which they were occupied. 18 PLATE I Palos Verdes,Calif. San Pedro Channel kSanta < Catalina .Nov Jan. .Apr ye •Aug 33 n San Clemente Is. lOmi. 20 the southeast ends of the b asin s. The depth of the lowest of the two San Pedro Basin s i l l s i s 730 meters and the depth of the lowest o f the two Santa C atalina Basin s i l l s i s 1030 m eters. The depth of the basin flo o r fo r San Pedro i s 966 meters and for Santa C atalina i s 1436 m eters. C ertain hydrographic readings were u til iz e d in determ ining the e f f e c ts of oceanographic conditions on the species composition, v e r t i c a l d i s t r ib u t io n , and m igratory p a tte rn s of the amphipods. Seasonal data on the conditions in the w aters over the Santa C atalina Basin were obtained through the use o f four re p o rts by the C a lifo rn ia Coopera t i v e F is h e rie s In v e s tig a tio n s (CCOFI). These four s ta tio n s were occupied in 1962 in the months o f January, A p ril, August, and November and o ffe r a general record of the seasonal flu c tu a tio n s in hydrographic conditions. The lo c a tio n s of the four CCOFI s ta tio n s are in d ic ated on P la te I by the ab b rev iatio n s of the months during which they were occupied. In a d d itio n to the CCOFI re p o rts sev eral bathythermograph readings were taken from the VELERO IV during tim es of b io lo g ic a l c o lle c tin g . These measurements were used in determ ining the therm ocline depth and in te n s i t y a t tim es of b io lo g ic a l work throughout th e year. The data presented here concerning th e w aters of the Outer Santa Barbara Passage are ty p ic a l fo r th e surface 21 waters over most of the southern C a lifo rn ia c o n tin e n tal borderland. Seasonal f lu c tu a tio n s for both study areas are sim ilar in both time and magnitude. The p ro p e r tie s of the basin w aters below s i l l depth fo r the two areas d i f f e r l i t t l e and are co n tro lle d by s i l l depth. The following inform ation is from Emery (I960). T°C S a lin ity °/oo O2 m l/l San Pedro Basin 5.06 34.29 0.2 Santa C atalina Basin 4*02 34-42 0.4 The s im ila r ity in basin w aters and the s im ila r ity in seasonal f lu c tu a tio n s throughout the study areas permit s ta tin g th a t the data co lle c te d from the Outer Santa Barbara Passage i s ty p ic a l of the hydrographic conditions fo r both study regions. The in te rp o la te d data from the four CCOFI re p o rts are presented in Tables 2-5 along with the d ate, time, and p o sitio n of each s ta tio n . P la te I I , Figures 2-5, a re the tem perature p r o f il e s drawn from the data presented in Tables 2-5. These curves i l l u s t r a t e the general f lu c tu a tio n s in th e tem perature s t r a t i f i c a t i o n of the surface w aters throughout the year. From these readings and measurements from bathythermograph c a s ts , Table 6 was constructed to i l l u s t r a t e the v a r ia tio n in therm ocline depth and in te n s it y based on th e change in tem perature in the top fo rty m eters of th e surface water. 22 TABLE 2 . —In te rp o la te d data from CCOFI s ta tio n 90.37, 1-30-62, 0900 h r s . , 33°10.5r N, 11802 3 .5 ’ W, Cruise 6201-2. Depth in Meters T°C S a lin ity °/oo 02 ml/1 0 14.14 33.54 5.90 10 14.03 33.54 5.79 20 13.39 33.52 5.64 30 13.71 33.52 5.41 50 12.98 33.52 4.83 75 11.42 33.64 3.75 100 11.14 33.83 2 .5 6 125 1 0 .5 0 33.90 2 . 56 150 10.01 34.05 2.08 200 9-41 34.09 1.89 250 8.39 34.11 1.79 300 7-87 34.16 1.31 400 7.32 34.24 0.75 500 6.34 34.32 0.31 TABLE 3 -—In te rp o la te d data from CCOFI s ta tio n 90.37, 4-7-62, 0424 h r s . , 33°10f N, ll8 ° 2 3 r W , Cruise 6203-4. Depth in Meters T°C S a lin ity °/oo 02 m l/l 0 14-14 33.56 6 .4 6 10 14.11 33.56 6 .4 8 20 12.08 33.58 5.18 30 11.72 33.60 4.76 50 1 0 .5 0 33.71 3.24 75 9.81 33.81 3.00 100 9.60 33.98 2.31 125 9.31 34.06 2.02 150 8.98 34.12 1.80 200 8.70 34.25 1.07 250 8 .4 6 34.31 0.77 300 7.91 34.29 0.71 400 6.78 34.30 0.44 500 6.28 34.33 0.31 600 5.69 34.37 0.23 23 TABLE 4*—In te rp o la te d data from CCOFI s ta tio n 90.40, $-29-62, 0631 h r s . , 33°04.5’ N, 11$°35’ W, Cruise 6207-$. Depth in Meters T°C S a lin ity °/oo r — 1 i — 1 E cv o 0 2 0 .$$ 33.$5 5.06 10 20.14 33.$2 5.3$ 20 1 6 .5 0 33.71 5.53 30 1 4 .1 2 33.6$ 5.57 50 1 1 . 6$ 33.70 4 . 66 75 9.91 33.$2 2 .9 2 100 9.2$ 33-92 2 .6 0 125 9 .0 0 33.96 2.44 150 $.72 34.02 2.40 200 7.94 34.05 1 .6 0 250 7.63 34.09 1.59 TABLE 5 •--In te r p o la te d data 11-2-62, 0333 h r . , 3 3 ° l l f N from CCOFI s ta tio n 90.37, , 11$°22.5 ' W, Cruise 6210-11. Depth in Meters T°C S a lin ity °/oo 0 2 m l/l 0 16.$5 33.6$ 5.63 10 1 6 .7 2 33.67 5.71 20 14.30 33.5$ 5.3$ 30 1 3 .0 0 33-54 5 .1 2 50 11.17 33.57 4.6$ 75 1 0 .2 2 33.66 3.$4 100 9 .6 2 33.$3 2.99 125 9 .2 2 33.97 2.59 150 9.11 34.06 2.30 200 $ .$ 0 34.16 1.69 250 $ .2 2 34.19 1.34 300 7.79 34.25 0.92 400 7.29 34.30 0.51 500 6.39 34.33 0 .2 6 Figures 2 - 5 .—Temperature p r o f il e s drawn from the data of the CCOFI s ta tio n s . P lo tte d are tem perature in degrees Centigrade a g a in st depth in m eters. 24 PLATE II 20 25 Dm 100- D m 100- 200- 200 - 300- 300 - 400 - 400 - 500- 500 - Jan. 3 2 Apr, 20 25 Dm Dm 100 - 200 - 200- 300- 300 - 400 - 400-1 500 - 4 5 Nov, 26 TABLE 6 . —V ariation in therm ocline depth and in te n s it y Month Depth of Thermocline Midpoint Change in T°C in Top 40 m January absent le s s than 1 February absent le s s than 1 March 20 m 3 A pril 15 m 3 May 25 m 4.5 June 20 m 5 July no data no data August IS m S .3 September 27 m 5-1 October 25 m 4 November 25 m 5-3 December (midpoint in d is tin g u is h a b le ) 1.3 Table 7 p rese n ts data taken from the CCOFI A tlas #1. Given here are mean ten-m eter tem perature values for a te n - year period (1950-1959) in the waters of the Outer Santa Barbara Passage (CCOFI S tatio n 90.37). The surface temper a tu re s are from a few measurements taken from th e VELERO IV during tim es o f b io lo g ic a l c o lle c tin g . I t can be seen from the temperature data presented in Tables 6 and 7 th a t th e re i s g reat seasonal v a ria tio n in the water above one hundred m eters. Solar h eatin g during the summer months ra is e s the tem perature of the surface waters se v e ral degrees. This in crease in surface tempera tu re has a d ir e c t e ffe c t on the depth and magnitude of the therm ocline. By comparing the surface tem perature v a r i a tio n s with the changes in ten-m eter tem peratures, i t can be seen th a t the e f fe c ts of so la r heating are sim ila r a t those two depths. P late I I , Figures 2-5, shows the cool surface w aters in the w inter with no d i s t i n c t therm ocline, the development of a weak therm ocline in the sp rin g , a g re a t r i s e in surface tem perature by August with the appearance of a strong therm ocline, and f in a ll y a drop in surface tem perature in November although the surface waters s t i l l re ta in e d enough heat to produce a s u b s ta n tia l therm ocline. TABLE 7 . —V ariation in mean ten-m eter and surface tem peratures Month Mean 10-meter T°C (1950-59) Surface' T°C (1962-63) January 14.35 1 4 .0 0 February 14.13 1 3 . SO March 1 4 .1 0 14.50 A pril 14.73 14.00 May 15.55 17.50 June 16.57 IS. 00 July IS. 19 1 9 .0 0 August 19.33 2 1 .0 0 September 19.37 2 1 .1 0 October IS. 14 2 0 .1 0 November 17.04 16.55 December 1 5 . SS 1 5 .0 0 Although the values presented in Table 7 fo r thermocline depth and in te n s it y are approximate, and are based on few o b serv atio n s, they do o ffe r a g en eral compar ison of those f a c to rs . I t can be seen th a t from March through November the depth of the therm ocline was r a th e r 28 constant while in December, January, and February the therm ocline was absent or very weak. The g re a te s t tempera tu re g rad ien ts in the top fo rty m eters of th e surface w aters were noted in la te summer. This corresponds to the r i s e in surface tem peratures during th i s period. From a n a ly sis of the CCOFI data i t can be seen th a t a r i s e in surface s a l i n i t y was apparent in August and November, corresponding to a r i s e in surface tem peratures a t those tim es. A permanent h a lo c lin e was p resen t during 1962 a t depths ranging from f i f t y to one hundred m eters. I t s magnitude was g r e a te s t in the w inter and spring months when surface tem peratures and s a l i n i t i e s were lowest. There was l i t t l e seasonal v a ria tio n in oxygen concentration as in d ic a ted by the measurements in the CCOFI re p o rts . With in c re a sin g depth th ere was a rapid decrease in the oxygen content to q u a n titie s of le ss than 0 .5 m l / l i t e r a t about fiv e hundred m eters. There was a decrease in the amount of oxygen a t shallow depths in the August records r e f le c tin g the high surface tem peratures during th a t month. The id e n t i f i c a t i o n of water masses o ff the coast of southern C a lifo rn ia i s d i f f i c u l t due to the g re a t amount of mixing and the formation of complex eddy systems by the C a lifo rn ia Current as i t moves southward along the coast. Emery (I960) presented a d e s c rip tio n of the cu rren t system 29 of th e lo c a l s h e lf w aters. As th e C a lifo rn ia Current flows p a s t Point Conception a larg e , counter-clockw ise eddy, or co u n tercu rre n t, i s formed east of the main surface cu rren t. To the ea st of the eddy most of the water resumes a so u th e a sterly flow and follows the c o a stlin e to Mexico. Below the main surface w ater mass there i s a layer of interm ediate water apparently of southern o rig in (Sverdrup, Johnson, and Fleming, 1941). Smery suggested t h a t a zone of mixing between th e northern water of the C a lifo rn ia Current and the deeper southern water e x is ts in a depth range of from two hundred to th re e hundred m eters. The percentages of southern and northern waters in t h i s zone of mixing flu c tu a te seasonally. There appears to be an in tru s io n of southern water in to shallower depths during the summer months. I t i s water o f southern o rig in th a t i s found in the lo c a l b asin s below s i l l depth. Reid (1962) presented measurements on what i s termed the C a lifo rn ia C ountercurrent. Immediately seaward of the one thousand fathom contour th e re e x is ts a northward flow of water a t a depth of two hundred f i f t y m eters; th is i s the C a lifo rn ia C ountercurrent. The cu rren t extends seaward for about fo rty m iles and moves northward at a maximum speed of .44 knots. Beyond the two thousand fathom contour (one hundred to one hundred tw enty-five m iles offshore) the flow of w ater a t two hundred f i f t y meters is in a n o rth e a s te rly d ire c tio n . Between the one thousand and two 3 0 * thousand fathom contours is found a so u th e aste rly flow a t two hundred f i f t y m eters. At the two thousand meter contour, where the n o rth e a s te rly and so u th e a ste rly flows meet, th e re are in d ic a tio n s of the tu rn in g of the n o rth e rly current into the southerly c u rren t. The data presented by Emery (I960) and by Reid (1962) in d ic a te the extreme com p le x ity of the cu rren ts over the c o n tin e n ta l borderland of C a lifo rn ia . P la te I I I , Figures 6-9, shows te m p e ra tu re -s a lin ity (T-S) diagrams drawn from the data presented in the CCOFI re p o rts . P la te IV, Figure 10, i s a record of the T-S values from a l l of the CCOFI s ta tio n s . Most of the values fo r water below one hundred meters are as those given fo r C entral P a c ific water. Sverdrup, et_ a l . (1941), on page 741 i l l u s t r a t e the T-S values fo r d if f e r e n t water masses. Those values were used fo r comparison with the CCOFI measurements. Most of the T-S values fo r the Outer Santa Barbara Passage appear to in d ic a te th a t the Passage i s an area o f mixing of East and West North C entral P a c ific water re fe rre d to as North P a c ific C entral w ater. In some cases T-S values approach readings in d ic a tiv e of P a cific E q u a to ria l w ater. These readings may r e f l e c t the in co rp o r atio n of southern water in to th e eddy system as the C a lifo rn ia Current tu rn s northward along the southern C a lifo rn ia coast. Figures 6 - 9 . — T e m p e ra tu r e-sa lin ity diagrams dravm from the data o f the CCOFI r e p o r ts. 31 PLATE III 20 - 20 - 15 - 15 - 10- 10- 6 Apr, Jan. 20 - 15 - 10- 8 Nov. Figure 1 0 .— Composite te m p e r a tu r e -s a lin ity diagram of a l l four CCOFI s t a t i o n s . 33 PLATE IV 34 20 - T 10- 10 35 I t appears, th en , t h a t lo c a l w aters are not simply a mixture of northern Subarctic water and southern P a c ific water, but ra th e r include some North P a c ific C entral water in tru d in g eastward from i t s major gyre. The surface w aters, above one hundred m eters, are subject to a g re a t deal of seasonal v a r ia tio n , e s p e c ia lly in tem perature. The surface s a l i n i t y values are ty p ic a l of those given fo r P a c ific S ubarctic water. This upper one hundred meters o f water may be S ubarctic water which has been heated by so la r ra d ia tio n with very l i t t l e change in s a lin it y as i t i s brought south by the C a lifo rn ia Current. CHAPTER II THE MID-WATER AMPHIPOD FAUNA OF SOUTHERN CALIFORNIA W ATERS Species Accounts, Outer Santa Barbara Passage The follow ing section p rese n ts inform ation on the v ario u s species o f amphipods c o lle c te d in the w aters over the Santa C atalina Basin. For each species the follow ing inform ation is given: References T otal number c o lle c te d Table of: S ta tio n s , num ber/pint, depth, number/trawl hour Geographical d is t r ib u t io n V e r tic a l d is t r ib u t io n and m igration Reproductive cycle Suborder Gammaridea Family E u sirid ae Rhachotropis n a ta to r (Holmes) G ra cilip es n a ta to r Holmes (190$), pp. 527-529, f ig s . 32-34; Thorsteinson (1941), p. $5, p i. 6 , f ig s . 67-70. Rhachotropis n a t a t o r , Barnard, J. L. (1954), pp. 54-56, p i. 6 . A t o t a l of seventy-seven specimens of t h i s species was so rted from p in t a liq u o ts during t h i s study. Several 37 others were noted in q u a lita tiv e samples. A ll in d iv id u a ls were females; the males are unknown. Table 8 i s a record of the s ta tio n s from which Rhachotropis n a ta to r was co lle c ted . TABLE 5 . - -S ta tio n l i s t and sampling data fo r R. n a ta to r S tatio n No. Day-night N o./Pint Depth (m) No./Trawl Hour 5115 D 5 927 32 5122 N 2 945 5 5242 D 1 560 4 5295 D 7 954 25 5346 D 5 500 20 #349 D 10 900 40 5430 D 9 500 36 5509 D 3 600 24 5697 D 6 1 0 0 0 (plus) 24 5700 D 5 550 32 5795 D 1 770 4 5959 D 17 1000 36 5964 N present 1 0 0 0 (plus) 9056 D present 1100 9245 N present 1100 Geographical d i s t r i b u t i o n . —Rhachotropis n a ta to r i s known only from the w aters o ff the coast of southern C alifo rn ia (Barnard, J. L . , 1954)* V e rtic a l d is tr ib u tio n and m ig ra tio n . --Specimens of Rhachotropis n a ta to r were never taken a t depths o f le ss than 600 m eters. Barnard, J. L. (1954), reported th is species to be known from depths of from 447 to 2225 fathoms (515 to 3965 m ). Table 9, based on the percentages of 38 p o s itiv e samples, provides some evidence of a m igration upwards during the daytime. TABLE 9 -—Percentages o f p o s itiv e samples for R. n a ta to r a t d if f e r e n t depths during the day and n ig h t Depth T otal No. No. P o sitiv e Percentage Range (m) Samples Hauls P o s itiv e Night 600- 900 b 0 0% 9 0 0 -1 1 0 0 3 3 100% Day 6 0 0- 900 11 6 5b. 5% 900-1100 6 6 15 % o These data in d ic a te th a t a t le a s t some o f the population moved to shallow er depths during the d ay lig h t h o u rs. Reproductive c y c le . —None of the specimens c o lle c te d were found to be carrying ova or young in the brood pouches. There was some v a ria tio n in siz e range and population den s ity during d if f e r e n t tim es of the year. Table 10 i l l u s t r a t e s th ese v a r ia tio n s . Since a r is e in population d en sity accompanied an extension of the lower lim it o f the siz e range, i t may be th a t the w inter months rep rese n t the time of re le a s e of young in to the ad u lt population. The d a ta a re , however, 39 too sparse fo r one to draw any d e f in it e conclusions concerning the reproductive a c t i v i t y of t h i s sp ecies. TABLE 10.--S easonal changes in size range and numbers per traw l hour for Rhachotropis n a ta to r Season Size Range Average No./Trawl Hour (P o sitiv e Hauls Only) Winter 9 - l 6m m 32 Spring 9-17mm 24 Summer 20mm(one 4 specimen) F a ll 13- 17m m 22 Family Lysianassidae Eurythenes obesus (Chevreux) Katius obesus Chevreux (1905), pp. 1-5, f ig s . 1-3; Stephensen (1925), pp. 126-127; Schellenberg ( 1 9 2 6), pp. 217-21$, fig . 26d; Barnard, K. H. (1932), pp. 56-5$, f ig . 21, p i. 1, f ig . 1; Chevreux (1935), pp. 63-65, p i. 10, f ig s . 4 , 6 , p i. 1 1 , f i g . 1 0 . Eurythenes obesus Shoemaker (1956), pp. 177-17$; Barnard, J. L. (1961), pp. 3$-39, fig . $. Only s ix specimens of t h i s species were c o lle c te d during the e n t ir e study. Table 11 l i s t s the s ta tio n s in which Eurythenes obesus was c o lle c te d . Geographical d i s t r i b u t i o n . —Barnard, J. L. (1961), rep o rted the d is t r ib u t io n of Eurythenes obesus as cosmopolitan between the polar c i r c l e s . 40 TABLE 1 1 .—S ta tio n l i s t and sampling data fo r E. obesus S tatio n No. Day-night Number Specimens Size Depth (m) S23S D 1 male 25 m m 975 2295 D 1 female 34 m m 954 #346 D 1 male 2# m m 9S0 9060 D 2 females 2 3 ,2 6 m m 6S5 9245 N 1 female 35 m m 1000 V e rtic a l d is tr ib u tio n and m ig ra tio n .--The p o s s i b i l i t y of demersal a c t i v i t y fo r t h i s species was suggested by Barnard (1961). He rep o rted on amphipods c o lle c te d by the Galathea expedition and noted th a t i n d i v i duals of Eurythenes obesus had been taken in both benthic and p elagic samples. Barnard s tip u la te d the p o s s i b i l i t y of benthic gear capturing p elag ic organisms. The specimens taken in t h i s p re se n t study were c e r ta in ly many meters o ff the bottom. Gut a n a ly sis of one in d iv id u a l revealed the presence of much d e b ris and what appeared to be s i l i c i o u s sponge sp icu les which may in d ic a te benthic feeding h a b its . I f th is species does engage in benthic feeding i t must m igrate v e r t i c a l l y some fiv e hundred to six hundred meters as in d ic ated by the capture depths. Barnard, J. L. ( 1 9 6 1), rep o rted the v e r t i c a l range fo r Eurythenes obesus to be from fiv e hundred to f i f t y - s i x hundred ten m eters; a l l of th e in d iv id u a ls taken in t h i s p rese n t study were captured w ithin t h i s range. 41 Reproductive c y c le . —In d iv id u a ls of t h i s species were taken only during the months of October through January. The l i f e - h i s t o r y im p licatio n s of t h i s f a c t are u n clea r because of the small number of specimens captured. Paracallisom a coecus (Holmes) Scopelocheirus coecus Holmes (1903), pp. 500-502, f ig s . 10-12; Barnard, J. L. (1954), p. 54, p i. 4-5. Paracallisom a coecus Barnard, J. L. (1959), p. 57. The t o t a l number of specimens of t h i s species recorded from p in t a liq u o ts was f i f t y - s i x ; se v e ral more were co llec ted in q u a lita tiv e samples. Table 12 l i s t s the s ta tio n s in which Paracallisom a coecus was found and the ap p ro p riate sample data. TABLE 1 2 .- -S ta tio n l i s t and sample data fo r Paracallisom a coecus S ta tio n No. Day-night M ales/ Females/ P in t P in t Depth (m) No./Trawl Hour 3122 N 0 4 945 16 $23$ D 2 16 975 72 3242 D 1 0 360 4 3295 D 2 6 954 32 3346 D 0 5 930 20 $349 D 1 5 900 24 3430 D 0 2 520 3 3509 D 0 1 600 4 3697 D 0 10 1100 40 3795 D 0 1 770 4 3959 D p resen t 1000 3964 N present 1 0 0 0 (plus) 9056 D present 1100 9243 N present 370 42 Geographical d i s t r i b u t i o n . —Paracallisom a coecus i s known only from the w aters o f f the coast of southern C a lifo rn ia (Barnard, J. L . , 1954). V e r tic a l d is tr ib u tio n and m ig ratio n . —Barnard, J. L. (1954), rep o rted a v e r t i c a l depth range of from 654 to 1030 fathoms (1196 to 1GB4 m eters) fo r t h i s sp ecies. A ll of th e specimens taken in t h i s present study were from shallow er depths than the upper lim it of the above-stated range. Paracallisom a coecus was captured in traw ls taken a t depths ranging from 520 to 1100 m eters. There e x is ts the p o s s i b i l i t y of some upward movement during th e d ay lig h t hours. Table 13 shows th a t th e species was captured in g re a te r numbers during the daytime, sug gestin g th a t some of the population was a t g re a te r depths than were sampled during t h i s study. TABLE 13.—Day and night depth d is tr ib u tio n fo r Paracallisom a coecus based on the percentages of p o sitiv e samples Depth T otal No. No. P o sitiv e Percentage Range (m) Hauls Hauls P o sitiv e Hauls Night 500- 900 11 2 9 0 0 -1 1 0 0 3 2 66% Day 500- 900 14 4 29% 9 0 0 -1 1 0 0 8 6 75% 43 I t i s obvious from the v a ria tio n in number per traw l hour with depth th a t t h i s species was scarce a t depths of le s s than nine hundred m eters. The average number per traw l hour in the p o s itiv e q u a n tita tiv e samples above nine hundred m eters was six, while t h i s fig u re fo r the p o s itiv e q u a n tita tiv e samples below nine hundred meters was t h i r t y - s ix . These values c e rta in ly in d ic a te , along with the inform ation in Table 13, th a t the bulk of the population was below nine hundred m eters. Again, the percentages of p o s itiv e samples did in c re ase during the d ay lig h t hours, suggesting some d iu rn a l movement. Reproductive c y c le .--The presence of ovigerous females was noted in October and November and young were found in the brood pouches of some females during May. Seasonal v a r ia tio n s in number and size o f fe r no data with which the presence of ova and young can be c o rre la te d . The seasonal size ranges fo r Paracallisom a coecus were as follow s: Winter $-18 m m Spring 10-17 m m Summer 12 m m (one specimen) F a ll $-19 m m Cyphocaris anonyx Boeck Cyphocaris micrononyx Stebbing (1888), p. 6 5 6 , p i. 16. Cyphocaris anonyx Boeck (1871), pp. 104-105; Schellenberg (1926), pp. 210-212, f ig s . 2b, 5a-b, p i. 5, f ig . 2; Schellenberg (1927), pp. 662-663, f ig . 57; Schellenberg 44 (1929), p . 195; Stephensen (1935), pp. 42-43; Shoemaker (1945), p . 187, f ig s . la -b ; Barnard , J. L. (1954), p • 53; Waterman (1939), pp. 256-279. A t o t a l of 115 specimens of Cyphocaris anonyx was recovered from p in t a liq u o ts during t h i s study and sev eral more were co llec ted in q u a lita tiv e samples. Table 14 l i s t s the p o s itiv e s ta tio n s and sample data fo r t h i s species • TABLE 14. —S ta tio n lis t and sample data for Cyphocaris anonyx S ta tio n No./Trawl No. Day-night N o./P int Depth (m) Hour 80 24 D 1 378 4 B026 D 1 504 4 8030 N 3 540 12 8031 N 1 540 4 8111 D 4 750 16 8114 D 1 650 4 8115 N 3 750 12 8117 N 17 650 68 8238 D 1 975 4 8242 D 1 860 4 8243 D 1 600 4 8291 D 1 562 4 8346 D 2 980 8 8349 D 3 900 12 8350 D 2 385 8 8427 D 4 520 16 8430 D 5 800 20 8509 D 1 600 8 8698 N 1 150 4 8700 D 1 850 4 8702 D 5 275 20 8711 D 29 490 116 8716 N 5 425 20 8788 D 21 455 84 8795 D 1 770 4 8959 D prese n t 1000 9056 D p rese n t 1100 45 Geographical d i s t r i b u t i o n . —Shoemaker (1945) gave the d is t r ib u t io n of Cyphocaris anonyx as the North and South A tla n tic , North and South P a c ific , th e East Indies and the Indian Ocean. Barnard, J. L. (1954), reported the f i r s t record of th is species from the P a c ific coast of North America. V e rtic a l d is trib u tio n and m ig ra tio n . —Shoemaker ( 1 9 4 5) recorded t h i s species from depths ranging from 600 to 1000 fathoms (1161 to 1935 meters) and th e sin g le sp e c i men recorded by Barnard, J. L. (1954), was taken in a net tow from 560 to 640 fathoms ( 10$4 to 1239 m eters). Waterman et a l. (1939) rep o rt Cyphocaris anonyx from much shallower depths than the above c ite d ones. His work showed t h i s species to be common w ithin a depth range of from about two hundred to one thousand m eters. This present study revealed specimens of C. anonyx in samples ranging in depth from one hundred f i f t y to eleven hundred m eters. Waterman (1939) discussed th e v e r t i c a l m igration of t h i s species and recorded a large portion o f the population moving from six hundred m eters in the d ay lig h t hours to about two hundred meters at n ig h t. There was some evidence of such a m igration in th is present study but i t i s not conclusive. The best support o ffe re d here fo r a m igratory h a b it i s th a t specimens were not captured in any of the 46 night s ta tio n s which were taken deeper than seven hundred f i f t y meters but were taken in several of the day s ta tio n s a t g re a te r depths. Reproductive c y c le . —Ovigerous females were noted during May, June, Ju ly , and August, in d ic a tin g th is time to be a period of high reproductive a c t i v i t y . No females were found to be carry in g young in the brood pouches. P la te V, Figure 11, i s a record of the v a ria tio n in mean size and size range 'throughout the year. There was an extension of the lower lim it of the size range in the summer and a s ig n if ic a n t drop in the mean size during the f a l l . These data a re based on measurements of seventy-four in d iv id u a ls . The following l i s t of changes in the number per traw l hour fo r each month shows an in c re ase in population density during the summer. Month No./Trawl Hour (P o sitiv e Hauls Only) January 1# February (no q u a n tita tiv e data) March 8 A p ril (no q u a n tita tiv e data) May 9 June 52 July 44 August 15 September 0 October 4 November 0 December 9 These data in d ic a te th a t the young were probably re le ase d in to the mature population during the summer months. Figure 1 1 .--Seasonal v a ria tio n in mean size and size range fo r Cyphocaris anonyx. Connected p oints in d ic a te mean siz e and v e r t i c a l lin e s in d ic a te size ranges. W - Winter Sp - Spring Su - Summer F - F a ll 47 PLATE V C. anonyx 15- 10- size mm Su 11 Cyphocaris ric h a rd i Chevreux Cyphocaris Richardi Chevreux (1905), pp. 1-5, fig s . 1-2; Stephensen (1915), pp. 37-3$, fig s . 21-22; Chevreux (1916), p. 1. Cyphocaris r i c h a r d i , Stebbing (1910), p. 449; Barnard, K. H. (1916), pp. 116-117; Schellenberg (1926a), p. 206- 209, f ig s . 2a, 3a-e, 4a-d, p i. 5, f ig . 1; Schellenberg (1926b), p. 245, fig . 4; Schellenberg (1929), p. 195; Barnard, K. H. (1932), p. 35; Stephensen (1933), pp. 4-5; Shoemaker (1945), pp. 137-139, fig* Id; Barnard, J. L. (1954), p. 54, p i. 2-3; Barnard, J. L. (1961), p. 32; Barnard, J. L. (1962), p. 24; B arnstein and Vinogradov (1955), pp. 212-213, f i g s . 2-3; B ernstein and Vinogradov (1953), p. 221. Specimens of Cyphocaris r ic h a rd i c o lle c te d from p in t a liq u o ts to ta le d 193 in d iv id u a ls . Several o th e rs were recorded from q u a l ita tiv e samples. Table 15 l i s t s the p o s itiv e s ta tio n s and sample data for Cyphocaris r i c h a r d i . Geographical d i s t r i b u t i o n .--C onsidered a cosmopolitan species, Cyphocaris r ic h a r d i was f i r s t recorded from P a c ific North America by Barnard, J. L. (1954). V e rtic a l d is t r ib u t io n and m ig ra tio n . —B ernstein and Vinogradov (1955) reported Cyphocaris r ic h a rd i taken in traw ls below 4200 meters and as shallow as 75 m eters. TABLE 1 5 .—S ta tio n l i s t and sample d ata fo r Cyphocaris ric h a rd i S tatio n Mo. Day- night Females/ M ales/ P in t P in t Juve n i l e s / P in t Depth (m) No./ Trawl Hour S i l l D 0 0 1 750 £115 N 15 11 3 750 116 SllB D 3 2 0 927 20 £122 N 1 0 0 945 4 S23S D 2 3 0 975 20 £242 D 12 20 0 £60 12S £291 D 2 4 0 526 24 8295 D 11 15 0 954 104 £346 D 1 6 0 9S0 2£ £349 D 13 15 0 900 112 £427 D 2 0 0 520 £ £430 D 5 9 0 £00 56 S509 D 4 3 0 600 56 £697 D 3 1 0 1000(plus) 2£ £700 D 10 7 0 £50 6B £710 N 0 2 0 £90 £ £712 D 0 1 1 700 £ 3795 D 5 1 0 770 24 £796 D 3 0 0 700 12 £959 D present 1000 £964 N present 1000 9056 D present 1100 9060 D present 6S5 9166 N present 600 9243 N present £70 9245 N present 1000 9347 N present 550 9349 N present 550 Barnard, J. L. (1962), rep o rted specimens from a bottom traw l a t 4&93 m eters. A ll of the specimens of t h i s species taken in t h i s present study were from depths g re a te r than 500 m eters and in d iv id u a ls were c o lle c te d from the deepest samples taken a t 1100 m eters. Table 16 i l l u s t r a t e s the 51 depth d is tr ib u tio n of th is species on the b a s is of the percentages of p o s itiv e tra w ls . TABLE 1 6 .—V e rtic a l d is t r ib u t io n of Cyphocaris ric h a rd i determined by day and night samples Depth (m) Total No. Hauls No. P o sitiv e Hauls Percentage P o s itiv e Hauls Night 500- 900 11 6 55% 900-1100 3 3 100% Day 500- 900 16 12 75% 900-1100 6 7 88% From these d ata i t can be seen th a t C. r ic h a rd i i s r a th e r evenly d is trib u te d between fiv e hundred and eleven hundred m eters. E a r lie r work has suggested th a t th is species is found much deeper than eleven hundred m eters. The sampling program of t h i s present study probably did not reach the lower lim it of the depth range. Reproductive c y c le . - -P la te VI, Figure 13, i s a record of th e percentages of mature females carrying ova and young in the brood pouches. These values are based on observations of eighty-one in d iv id u a ls . Ovigerous females were noted to p e r s is t a t a l l tim es of the year but were most p rev alen t in the f a l l months. Young were present in Figure 1 2 .--V a ria tio n in mean size and size range for Cyphocaris r i c h a r d i . H orizontal bars in summer and f a l l in d ic a te modes. Figure 1 3 .--V aria tio n in the percentages of mature females carrying ova and young throughout the year (C. r ic h a r d i) . o - ova y - young 52 PLATE VI 100- 75 - 25 - the brood pouches only during the w in te r. The seasonal v a r ia tio n in the r a t i o between the number of females per male was as follows (based on the t o t a l number of c o lle c te d in d iv id u a ls ). This r a tio was lowest during the time of maximum ova production. I t appears th a t development occurred during the f a l l and ea rly w inter with the re le a s e of young from the brood pouches taking place by March. and range throughout the year. These fig u re s are based on measurements of s ix ty specimens. The lowered mean in the summer and f a l l months was produced by the appearance of numerous small in d iv id u a ls r e s u ltin g in a bimodal size d i s t r ib u t io n . I t i s probable th a t summer and f a l l r e p r e sent th e time of the a d d itio n of young to th e mature popu la tio n . The lower mode was noted to progress from 17 to IS m m while the higher mode remained constant a t 23 mm. The change in the lower mode apparently r e f l e c t s the growth of th e young members o f the population. sp ecies, a lag between the time o f the re le a s e o f young from the brood pouches and t h e i r entrance in to the Females/male Winter Spring Summer F a ll P late VI, Figure 12, shows the change in mean siz e There was observed, in Cyphocaris r ic h a r d i and other 55 "catchable" population. In C.. ric h a rd i the young were released from the brood pouches by March but were not an influence on the size data u n t i l summer, a t which time the sm allest in d iv id u a ls captured were 11 m m in length which i s much la rg e r than newly release d young. The whereabouts of nev/born amphipods is sp e cu lativ e. The follow ing l i s t i s a record of the v a ria tio n in the number per tra w l hour fo r C. r ic h a rd i fo r various months of q u a n tita tiv e sampling. Included here are only those traw ls taken a t depths o f fiv e hundred meters or more. Month No./Trawl Hour January A February no q u a n tita tiv e data March 7 A pril no q u a n tita tiv e data May 1 June 1 July 1 August 1.6 September 1 October 6.6 November 5-2 December 8 Qrchomenella Sars A t o t a l of 553 in d iv id u a ls of th is genus was c o lle c te d during t h i s study. Although s p e c ific i d e n t i f i c a tio n was not attem pted here, the read er is re fe rre d to Hurley (1963), page 119, for a discussion of the systema- t i c s of t h i s genus and a key to the lo c a l species. 56 Table 17 l i s t s the s ta tio n s from which in d iv id u a ls of the genus Qrchomenella were c o lle c te d . TABLE 1 7 .—S tatio n l i s t and sample data for Qrchomenella S ta tio n No. Day-night N o./Pint Depth (m) No./Trawl Hour 3115 N 1 750 4 3113 D 50 927 200 3120 D 35 945 110 3121 D 1 360 4 3122 N 10 945 40 3233 D 61 975 244 3242 D 14 360 56 3291 D 1 562 4 3295 D 75 954 300 3346 D 61 930 244 3349 D 17 900 63 3350 D 39 300 156 3$09 D 2 600 16 3697 D 93 1000(plus) 372 3700 D 27 350 103 3710 N 12 390 43 3712 D 21 700 31 3795 D 7 770 23 3796 D 26 700 104 3959 D p resen t 1000 3964 N p rese n t 1000(plus) 9056 D present 1100 Geographical d i s t r i b u t i o n .- -There are th re e species of Qrchomenella rep o rted by Hurley (1963) as occurring o ff the coast of C a lifo rn ia . These species are Qrchomenella d ec ip en s. 0. obtusa, and 0. holm esi. V e rtic a l d is t r ib u t io n and m ig ra tio n . —In d iv id u a ls of t h i s genus were c o llec ted a t depths ranging from 360 to 1100 m eters. As the genus i s p rim arily a d ee p -liv in g one, 57 the sin g le record in s ta tio n 8121 a t 360 m eters i s questionable and may be the r e s u l t of contamination from the preceding sample (8120) a t 945 m eters. There was no evidence of a d iu rn a l m igratory p a tte rn in t h i s genus. The population appeared to be r a th e r evenly d is trib u te d in a th ic k zone from about seven hundred to eleven hundred m eters, with occasional catches from shallower depths. Reproductive c y c le .--Q vigerous females were noted in May, September, October, December, and January and young were p resen t in the brood pouches during September through January. Since th is group was tre a te d on the generic le v el no i n te r p r e t a ti o n of th is inform ation i s made as more than one species may be involved. Suborder Hyperiidea Family P la ty s c e lid a e P la ty sc e lu s s e rr a tu lu s Stebbing P la ty sc e lu s s e rra tu lu s Stebbing (1888), p. 1470; Stephensen (1925), pp. 215-218, ch art 31; Chevreux e t Fage (1925), p. 422, f ig . 414; Barnard, K. H. (1930), p. 437; P i r l o t (1930), p. 37; Barnard, K. H. (1932), p. 298; Shoemaker (1945), p. 259; Hurley (1956), pp. 21-22. Only e ig h t specimens o f t h i s species were co llec ted during t h i s study and a l l of th ese were fem ales. Table 18 l i s t s the p o s itiv e s ta tio n s fo r P. s e rr a tu lu s . 58 TABLE 1 8 .—S ta tio n l i s t and sample data fo r P la ty sc e lu s s e rr a tu lu s S tatio n No. Day-night No. /P in t Size (mm) Depth (m) 8118 D 1 5 927 8121 D 2 5,7 360 8122 N 1 5 360 8291 D 1 5 562 8292 N 1 4 170 8293 N 2 3,7 562 Geographical d i s t r i b u t i o n .--T h is i s considered to be a cosmopolitan sp ecies. Stephensen (1925) reported the f i r s t P a c ific record o ff the east coast o f New Zealand. Shoemaker (1945) recorded a d d itio n a l P a c ific occurrences o ff Baja C a lifo rn ia and Hurley (1956) reported on two specimens o ff southern C a lifo rn ia . V e rtic a l d is t r ib u t io n and m ig ra tio n . —Specimens taken in t h i s study were found in samples ranging in depth from 170 to 927 m eters. Stephensen (1925) reported fin d in g t h i s species at the surface at n ig h t. Although only a few in d iv id u a ls of P la ty sc e lu s s e rr a tu lu s were c o lle c te d , th e re i s some evidence of a v e r t i c a l m igration towards the s u r face a t n ig h t. The re p o rt by Stephensen in d ic ated such v e r t i c a l movement and the specimens taken by Hurley (1956) were taken a t times and depths also in d ic a tiv e of v e r t i c a l m igration. 59 Reproductive c y c le . —Ovigerous females were noted in November. This species was captured only during the months of November and September. H urley's specimens were taken in January and February. No conclusions concerning the reproductive a c t i v i t y can be drawn on the b asis of the few a v a ila b le specimens. Family Pronoidea Eupronoe minuta Claus Eupronoe m inuta, Stephensen (1925), pp. 160-161, fig s . 55-56; Chevreux et Fage (1925), pp. 425-426, f ig . 417; P i r l o t (1929), pp. 14S-149; Barnard, K. H. (1930), p. 426; P ir l o t (1930), pp. 34-35; Barnard, K. H. (1932), p. 2S9; Shoemaker (1945), pp. 245-246; Hurley (1956), p. 19. A t o t a l of 322 in d iv id u a ls o f th is species was so rted from p in t a liq u o ts and many others were noted in q u a lita tiv e samples. Table 19 l i s t s the s ta tio n s in which Eupronoe minuta was found. Geographical d i s t r i b u t i o n . —Eupronoe minuta has been recorded from the A tla n tic and Indian Oceans and the M editerranean Sea (Stephensen, 1925). Hurley (1956) f i r s t recorded t h i s species from the waters o ff the P a c ific coast of North America (seven specimens). V e rtic a l d is t r ib u t io n and m ig ra tio n . —Specimens of t h i s species were taken in samples a t depths ranging from 60 TABLE 1 9 .—S tatio n l i s t and sample data for Eupronoe minuta S ta tio n Day- Females/ Males/ No. /Trawl No. night P int P in t Depth (m) Hour £026 D 2 0 504 8 £029 N 3 0 666 12 £111 D 7 0 750 28 £114 D 3 0 650 12 £116 N 2 0 400 8 £117 N 7 0 65O 28 £118 D 1 1 927 8 £119 D 23 1 288 96 £120 D 2 0 945 8 £121 D 134 8 360 568 £123 N 4 0 360 16 £238 D 0 1 975 4 £239 N 4 0 400 16 £242 D 13 1 £60 .56 £243 D 5 1 600 24 £291 D 7 4 650 44 £293 N 12 0 85 48 £295 D 6 2 954 32 £347 N 2 0 387 8 £350 D 1. 0 385 4 £427 D 14 0 520 56 £428 N 9 0 170 36 £430 D 3 0 £00 12 £511 dusk 1 0 275 16 £697 D 5 0 1000(plus) 20 £698 N 2 0 150 8 £700 D 2 0 £50 8 £702 D 5 0 275 20 £712 D 1 0 700 4 £717 N 6 0 £0 24 £789 N 1 0 190 4 8957 N p rese n t 50 £961 D (present in nup and 450 down” catch with £964 N Foxton device) 1000 9055 N present 150 9059 D present 325 9247 D very abundant 125 9350 D very abundant 165 9598 D very abundant 100 9599 D p resent 50 9601 D very abundant 100 61 f i f t y to one thousand m eters. Table 20 i l l u s t r a t e s the day and n ight depth d is t r ib u t io n s . TABLE 2 0 .--Day and n ig h t depth d is t r ib u t io n s of Eupronoe minuta based on the percentages of p o s itiv e samples Depth (m) Total No. Hauls No. P o sitiv e Hauls Percentage P o sitiv e Average No./ Trawl Hours (P o sitiv e Only) Night 0- 50 4 1 25% (few) 50- 100 2 2 100% 36 100- 200 7 4 5 7 $ 6 200- 300 4 0 0% ------- 3 0 0- 400 6 4 66% 12 400- 500 2 0 0% --- 50 0- 600 7 0 0% — — 600- 700 2 2 100% 20 700- 800 1 0 0% — — 800- 900 1 0 0% _____ 900-1100 3 0 0% — “ Day 0- 50 2 1 50% (many) 50- 100 2 2 100% (very many) 100- 200 2 2 100% (very many) 200- 300 4 2 56 300- 400 4 3 7 5 $ 286 400- 500 5 0 — 500- 600 5 3 60% 29 600- 700 4 3 75% 20 700- 800 3 2 66% 20 800- 900 4 2 50% 29 900-1000 8 5 62% 14 There appears to be a r i s i n g of the deeper p o rtio n of the population during the night hours. The reason fo r 62 th e e r r a t i c d is t r ib u t io n o f t h i s species i s not c le a r and i s discussed in a l a t e r section along with the v ario u s p a tte r n s o f m igration. Reproductive cy c le. —P la te VII, Figure 15, i s a record of the percentages of mature females with ova and young in the brood pouches. The breeding cycle i s not c le a r in th a t i t appeared th a t production o f ova and the presence of young coincided to a large degree. Young were apparently re le a se d in to th e mature population during the f a l l months. Figure 14 shows a s lig h t decrease in mean siz e and an extension o f the lower lim it o f the siz e range during t h i s period. Males were found only during the f a l l months. The follow ing l i s t of the v a ria tio n in number per traw l hour shows an increase in population density during the f a l l . Month No./Trawl Hour January 13 February no q u a n tita tiv e data March 4 A pril no q u a n tita tiv e data May 6 June 4 July 4 August 4 September 56 October 10 November 12 December 4 The data presented in Figures 14 and 15 are based on th e observations and measurements o f 235 in d iv id u a ls . 1 Figure 1 4 .—Seasonal v a ria tio n in mean size and size range fo r Eupronoe minuta. f - females m - males Figure 1 5 .—Seasonal v a ria tio n in the percentages of mature females of E. minuta carrying ova and young. 63 PLATE V2I size mm 14 75 - 50 - 25 - 65 Family Phrosinidae Primno macropa Guerin Euprimno macropa, Stephensen (1924), pp. 143-146, c h a rt 22; P i r l o t (1929), pp. 130-131; P i r l o t (1930), p. 22; Stephensen (1947), p. 77. Primno macropa, Barnard, K. H. (1930), pp. 424-425; Barnard, K. H. (1932), pp. 2&7-28G; Thorsteinson (1941), pp. 93-94, p i. 9, f ig s . 98-102; Mackintosh (1934), p. 90, f ig . 20; Shoemaker (1945), pp. 234-236; Hurley (1956), pp. 17-18. Primno macropa was a common re p re s e n ta tiv e of the amphipods taken in th is study. Three hundred f if t e e n i n d i v id u als were taken from p in t a liq u o ts and a few o th ers were noted in c e rta in q u a lita tiv e samples. Table 21 l i s t s the p o s itiv e s ta tio n s for t h i s species. Geographical d i s t r i b u t i o n . - - Primno macropa is considered a widely d is tr ib u te d , cosmopolitan species. I t has been recorded from the w aters o ff southern C a lifo rn ia by Hurley (1956). V e rtic a l d is tr ib u tio n and m ig ra tio n . —Mackintosh (1934) o ffe red data which suggest th a t t h i s species m igrates to the surface during the day lig h t hours and moves deeper a t n ig h t. That work was done in A n tarctic w aters. From t h i s present study th e re i s d e f in it e evidence of a ty p ic a l m igratory p a tte rn towards the surface a t night 66 TABLE 21. —S tatio n l i s t and sample data fo r Primno macropa S tatio n No. Day- night Females/ Pint Males/ P int Depth , No. /Trawl (m) Hour 802 A D 1 0 378 4 8025 N 1 0 522 4 8029 N 6 0 666 ' 24 8030 N 2 1 540 12 8031 N 1 0 540 4 8111 D 19 2 750 84 8114 D 6 1 650 28 8115 N 1 0 750 4 8116 N 7 1 4 00 32 8117 N 9 0 650 36 8118 D 4 2 927 24 8119 D 53 23 288 304 8120 D 2 0 945 8 8121 D 42 3 360 180 8123 N 42 3 360 180 8238 D 2 0 975 8 8240 N 4 0 300 16 8242 D 2 0 860 8 8243 D 3 1 600 16 8291 D 1 0 562 4 8292 N 3 2 170 20 8293 N 26 1 85 108 8296 D 1 0 500 4 8298 N present 475 8346 D 2 0 980 8 8347 N 2 0 387 8 8427 D 2 0 520 8 8428 N 5 0 170 20 8430 D 4 0 800 16 8506 D 4 0 300 64 8 508 dusk 1 0 425 8 8511 dusk 2 0 275 32 8698 N 3 0 150 12 8702 D 1 0 275 4 8711 D 1 1 490 8 8716 N 1 0 435 4 8717 N 5 0 80 20 8788 D 2 0 , 455 8 8795 D 1 0 770 4 9167 N p rese n t 200 67 and a r e t r e a t to deeper w ater during the day. The daytime depth range was from two hundred to nine hundred eighty m eters and the nighttim e depth range was from eighty to s ix hundred f i f t y m eters. Reproductive c y c le . —P la te V III, Figure 17, shows the percentages of mature females carrying ova and young throughout the study period. Maximum egg production occurred in th e summer and f a l l with a high incidence of young in the brood pouches by spring. Young were released in to the catchable population by summer. Figure 16 shows a drop in mean size and an extension of the lower lim it of the size range during the time of entrance of young in to the population. Males were present only during the summer and f a l l months when ova production was high. Below are l i s t e d the numbers per traw l hour for months of q u a n tita tiv e sampling. Month No. /Trawl Hour January 5 February no q u a n tita tiv e data March 5 A pril no q u a n tita tiv e data May 3 June 3 July 3 August £ September 60 October 5 November 12 December 3 Figure 1 6 .—Seasonal v a ria tio n in mean size and siz e range fo r Primno macropa. f - females m - males Figure 1 ? .--S easonal v a ria tio n in the percentages of mature females of P. macropa carrying ova and young. 68 PLATE VIII 2 0 - 15- size mm W 16 100 75 - 50 - 25 - w 17 70 The size and reproductive data presented fo r Primno macropa were based on the measurements and observations of 166 specimens. Family Cystisomidae Cystisoma f a b r i c i i Stebbing Thaumatops F a b r i c i i , Stephensen (1918), pp. 63- 6 4 , f ig s . 22-23; P i r l o t (1929), p. 89. Cystisoma f a b r i c i i Stebbing (1888), p. 1333; Barnard, K. H. (1932), pp. 272-273; Hurley (1956), p. 10. Most of the in d iv id u a ls of t h i s species were taken in shipboard s o rtin g . They were not abundant and p in t a liq u o ts produced very few specimens. A t o t a l of t h i r t y - one in d iv id u a ls was c o lle c ted . Table 22 l i s t s the p o s itiv e s ta tio n s fo r Cystisoma f a b r i c i i . Geographical d i s t r i b u t i o n . --T his species i s known from the North A tla n tic and the In d o -P acific Oceans. Hurley (1956) rep o rted th e f i r s t record from the coast of southern C a lifo rn ia . V e rtic a l d i s t r ib u t io n and m ig ra tio n . - - Cystisoma f a b r i c i i was taken in traw ls ranging in depth from 275 to 1000 m eters. There i s some evidence th a t t h i s species r i s e s towards the surface during the night hours but th is i s speculative due to the s c a rc ity of specimens. Reproductive c y c le . —Ovigerous females were noted in October and December and young were found being c a rrie d by 71 the females in January and August. There was an in c re ase in the number of males c o llec ted during the months of ova production. Again p au city of specimens prevents drawing conclusions. TABLE 2 2 .—S tatio n l i s t and sample data for Cystisoma f a b r i c i i S tatio n No. Day- night Females Males Depth (m) No. Size No. Size 6027 D 1 50 m m 0 468 8115 N 1 70 m m 0 --- 750 8116 N 2 3 6 ,5 0 m m 0 --- 400 8121 D 0 — 1 98 m m 360 8243 D 1 50 m m 0 600 8295 D 0 — 1 103 m m 954 8346 D 1 53 m m 0 ---- 980 6350 D 6 5 8 -7 0 m m 1 52 m m 385 8430 D 1 41 m m 2 71,75 m m 800 8697 D 1 73 m m 0 - - 1 0 0 0(plus) 8700 D 1 28 m m 0 ------ 850 8702 D 1 70 m m 0 --- 275 8711 D 2 6 5 ,75 m m 0 ------- 490 8716 N 1 28 m m 0 ------- 425 8788 D 2 2 2 ,5 0 m m 0 ------- 455 8795 D 1 29 m m 0 ------- 770 9245 N 1 76 m m 0 — — 1000 8958 N 2 2 4 ,6 0 m m 0 — - 285 8959 D 1 75 m m 0 “ — 1000 Cystisoma pellucidum (Suhn) Thaumatops p e llu c id a , Stephensen ( 1 9 1 8), pp. 64- 6 6 , f i g s . 19, 24-27. Cystisoma pellucidum . Barnard, K. H. (1932), p. 272; Thorsteinson (1941), pp. 92-93; Hurley (1956), p. 10. 72 Only four in d iv id u a ls of t h i s species were c o lle c te d during the study, a l l of which were taken in shipboard so rtin g . S ta tio n £027, day, 1 male, 70 mm, depth - 46£ m S tatio n £433, n ig h t, 1 male, 116 mm, depth - 300 m S tatio n £702, day, 1 damaged, 70 mm, depth - 275 m S ta tio n £7££, day, 1 female, 64 mm, depth - 455 m Geographical d i s t r i b u t i o n . —Barnard, K. H. (1932), reported the d i s t r ib u t io n of th i s species as the North A tla n tic and th e Indian Oceans. The f i r s t record from P a c ific North America was made by Thorstienson (1941). This species was recorded from southern C a lifo rn ia w aters by Hurley (1956). V e rtic a l d is t r ib u t io n and m ig ra tio n . —Specimens of Cystisoma pellucidum were taken in samples ranging in depth from 275 to 4 6£ m eters. Although v e r t i c a l m igration i s suspected in t h i s species the data are too scant to support the suggestion. Reproductive c y c le . —A sin g le ovigerous female was co llec ted in July; no o ther reproductive inform ation was obtained. Family Oxycephalidae Calamorhynchus rig id u s (Stebbing) Calamorhynchus p ellu cid u s S tr e e ts (1S7S), p. 2B5, p i. 2, fig . 5; B ovallius (l£90), pp. 73-74, p i. 2, f i g s . 14-15. 73 Calamorhynchus r i g i d u s , Stebbing (1$$$), p. 1600, p i. 206; B ovallius (1&90), p. 74; Stephensen (1925), pp. 1&9-191. A sin g le male specimen was co llec ted during t h i s study a t a depth o f }6 0 m eters ( s ta tio n $121). I t measured 19 m m in length. Geographical d i s t r i b u t i o n . —This species has been recorded p rev io u sly from th e M editerranean Sea and the A tla n tic and C entral P a c ific Oceans. B ovallius (l$90) considered Calamorhynchus p ellu cid u s a separate species but i t was synonomized with C _ . rig id u s in 1925 by Stephensen. I f C _ . p e llu cid u s i s a v a lid species t h i s study presen ts the f i r s t P a c ific record of C. r i g i d u s ; i f i t i s not, t h i s is the f i r s t record from the E astern P a c ific . V e rtic a l d is tr ib u tio n and m ig ra tio n .--D ata presented by Stephensen (1925) suggest a v e r t i c a l movement towards the surface during the n ig h t fo r t h i s species. This p re s ent study provides no a d d itio n a l inform ation since only one in d iv id u al was c o lle c te d . Reproductive c y c le . —Stebbing (1$8$) co llec ted one female with young during March in the South A tla n tic . No o th er inform ation i s a v a ila b le concerning the reproductive a c t i v i t y of t h i s species. Qxycephalus c la u si Bovallius Qxycephalus c la u si B ovallius (1$90), p. 60, f i g s . 4 , 7 , $, 2 2 , 5 4 , 6 5 , p i. i , fig s . 19-24, p i. i i , f ig . 1; Stephensen 74 (1925), p. 1$S, chart 27; Barnard, K. H. (1930), p. 433; Barnard, K. H. (1932), p. 294- Only two specimens of th is species were co llec ted during th i s study. S tatio n $121, day, 1 female, 30 mm, depth - 360 m S tation $427, day, 1 female, 25 mm, depth - 520 m Geographical d i s t r i b u t i o n . --T h is species has prev io u sly been rep o rted from the Southeast and East mid- A tla n tic (Barnard, K. H., 1932). I t i s also known from the M editerranean Sea and the In d o -P acific Ocean. B ovallius (1$90) gave i t s d is t r ib u t io n as a l l tr o p ic a l and sub tr o p ic a l seas. This present study re p re s e n ts the f i r s t record from P a c ific North America. V e rtic a l d is tr ib u tio n and m ig ra tio n . --B arnard, K. H. (1932), c o lle c te d specimens o f Qxycephalus c la u si in many shallow night tows, suggesting th a t th is species probably m igrates towards the surface during the dark hours. Reproductive c y c le . —Barnard, K. H. (1932), rep o rted fin d in g ovigerous females during August and females c a rry ing young in July. No reproductive inform ation was added by th is present study. S tr e e ts ia pronoides (Stebbing) S tr e e ts ia ch allen g eri Stebbing (1$$$), pp. 1603-1606, p i. 2 0 7 ; Stephensen (1925), pp. 194-199, f ig . 75; P i r l o t 75 (1929), pp. 1 6 4- 1 6 5 ; Barnard, K. H. (1930), p. 435; Barnard, K. H. (1932), p. 295; Shoemaker (1945), p. 255. S tr e e ts ia p ro n o id e s, Bovallius (1#90), p. 34, p i. I l l , f ig s . 7-12, p. 2 3 , f ig . 9 , p. 3 5 , f ig . 6 2 ; P i r l o t (193#), p. 360; Hurley (1956), pp. 1S-19. This species was by far the commonest oxycephalid taken during t h i s study. Sixty-seven in d iv id u als were so rted from p in t a liq u o ts and many o th ers were noted in c e rta in of the q u a lita tiv e samples. Table 23 l i s t s the p o s itiv e s ta tio n s fo r S. pronoides along with some of the sample data. Geographical d i s t r i b u t i o n . —Barnard, K. H. (1932), reported the d is t r ib u t io n of S tr e e ts ia pronoides as the A tla n tic and In d o -P ac ific Oceans and the M editerranean Sea. This species has been recorded o f f the coast of southern C a lifo rn ia by Hurley (1956). V e rtic a l d is t r ib u t io n and m ig ra tio n . —Specimens of th is species were taken in traw ls ranging in depth from ten to one thousand m eters. There i s d e f in ite evidence o f d iu rn a l m igration towards the surface a t nig h t as i l l u s tr a te d in Table 2 4 . The two p o s itiv e n ight hauls which are deep may be the r e s u lt of contamination from shallower depths, or they may r e f l e c t the presence of a non-m igrating portion of the population. Since t h i s species was p resen t in the "up and 76 down” catch of S ta tio n 8 9 6 4 using the Foxton device, but absent from the catch "a t d e p th ,” those deep records are probably from contamination. TABLE 23.—S ta tio n l i s t and sample data fo r S tr e e ts ia pronoides S ta tio n No. Day-night N o./Pint Depth (m) No./Trawl Hour 8027 D 2 350 3 3029 N 1 666 4 3113 D 1 927 4 3119 D 2 233 3 3121 D 3 360 12 3233 D 1 975 4 3240 N 2 300 3 3242 D 4 360 16 3292 N 1 170 4 3293 N 1 35 4 3350 D 2 335 3 3427 D 1 520 4 3503 dusk 3 427 24 3509 D 1 600 3 5697 D 5 1000(plus) 20 3693 N 4 150 16 3700 D 4 350 16 3702 D 1 275 4 3710 N 2 390 3 3711 D 2 490 3 3712 D 1 700 4 3717 N 2 30 8 3733 D 6 455 24 3739 N 14 190 56 3953 N p resent 235 3960 D present 275 3964 N {present in "up and down" catch with Foxton device —fished at 1000 m) 9053 N present 10 9054 N p resen t 50 9059 D present 325 9167 N p resent 200 77 TABLE 2 4 .--Day and n ig h t depth d is t r ib u t io n of S tr e e ts ia pronoides based on the percentages of p o s itiv e samples Depth (m) Mo. Hauls No. P o sitiv e Hauls Percentage P o sitiv e Hauls Might 0 - 50 4 2 5(# 50- 100 2 2 100 f0 100- 200 7 4 59% 200- 300 4 2 50% 3 0 0- 400 6 0 0% 4 0 0- 500 2 0 0% 5 0 0- 600 7 0 V % 600- 700 2 1 50% 700- 800 1 0 0% 8 0 0- 900 1 1 100% 900- 1000 3 0 0% Day 0 - 50 2 0 0 P / O 50- 100 2 '0 O P /0 100- 200 2 0 0% 200- 300 4 3 300- 400 4 4 100# 4 0 0- 500 5 2 4 0# 5 0 0- 600 5 2 40# 600- 700 4 1 25% 700- 800 3 0 0% 800- 900 4 2 50% 900- 1000 8 3 37% Reuroductive cycle.--T he percentages o'f mature females carrying ova and young in the brood pouches are shown in P la te IX, Figure 19. Egg production was h ig h est * in the spring and the h ig h e st percentages of females carrying young was noted in the f a l l . Young were apparently Figure 1 $ .—Seasonal v a ria tio n in mean size and size range fo r S tr e e ts ia pro n o id es. Figure 19-—Seasonal v a ria tio n in the percentages of mature females o f S. pronoides carrying ova and young. 78 PLATE IX 28H 21- size mm W W 18 100- 75 - 50 - 25 - w Su 19 w 80 re le a se d from the p aren ts in the la te f a l l and early w inter. The r a t i o between the number of females per male was low in the suggested period of ova production. Females/male Winter 2/1 Spring 3/1 Summer 8/1 F a ll 11/1 Figure 18 shows the v a ria tio n in mean size and size range fo r S tr e e ts ia pronoides throughout the year. There does not seem to be any d e f in ite c o rre la tio n between these data and the suggested reproductive tim es. The following l i s t gives the v a r ia tio n in the number per traw l hour for months of q u a n tita tiv e sampling. Month No./Trawl Hour January le s s than l /t r a w l hour February no q u a n tita tiv e data March 1.6 A pril no q u a n tita tiv e data May 4. 1 June 2.2 July 4 August le ss than l /t r a w l hour September 2 October 3 November le ss than l /t r a w l hour December le s s than l/t r a w l hour The above rep ro d u ctiv e and size data on S tr e e ts ia pronoides were determined by observations and measurements of one hundred ten in d iv id u a ls . 81 Family Hyperiidae Hyperia sp in ig era Bovallius Hyperia s p in ig e r a , Barnard, K. H. (1932), pp. 273-274-, fig . 160; Thorsteinson (1941), pp. 87-88, p i. 8, f ig s . 79-82; Shoemaker (1945), p. 23^, fig . 35; Hurley (1956), p. 15. I t was suggested by Shoemaker (1945) th a t t h i s species may be conspecific with Hyperia galba (Montague). Only eight specimens were c o lle c te d during t h i s study and a l l were males. Table 25 gives the s ta tio n s and sample data fo r H. s p in ig e r a . TABLE 2 5 .—S tatio n l i s t and sample data for Hyperia sp in ig era S tatio n No. Day- nig h t No./ p in t Si ze Depth (m) 8116 N 1 5 m m 400 8121 D 1 4 m m 360 8240 N 2 4,14 m m 300 8242 D 3 5 m m 860 8295 D 1 4 m m 954 Geographical d i s t r i b u t i o n . —Barnard, K. H. (1932), reported the d is tr ib u tio n of Hyperia sp in ig era as the West A tla n tic Ocean and A n ta rc tic w aters. There have h ith e rto been two specimens taken o f f the P a c ific coast of North America; one from Friday Harbor, Puget Sound, Washington 82 (Thorsteinson, 1941), and one o ff southern C a lifo rn ia (Hurley, 1956). V e rtic a l d is t r ib u t io n and m ig ra tio n . —Specimens of Hyperia spinigera were taken in tra w ls ranging in depth from 300 to 954 m eters. Although only a few in d iv id u a ls were c o lle c te d th e re i s some evidence o f v e r t i c a l m igration towards the surface a t n ig h t. The two shallow traw ls (300 and 4 0 0 meters) in which th i s species was taken were night samples and the two deep p o s itiv e samples (£60 and 954 meters) were taken during the daytime. Reproductive c y c le .--S in c e only males were captured no inform ation was obtained concerning the reproductive a c t i v i t y o f Hyperia s p in ig e r a . Hyperia bengalensis (G iles) Hyperia bengalensis Shoemaker (1942), p. 49; Shoemaker (1945), p. 23S; Hurley (1956), pp. 14-15. A g reat deal of taxonomic confusion accompanies t h i s species; see Hurley (1956) fo r an account of the system- a t i c s . The specimens taken in t h i s present study are very sim ila r to th a t p ic tu re d by Stebbing (1$BB) as Hyperia schizogeneios. A t o t a l of fifty -tw o in d iv id u a ls of t h i s species was c o lle c te d from p in t a liq u o ts . None were found in th e q u a lita tiv e samples. Table 26 l i s t s the p o s itiv e s ta tio n s fo r Hyperia b e n g a le n s is. 83 TABLE 2 6 .—S ta tio n l i s t and sample data fo r Hyperia bengalensis S tatio n No. Day- night No./ p in t Depth (m) No./Trawl Hour 8111 D 2 750 8 8114 D 1 650 4 8117 N 2 650 8 8 1 1 8 D 1 927 4 8119 D 7 288 28 8121 D 4 360 16 82 3 8 D 2 975 8 8242 D 6 860 24 8243 D 8 600 32 8291 D 6 650 24 8 2 9 2 N 3 170 12 8293 N 2 85 8 8295 D 8 954 32 Geographical d i s t r i b u t i o n .--T h is species has been recorded prev io u sly from the M editerranean Sea, th e North and South A tla n tic , and the South P a c ific . A sin g le specimen was reported by Shoemaker (1942) from the waters near the Galapagos Islan d s and Hurley (1956) rep o rted se v e ra l specimens from the w aters o f f the coast of southern C a lifo rn ia . V e rtic a l d is t r ib u t io n and m ig ra tio n . - - Hyperia bengalensis was c o lle c te d in traw ls ranging in depth from $5 to 975 m eters. There i s evidence of v e r t i c a l m igration towards th e surface at n ig h t. This species was present in s ta tio n s 82 9 2 and 8293 near the surface a t night but was absent from a l l o f the shallow daytime samples. 84 Reproductive c y c le . —In d iv id u a ls of t h i s species were only found during the months of August through November. P la te X, Figure 20, shows th e v a r ia tio n in the percentages of mature females carrying ova and young in the brood pouches during the months of p o s itiv e c o lle c tio n . The r a tio s between the number of females per male fo r those months of capture were as follow s: Month Females/male August no males September 5/1 October 1 5 /l November 3/1 Figure 21 i s a record of the mean siz e and size range v a ria tio n fo r August through November. The sudden appearance and disappearance of t h i s species in the lo c a l population i s u n clear and the breeding cycle i s consequently incomplete. Hyperia galba (Montague) Hyperia g a lb a , Sars (1$95), p. 7, p i. 2, f ig . 1; Caiman (1S9S), p. 2 6 5 ; Barnard, K. H. ( 1 9 1 6), p. 2$5; Stephensen (1924), p. S i, chart 11; Barnard, K. H. (1932), p. 273. One hundred and seventy-eight in d iv id u a ls of th is species were c o lle c te d from p in t a liq u o ts during th is study and sev eral more were recorded from q u a l ita tiv e samples. Table 27 l i s t s the p o s itiv e s ta tio n s and c e rta in sample data for Hyperia g a lb a . Figure 2 0 .—Seasonal v a ria tio n in mean siz e and size range fo r Hyperia b en g a len sis. Figure 21.--S easonal v a ria tio n in the percentages of mature females o f H. bengalensis carrying ova and young. o - ova y - young A - August S - September 0 - October N - November 85 PLATE X size mm W W 20 100- 75 - 50 - 25 - Su W 87 TABLE 2 7 .—S ta tio n l i s t and sample data fo r Hyperia galba S ta tio n No. Day-night N o./P int Depth (m) No./Trawl Hour 8024 D 13 387 52 8026 D 4 504 16 8116 N 5 400 20 8118 D 1 927 4 8238 D 4 975 16 8239 N 22 4 0 0 88 8240 N 13 300 52 8242 D 6 860 24 8243 D 3 600 12 8291 D 5 562 20 8292 N 13 170 52 8293 N 6 85 24 8295 D 5 954 20 8296 D 22 500 88 8298 N 7 475 28 8346 D 4 980 16 8347 N 1 387 4 8350 D 9 385 36 8427 D 1 520 4 8428 N 11 170 44 8430 D 4 800 16 8433 N 8 300 32 8506 D 7 300 28 8511 dusk 1 275 4 8512 N 1 230 . 4 8697 D 1 1000(plus) 4 8795 D 1 770 4 8958 N p rese n t 285 8959 D present 1000 8961 D p re se n t 450 8964 N (p resen t in ”up and down" Foxton d ev ice—fish ed at catch with 1000 meter) 9059 D p re se n t 325 Geographical d i s t r i b u t i o n . —Barnard, K. H. (1932), rep o rted the d is t r ib u t io n of Hyperia galba as the M editerranean Sea, the North and South A tla n tic , the 88 A rc tic , A n ta rc tic, and In d o -P ac ific Oceans. This species has previously been reported from the west coast of North America. V e rtic a l d is tr ib u tio n and m ig ratio n .--Specimens of Hyperia galba were c o lle c te d in traw ls taken a t depths ranging from e ig h ty -fiv e to one thousand m eters. Table 28 i l l u s t r a t e s the day and nig h t depth d is t r ib u t io n fo r th i s species. Reproductive c y c le . —The percentages o f mature females carrying ova and young during d if f e r e n t times of the year are shown in P la te XI, Figure 23. Egg production was highest in the summer and the highest percentages of females with young occurred in th e spring. The r a t i o s of females per male were as follow s: Females/male Winter 1.5/1 Spring 1.5/1 Summer 4.5/1 F a ll 4.6/1 P la te XI, Figure 22, i l l u s t r a t e s the v a r ia tio n in mean siz e and siz e range throughout the year. An extension of the lower lim it of the size range occurred in the f a l l , probably in d ic a tin g the time of the entrance of young into the "catchable" population. This suggestion i s supported by the in c re ase in population density in the f a l l as shown by the follow ing l i s t o f the v a ria tio n in number per traw l hour. Month January February March A pril May June No./Trawl Hour 16 no q u a n tita tiv e 7 data no q u a n tita tiv e 3 data 0 Month July August September October November December 89 No./Trawl Hour 3 3 3 18 18 6 TABLE 2 8 .--Day and nig h t depth d is t r ib u t io n for Hyperia galba based on the percentages of p o s itiv e samples Depth (m) No. Hauls No. P o sitiv e Hauls Percentage P o sitiv e Hauls Night 0- 50 4 0 o f 50- 100 2 1 50$ 100- 200 7 2 2S% 200- 300 4 4 100 fo 300- 400 6 3 50$ 4 0 0- 500 2 1 50% 5 0 0- 600 7 1 13* 600- 700 2 0 0% 700- 800 1 0 O ff 800- 900 1 0 0% 900-1000 3 0 Qffo Day 0- 50 2 0 Q ffo 50- 100 2 0 °# 100- 200 2 0 0% 200- 300 4 1 2 5% 3 0 0- 400 4 4 100 fo 400- 500 5 2 40 fo 500- 600 5 3 6<yfo 600- 700 4 0 Qffo 7 0 0- 800 3 2 75fo 800- 900 4 1 2 ^ i 9 0 0- 1000 8 6 75* Figure 2 2 .—Seasonal v a ria tio n in mean size and size range fo r Hyperia g a lb a . Figure 2 3 .—Seasonal v a ria tio n in the percentages of mature females of H. galba carrying ova and young. 90 PLATE XI 20i 15- size mm W 22 100 75 * 50-1 25 - There appears to have been about a three-month lag between the suggested time of the re le a s e of young from th brood pouches and the entrance of ju v e n ile s in to the catchable population. The whereabouts o f the newborn amphipods i s unknown. The data presented on Hyperia galba are based on observations and measurements o f one hundred eighty in d iv id u a ls. Family V ib iliid a e V ib ilia armata B ovallius V ib ilia arm ata, Chevreux et Fage (1925), pp. 3&7-3&B, f ig . 391; P i r l o t (1929), pp. 100-101; P ir l o t (1930), p. 11 Barnard, K. H. (1930), p. 104; Barnard, K. H. (1932), pp. 264-265; Hurley (1956), pp. 10-11. V ib ilia arrnata was among the commonest amphipods c o llec ted during t h i s study. A t o t a l of 2742 in d iv id u a ls was taken from p in t a liq u o ts and many o th e rs were noted in q u a lita tiv e samples. Table 29 l i s t s the p o s itiv e s ta tio n s fo r V. arm ata. Geographical d i s t r i b u t i o n . — Barnard, K. H. (1932), gave the d is t r ib u t io n o f V ib ilia armata as the A tla n tic , Indian, and Eastern P a c ific Oceans and th e M editerranean Sea. Hurley (1956) rep o rted the f i r s t record from the w aters o f f southern C a lifo rn ia . 93 TABLE 2 9 .—S tatio n l i s t and sample data fo r V ib ilia armata S tatio n Day- No./Trawl No. night No. /P in t Depth (m) Hour 8024 D 50 378 200 3025 N 16 522 64 3026 D 13 504 52 3027 D 2 4 68 8 3029 N 10 666 40 8030 N 7 540 28 8031 N 4 540 16 8111 D 46 750 184 8114 D 19 6 5O 76 8115 N 7 75 0 28 8116 N 4 4 00 16 8117 N 26 378 104 8118 D 45 927 180 8119 D 1 288 4 8120 D 29 945 116 8123 N 54 360 216 8238 D 52 975 208 8239 N 73 400 292 8240 N 28 300 112 8242 D 31 860 124 8243 D 720 600 2880 8291 D 31 562 124 8292 N 56 170 224 8293 N 406 85 1624 8295 D 79 954 316 8296 D 475 500 1900 8298 N p resen t 475 8346 D 1 980 4 8347 N 5 387 20 8349 D 6 900 24 8350 D 17 385 68 8427 D 67 520 268 8428 N 166 170 664 8430 D 17 500 68 8433 N 6 300 24 8506 D 35 300 140 8 5O 8 dusk 5 425 20 8697 D 6 1000(plus) 24 8698 N 6 150 24 8700 D 6 8 5 0 24 8702 D 50 275 200 8711 D 7 490 28 8712 D 1 700 4 TABLE 29--Continued 94 S tatio n Day- Mo. /Trawl No. night N o./P int Depth (m) Hour 8717 N 3 $0 12 $7$$ D 7 455 2$ $957 N present 50 $95$ N present 2$ 5 $961 D p resen t 450 9053 N present 10 9054 N p rese n t 50 9055 N p resent 150 9056 D present 1100 9165 N present-few 400 9167 N p rese n t 200 V e r tic a l d is t r ib u t io n and m igration. —This species was found in samples taken from surface w aters (ten m eters) to depths of eleven hundred m eters. There i s evidence th a t t h i s species i s p resen t through a very th ic k zone ranging from the surface to about eig h t hundred meters during the n ight and from two hundred m eters to eleven hundred meters (deepest sample) during the day. Table 30 i l l u s t r a t e s these depth d is t r ib u t io n s . Reproductive c y c le .--The reproductive inform ation obtained on V ib ilia armata i s d i f f i c u l t to in te r p r e t . Stephensen (191$) rep o rted fin d in g breeding females in January and February and from June through September and young during a l l seasons. His study was conducted in the M editerranean Sea. TABLE 3 0 .—Day and n ig h t depth d is t r ib u t io n s fo r V ib ilia armata based on the percentages of p o s itiv e samples No. No. P o sitiv e Percentage Depth (m) Hauls Hauls P o sitiv e Hauls Night 0- 50 4 3 75% 50- 100 2 2 100% 100- 200 7 5 70% 200- 300 4 3 75% 3 0 0- 400 6 5 82% 4 0 0- 500 2 2 100% 5 0 0- 600 7 2 30% 600- 700 2 1 50% 7 0 0- £00 1 1 100% £00- 900 1 0 9 0 0- 1100 3 0 0% Day 0- 50 2 0 0% 50- 100 2 0 0% 100- 200 2 0 O fo 200- 300 4 3 75% 3 0 0- 400 4 2 50% 4 0 0- 500 5 4 m 5 0 0- 600 5 5 100% 600- 700 4 2 700- £00 3 2 66% £00- 900 4 3 900- 1100 £ 7 88% P la te XII, Figure 25, i l l u s t r a t e s the percentages of mature females with ova and young throughout the year in th e Outer Santa Barbara Passage. There were no ovigerous females in the w inter and only a low, but c o n s is te n t, p e r centage throughout the r e s t of th e year. The presence of Figure 2 4 .--Seasonal v a ria tio n in mean size and size range fo r V ib ilia armata. Figure 2 5 .--Seasonal v a ria tio n in the percentage of in d iv id u a ls carrying ova and young. 96 PLATE XII size mm W W 24 100* 75 - 50 25 25 98 young in the brood pouches showed th a t the probable time of the re le a s e o f young was in the l a t e spring and ea rly summer. This re le a s e i s c o rre la te d with a drop in mean siz e and an extension of the lower lim it of the size range in the summer, in d ic a tin g the entrance of young in to the mature population (Figure 24). The follow ing l i s t of numbers per traw l hour shows an in c re a se in population d en sity in the la te summer and e a rly f a l l . Month No./Trawl Hour January 128 February no q u a n tita tiv e data March 32 A pril no q u a n tita tiv e data May 30 June 4 July 3 August 34 September 44 October 360 November 350 December 15 The reproductive and size data presented on V ib ilia armata are based on the observations and measurements of 1025 in d iv id u a ls . V ib ilia v i a t r i x B ovallius V ib ilia c a lif o r n ic a Holmes (1908), pp. 490-492, f i g s . 1-2. V ib ilia v i a t r i x , Stephensen (1918), pp. 41-43, f ig . 13; Chevreux e t Fage (1925), pp. 3&5-386, f i g . 390; P i r l o t (1929), pp. 95-96; Barnard, K. H. (1930), p. 403; P i r l o t (1930), pp. 10-11; Barnard, K. H. (1932), pp. 262-263; Shoemaker (1945), p. 234; Hurley (1956), p. 11. 99 Six hundred and f i f t y - e i g h t in d iv id u a ls of t h i s species were so rted from p in t a liq u o ts and many oth ers were recorded from q u a lita tiv e samples. Table 31 l i s t s the p o s itiv e s ta tio n s fo r V ib ilia v i a t r i x . TABLE 31*—S ta tio n l i s t and sample data fo r V ib ilia v i a t r i x Station Day- No. /Trawl No. night No./Pint Depth (m) Hour £0 l£ D 34 900 136 £024 D 247 37$ 9££ £025 N 24 522 96 £ 0 2 6 D 5$ 504 232 £027 D 12 46£ 4£ £029 N 3$ 666 152 £ 0 3 0 N 13 540 52 £031 N 4 540 16 £ 1 1 1 D 36 750 144 £ 1 1 4 D 2£ 650 112 £115 N 17 750 6£ £116 N 20 400 £0 £117 N 3$ 650 152 £ ll£ D 13 927 52 £120 D £ 945 32 £121 D 3 360 12 £123 N 2 360 £ £23£ D 7 975 2S £239 N 2 400 £ £ 2 4 0 N 3 300 12 £242 D 4 £60 16 £291 D 2 562 £ £292 N 5 170 20 £293 N 1 £5 4 £295 D 4 954 16 £296 D 2 500 £ #349 D 2 9 0 0 £ £350 D 3 3£5 12 B4 2S N 5 170 20 £430 D 1 £00 4 $433 N 3 300 12 £697 D 1 1000(plus) 4 S6 9S N 2 150 £ 100 TABLE 31— Continued S ta tio n No. Day- night N o./Pint Depth (m) No, /Trawl Hour $702 D 4 275 16 $711 D 2 490 $ $712 D 1 700 4 $716 N 1 425 4 $7$$ D 6 455 24 $795 D 2 770 $ $956 N p re se n t 15 $957 N present 50 $95S N p resen t 2$5 $961 D p rese n t 450 9053 N present 10 9054 N p rese n t 50 9055 N present 150 9059 D present 325 9165 N p rese n t 400 9349 N p rese n t 550 9350 D present 165 959$ D p rese n t 100 9599 D p resen t 50 9600 D present 20 Geographical d i s t r i b u t i o n .--B arnard, K. H. (1932), rep o rted the d is t r ib u t io n of V ib ilia v i a t r i x as the Mediterranean Sea and the A tla n tic , Indian, and E astern P a c ific Oceans. I t has been recorded from Point Loma, C a lifo rn ia , by Holmes (190$) and o f f southern C a lifo rn ia by Hurley (1956). V e rtic a l d is tr ib u tio n and m ig ra tio n . — Specimens of V ib ilia v i a t r i x were taken in traw ls ranging in depth from ten to eleven hundred m eters. In d iv id u a ls were also found asso c ia ted with salps a t the surface. 101 Table 32 i l l u s t r a t e s th e day and n ig h t depth d is tr ib u tio n s fo r t h i s sp ecies. I t appears th a t those in d iv id u a ls which liv e deep may move upwards during the night but the extent of t h i s m igration i s very small. TABLE 3 2 .—Day and n ig h t depth d is tr ib u tio n s fo r V ib ilia v i a t r i x based on th e percentages of p o s itiv e samples Depth (m) No. Hauls No. P o sitiv e Hauls Percentage P o sitiv e Hauls Night 0 - 50 4 4 100% 50- 100 2 1 50% 100- 200 7 4 57% 200- 300 4 3 15% 3 0 0- 400 6 4 66% 400- 500 2 2 100% 500- 600 7 1 14% 600- 700 2 2 100% 70 0- goo 1 1 100% goo- 900 1 0 0 % 900-1100 3 1 33% Day 0 - 50 2 2 100% $0- 100 2 1 50$ 100- 200 2 1 200- 300 4 1 25% 300- 400 4 . 4 100% 4 0 0- 500 5 4 go% 500- 600 5 4 go % 600- 700 4 2 50% 7 0 0 - goo 3 3 100% goo- 900 4 3 75 % - 900-1100 g 7 87% 102 Reproductive c y c le .--Stephensen (191S) reported specimens of V ib ilia v i a t r i x from the North A tla n tic in breeding condition during March and October. P la te X III, Figure 27, i l l u s t r a t e s the percentages of mature in d iv id u a ls carry in g ova and young throughout the study period. Ovigerous females were most abundant in the f a l l and a high percentage of females with young was noted in the w in ter. P la te X III, Figure 26, shows an expected drop in the mean siz e and an extension of the lower lim it of the size range during the summer. The follow ing l i s t of numbers per traw l hour shows an increase in density during the summer. Month No./Trawl Hour January 4.5 February no q u a n tita tiv e data March 0 A p ril no q u a n tita tiv e data May 4 June 3 July 17 August 95 September 9 October 10 November 4.# December 4.S Family Phronimidae Phronima se d e n ta ria (Forskal) Phronima s e d e n ta ria . Holmes (190S), p. 490; Stephensen (1924), pp. 114-121, f i g s . 50-51, chart 15; Chevreux et Page (1925), pp. 393-395, f ig . 396; P i r l o t (1929), Figure 2 6 .--Seasonal v a ria tio n in mean size and size range fo r V ib ilia v ia tr i x . Figure 2 7 .--S easonal v a ria tio n on the percentages of in d iv id u a ls carrying ova and young. 103 PLATE XIII 2 0 - 15 - size mm W 26 100- 75 - 50 - 25 - 2 7 105 pp. 110-112; Barnard, K. H. (1930), p. 422; P i r l o t (1930), pp. 12-14; Barnard, K. H. (1932), pp. 2£3-2£4; Thorsteinson (1945), p. 236; Hurley (1956), p. 16. Phronima sed en taria was one of the commonest species taken during t h i s study. A t o t a l of 575 in d iv id u a ls was c o lle c te d from p in t a liq u o ts and many o th e rs were recorded in q u a lita tiv e samples. Table 33 l i s t s the p o sitiv e s ta tio n s fo r P. se d en ta ria . TABLE 3 3 .--S ta tio n l i s t and sample data fo r Phronima se d en taria S ta tio n Day- No. Females/ No. M ales/ Depth No. /Trawl No. night P int P in t (m) Hour £024 D 10 0 37£ 40 £025 N 1 1 522 £ £026 D 7 6 504 52 £027 D 29 11 46£ 160 £029 N 7 7 666 56 £ 0 3 0 N 4 2 540 24 £031 N 3 4 540 2£ £111 D 11 13 750 96 £114 D 20 16 640 192 (12 damaged) £0 £115 N 15 5 750 £ 1 1 6 N 19 7 4 0 0 104 £117 N 13 6 650 76 £ ll£ D 12 6 927 72 £119 D 25 2 2££ 10£ £120 D 5 6 945 44 £121 D (134 specimens , few a d u lts , 360 536 many less than 10 mm) £122 N 4 0 945 16 £123 N 11 0 360 44 £23S D 4 3 975 2£ £239 N 2 0 4 0 0 £ £ 2 4 0 N 1 0 300 4 £242 D 2 0 £60 £ S243 D 3 2 600 20 106 TABLE 33— Continued S tatio n No. Day- night No. Females/ No P in t . Males/ Pint Depth (m) No./Trawl Hour 8291 D 1 0 562 4 3292 N 5 1 170 24 3293 N 13 2 85 60 3295 D 2 2 954 16 3296 D 6 1 500 23 3346 D 0 1 980 4 3347 N 1 0 387 4 #349 D 1 0 900 4 8350 D 11 2 385 52 3427 D 1 0 520 4 3423 N 12 0 170 48 3430 D 2 0 300 8 ■3433 N 1 0 300 4 3506 D 2 0 300 32 3503 du sk 2 0 425 16 3697 D 1 0 1000(plus ) 4 3693 N (1 damaged) 150 4 3702 D 4 0 275 16 3710 N (1 juvenile) 390 4 3711 D 4 1 490 20 3713 N 8 0 195 32 3717 N 1 0 80 4 3733 D 6 4 455 40 3739 N 22 0 190 88 3796 D 1 0 700 4 3953 N present 285 3960 D present 275 9055 N present 150 9059 D present 325 9167 N present 200 Geographical d i s t r i b u t i o n . - - Phronima se d e n ta ria i s known from the North A tla n tic , South A tla n tic , and Indo- P a c ific Oceans and the M editerranean Sea (Barnard, K. H., 1932). In the C a lifo rn ia area P. sed en ta ria has been rep o rted from Point Loma, North Coronado Islan d , Point 107 La J o lla , Santa C atalina Isla n d , and Monterey Bay (Holmes, 1908). Hurley (1956) a lso reported t h i s species from southern C alifo rn ia w aters. V e rtic a l d is t r ib u t io n and m ig ratio n . - - I t has been suggested in much of the e a rly l i t e r a t u r e th a t only the young of t h i s species were ever captured near the surface and th a t a d u lts were ty p ic a lly taken in deep tra w ls. This suggestion i s not supported by the data c o lle c te d in th is p resent study. The average size of the specimens taken from depths of le ss than 100 meters was 25 mm. Those in d i v id u a ls recovered from depths of less than 200 meters had an average length of 23 mm. Specimens from samples taken deeper than 200 meters averaged 24 m m in len g th . There was, then, no s ig n ific a n t d iffe re n c e in size between those in d iv id u a ls found in shallow and deep samples. No specimens were recovered in samples from depths of le s s than 80 m eters. There i s some evidence of v e r t i c a l movement towards the surface a t n ig h t. This a c t i v i t y appeared to be shown p rim arily by those in d iv id u a ls which were liv in g above four hundred meters during the day. Table 34 i l l u s t r a t e s t h i s a c t i v i t y as shown by comparing the percentages of p o s itiv e samples w ithin d iffe re n t depth ranges. I t appears t h a t the d ee p e r-liv in g members of the population may not engage in a v e r t i c a l m igration upwards during the n ig h t. 108 TABLE 3 4 .--Day and night depth d i s t r ib u t io n s for Phronima se d en ta ria based on the percentages o f p o s itiv e samples Depth (m) No. Hauls No. P o sitiv e Hauls Percentage P o sitiv e Hauls Night 0- 50 4 0 0$ 5 0- 100 2 2 100$ 100- 200 7 7 100$ 200- 300 4 2 50$ 300- 400 6 4 66$ 4 0 0- 500 2 0 0$ 5 0 0- 600 7 3 47$ 600- 700 2 2 100$ 700- BOO 1 1 100$ BOO- 900 1 0 0$ 900-1100 3 2 15% Day 0- 50 2 0 50- 100 2 0 100- 200 2 0 200- 300 4 4 300- 400 4 4 4 0 0- 500 5 4 500- 600 5 4 600- 700 4 2 700- BOO 3 2 B00- 900 4 2 900- 1100 B 6 0$ 100$ 100$ B O $ B0$ 5°$ 50$ 75$ Reproductive c y c le . —The rep o rted reproductive d ata are reviewed by Barnard, K. H. (1932), who in d ic ated th a t in the more Northern regions of i t s d i s t r i b u t i o n Phronima sed en ta ria has i t s h ig h e st reproductive a c t i v i t y during th e summer and autumn months. 109 P la te XIV, Figure 29, shows the percentages o f mature females carrying ova and young throughout the year. The peak of egg production was noted to occur in the summer. Since the young are c a rrie d fo r some time during t h e i r development on the inner w alls of the salp '’b a r r e ls ” in which t h i s species is known to liv e , and only a few of these b a r r e ls were c o lle c te d , the percentages fo r the presence o f young are probably in accu rate. The number of females per male showed a decrease during the period of ova production. This may in d ic a te death for the males a f te r copulation, although th e re i s no evidence fo r t h i s other than the above-mentioned decrease in number. Females/male Winter 10/1 Spring no males c o lle c te d Summer 2.4/1 F a ll 2.2/1 P late XIV, Figure 2$, shows a decrease in mean size for Phronima sed en ta ria during th e spring and f a l l and the appearance of a bimodal size d is t r ib u t io n during th ese tim es. A s ig n if ic a n t drop in the lower lim it of the size range was noted in the summer. The follow ing l i s t shows the v a ria tio n in number per traw l hour fo r those months of q u a n tita tiv e sampling. Figure 2 8. —Seasonal v a ria tio n in mean size and siz e range fo r Phronima s e n t a r i a . ? - no males c o lle c te d h o riz o n ta l bars in d ic a te modes Figure 2 9 .--S easonal v a ria tio n in the percentages o f mature females of P. sed en taria carrying ova and young. 110 1 PLATE XIV 4 0 -1 30- size mm 20- Su 28 100 50 112 Month No./Trawl Hour January 8 February no q u a n tita tiv e data March 3 A pril no q u a n tita tiv e .data May 3 June 8 July 12 August 40 September 31 October $ November 6 December 8 Although the time of the re le a s e of young from the brood pouches i s sp e c u la tiv e , the inform ation presented above in d ic a te s th a t reproductive a c tiv i ty is h ig h e st in th e summer and f a l l , concurring with Barnard’ s 1932 re p o rt. The reproductive and siz e data fo r Phronima seden- t a r i a are based on observations and measurements of th re e hundred in d iv id u a ls . Family Paraphronimidae Paraphronima g ra c ilu s Claus Paraphronima g r a c i l u s , Stephensen (1924), pp. 75-77; Chevreux e t Fage (1925), p. 391, f i g . 394; P i r l o t (1929), pp. 104-105; Barnard, K. H. (1932), p. 267; Hurley (1956), pp. 12-13. A t o t a l of 472 in d iv id u a ls of t h i s species was c o lle c te d from p in t a liq u o ts and many o th e rs were noted in c e rta in q u a l ita tiv e samples. Table 35 l i s t s the p o sitiv e s ta tio n s fo r Paraphronima g r a c i l u s . 113 TABLE 3 5 .—S tatio n l i s t and sample data fo r Paraphronima g ra c ilu s S ta tio n Day- No. Females/ No. Males/ Depth No./Trawl No. n ig h t P in t P in t (m) Hour 802 A D 0 8026 D 3 8027 D 0 8029 N 4 8030 N 1 8111 D 2 8114 D 8 8115 N 3 8116 N 13 8117 N 5 8118 D 4 8119 D 13 8120 D 3 8121 D 5 8123 N 2 8238 D 5 8239 N 30 8 240 N 42 8242 D 7 8243 D 3 8291 D 3 8292 N 23 8293 N 16 8295 D 7 8346 D 4 8347 N 3 8 349 D 2 8350 D 7 8427 D 4 8 4 2 8 N 14 8430 D 8 8433 N 2 8506 D 3 8508 dusk 4 8511 dusk 12 8512 N 8 8697 D 2 8698 N 2 8700 D 1 8702 D 1 8711 D 2 1 378 ' 4 3 504 24 1 468 4 2 666 24 1 540 8 6 750 32 2 650 40 1 750 16 7 400 80 1 650 24 4 927 64 7 288 80 5 945 32 4 360 36 6 360 32 6 975 44 5 400 140 18 300 240 5 860 48 1 600 16 6 562 36 12 170 140 21 85 148 10 945 68 1 980 20 2 387 20 2 900 16 0 385 28 3 520 28 1 170 60 2 800 40 0 300 8 4 300 112 6 425 80 5 275 272 2 230 40 2 1000(plus) 16 0 150 8 0 850 4 1 275 8 0 490 8 114 TABLE 35— Continued S ta tio n No. Day- night No. Females/ P int No. M ales/ P int Depth (m) No./Trawl Hour 8713 N 1 1 195 £ £716 N 1 0 425 4 8717 N 7 2 £0 36 8788 D 0 1 455 4 £ 7 8 9 N 7 5 190 4£ 8958 N p resen t 2£5 £961 D present 450 £964 N present in "up and down" catch with Foxton device fish e d at 1000 m Geographical d i s t r i b u t i o n . —Hurley (1956) reported the f i r s t record of Paraphronima g ra c ilu s from the west coast of North America. I t had been previously known from the A tla n tic and In d o -P acific Oceans and the M editerranean Sea (Barnard, K. H ., 1932). V e rtic a l d is t r ib u t io n and m ig ra tio n .--Specimens of Paraphronima g ra c ilu s were taken in traw ls ranging in depth from eig h ty to one thousand m eters. Diurnal m igration towards th e surface a t n ig h t was apparent. This species occurred in a g re a t number of the samples and in many cases contamination was suspected in some of th e p o s itiv e , deep nighttim e traw ls. The d iffe re n c e in numbers per traw l hour, however, suggest a movement towards the surface a t n ig h t. Given in Table 36 are the average numbers per traw l hour and th e percentages of p o s itiv e samples a t d if f e r e n t 115 depth ranges. The numbers per traw l hour are based only- on p o s itiv e samples. TABLE 3 6 . —Day and night records of number per traw l hour and percentages of p o s itiv e samples fo r Paraphronima g ra c ilu s taken in shallow and deep hauls Average N o./ Percentage of Depth (m) Trawl Hour P o sitiv e Samples Night 0- 4 0 0 72 83$ 4 0 0 -1 1 0 0 15 3 T/o Day 0 - 400 44 3 8% 4 0 0 -1 1 0 0 28 82% Reproductive c y c le .—Hurley ( 1 9 5 6) rep o rted a sin g le female with young in the brood pouch during th e month of August. P late XV, Figure 31, shows the v a r ia tio n in the percentages of mature females carry in g ova and young in the brood pouches throughout the study period. Ovigerous females were most prevalent in the f a l l and th e highest percentage of females with young was noted in the summer. Young were ap p aren tly re le a se d from the p aren ts in the f a l l and Figure 30 shows a corresponding drop in mean siz e in the f a l l and the w inter. There was, however, an extension Figure 30.— Seasonal v a ria tio n in mean siz e and siz e range fo r Paraphronima g r a c i l u s . Figure 3 1 .--Seasonal v a ria tio n in the percentages of mature females o f P. g ra c ilu s carrying ova and young. 116 PLATE XV f 15- size mm ,i w w 30 100- 25 - 118 of the lower lim it of the siz e range during the summer. There was some v a r ia tio n in the r a t i o between the number of females per male. Females/male Winter 4/1 Spring 1.6/1 Summer 1.8/1 F a ll 2/1 There was also an in crease in the d e n sity of the population during the f a l l and w inter months. Month No./Trawl Hour January 25 February no q u a n tita tiv e data March 32 A pril no q u a n tita tiv e data May 8 June 6 July 6 August 12 September 20 October 1 + 8 November 32 December 12 The above inform ation on reproduction and siz e for Paraphronima g ra c ilu s i s based on the observations and measurements of four hundred in d iv id u a ls . Paraphronima c ra ssip e s Claus Paraphronima c r a s s ip e s . Stephensen ( 1 9 2 4), pp. 77-78; Chevreux e t Fage (1925), pp. 390-391, f ig s . 393-394; P i r l o t (1929), pp. 105-106; Barnard, K. H. (1930), pp. 409-410; Barnard, K. H. (1932), pp. 267-268; Shoemaker (1945), p. 234; Hurley (1956), p. 1 3 . 119 Nine hundred twenty-two in d iv id u a ls of Paraphronima c ra s sip e s were sorted from p in t a liq u o ts and many o th e rs were taken from some of the q u a lita tiv e samples. Table 37 l i s t s the p o sitiv e s ta tio n s fo r t h i s species. TABLE 3 7 .--S ta tio n l i s t and sample data for Paraphronima crassip es S ta tio n No. Day- night No. Females/ No P in t . M ales/ Pint Depth (m) No/Trawl Hour 8024 D 8 2 378 40 8025 N 4 3 522 28 8 0 2 6 D 5 2 504 28 8027 D 6 7 468 52 8 029 N 5 6 666 44 8 0 3 0 N 5 3 540 32 8031 N 2 2 540 16 8 1 1 1 D 5 6 750 44 8114 D 14 13 650 108 8115 N 17 3 750 80 8 1 1 6 N 42 17 400 236 8117 N 7 6 650 52 8 1 1 8 D 11 16 927 68 8119 D 2 8 288 40 8120 D 5 3 945 32 8121 D 6 1 360 28 8 1 2 2 N 0 1 945 4 8123 N 4 5 360 36 8 2 3 8 D 8 6 975 56 8239 N 24 29 400 212 8240 N 54 44 300 396 8242 D 7 5 860 48 8291 D 1 7 562 32 8292 N 9 20 170 116 8293 N 1 2 #5 12 8295 D 10 3 954 52 8296 D 10 1 500 44 8298 N prese n t 475 8346 D 1 0 980 4 8347 N 9 6 387 60 8349 D 5 7 900 48 8350 D 8 5 385 52 TABLE 37— Continued 120 S tatio n No. Day- n ight No. Females/ No P int . Males/ Pint Depth (m) No./Trawl Hour 342 7 D 13 10 520 92 3423 N 97 93 170 760 3430 D 12 6 800 72 3433 N 13 1 300 56 3506 D 68 1 300 1104 3503 dusk 7 4 425 88 3511 dusk 3 3 275 96 3512 N 7 1 230 32 3697 D 2 2 ■ 1 0 0 0(plus ) 16 3693 N 5 1 150 24 3700 D 1 2 8 5 0 12 3702 D 8 0 275 32 3711 D 2 1 490 12 3712 D 2 2 700 16 8713 N 2 1 195 12 8 7 1 6 N 0 1 425 4 8717 N 2 9 80 44 8788 D 4 0 455 16 8958 N present 285 8961 D present 450 8 9 6 4 N (present in ”up and downrt catch with Foxton device fish ed at 1000 m) 9059 D present 325 Geographical d i s t r i b u t i o n . — Barnard, K. H. (1932), reported the d is t r ib u t io n of Paraphronima c ra ssip e s as the M editerranean Sea and the A tla n tic and P a c ific Oceans. Hurley (1956) recorded th i s species from o ff the coast of southern C a lifo rn ia . V e r tic a l d is tr ib u tio n and m ig ra tio n . —Specimens of P. c ra s sip e s were found in samples ranging in depth from eighty to one thousand m eters. As in P. g r a c i l u s , a 121 movement towards the surface during the nig h t was apparent. This a c t i v i t y is i l l u s t r a t e d in Table TABLE 3&*—Day and night depth d is tr ib u tio n of Paraphronima c ra ssip e s based on the percentages of p o s itiv e samples Percentage P o sitiv e Percentage P o sitiv e Depth Range (m) Day Samples Night Samples 0- 200 0% 50% 200-1100 15% 65% Reproductive c y c le . --Hurley (1956) reported specimens of t h i s species c o lle c te d in July and August carrying ova or young in th e ir brood pouches. These obser v atio n s were made during a study o ff the southern C a lif o rnia coast but on fewer in d iv id u a ls than were taken in t h i s present work. P late XVI, Figure 33, i l l u s t r a t e s the percentages of mature females carrying ova and young throughout the study period. The highest frequency of ovigerous females was noted in the f a l l months and was followed by a high p e r centage of females with young during the w inter and sp rin g . Young were apparently re le a se d from the p aren ts in the summer and f a l l months. Figure 32 shows a corresponding drop in the mean size for these periods and an extension of the lower lim it of th e siz e range during th e f a l l . Figure 3 2 .—Seasonal v a ria tio n in mean size and siz e range fo r Paraphronima c ra s s ip e s . Figure 33*—Seasonal v a r ia tio n in the percentages of mature females o f P. cra ssip e s carry in g ova and young. 122 Csta-t- PLATE XVI 40- 30- size mm 20 W W 32 50 - 25 - w 33 124 The v a ria tio n in the r a t i o between the number of females per male showed a s ig n if ic a n t a sso c ia tio n with the presence of ova in th e brood pouches. There was also a r i s e in the number per tra w l hour during the f a l l and w inter. c ra s s ip e s are based on observations and measurements of th ree hundred f i f t y in d iv id u a ls . Family Scinidae Although r a th e r common members of the mid-water fauna, in d iv id u a ls of the genus Scina were d i f f i c u l t to id e n tif y . Hurley (1956) o ffe rs a key to the species of t h i s genus. This i s not intended as a system atic re v is io n , nor as an opposition to previous taxonomic accounts. The Females/male Winter Spring Summer F a ll Month No./Trawl Hour January February March A p ril May June July August September October November December 72 no Quantitative data 70 no quantitative data 12 8 8 32 24 74 24 32 The reproductive and size data fo r Paraphronima 125 follow ing statem ents merely suggest the need fo r a d d itio n a l work and in d ic a te th a t the id e n tif ic a tio n s presented in th i s paper are in p a rt dubious. Although considered a diag n o stic c h a r a c te r i s tic , the s e rra tio n on the bases of the f i f t h p a ir of peraeopods are su b ject to much v a ria tio n in the specimens c o lle c te d . The peraeopodal te e th of the specimens presented in t h i s paper as Scina tu llb e r g i are very sim ila r to those p ic tu re d by Wagler (1926) fo r S. r a t t r a y i . The f i r s t antennae, how ever, are as long as the peraeon and the pleon combined which, according to Hurley (1956), excludes the p o s s i b i l i t y of th ese in d iv id u als being S. r a t t r a y i . The d iffe re n c e s in size ranges recorded in t h i s and o ther stu d ies add to the d i f f i c u l t y of p o s itiv e i d e n tif ic a tio n . Scina nana V/agler Scina nana Wagler (1926), pp. 393-395, f ig . 37; Hurley (1956), p. 9. Four small (3 mm) specimens of t h i s species were taken from S ta tio n 8119; a daytime haul a t 288 m eters. Geographical d i s t r i b u t i o n . —The f i r s t record of t h i s species from southern C a lifo rn ia waters was reported by Hurley (1956) who c o lle c te d one 4 m m female. V e rtic a l d is t r ib u t io n and m ig ra tio n . —The single specimen taken by Hurley (1956) was captured during an open net tow a t 1280 meters during the daytime. The four 126 in d iv id u als c o lle c te d in t h i s present study were captured a t a depth of 288 meters during a daytime tra w l. I t i s im possible to suggest any d e f in it e m igratory p a tte rn on the b a sis of so few p o sitiv e samples. Reproductive c y c le .--Two of the specimens taken in t h i s study were ovigerous females. These in d iv id u a ls were captured during the month of September. Scina tu ll b e r g i (Bovallius) Scina p a c i f i c a , P ir l o t (1929), p. #5. Scina t u l l b e r g i , V/agler (1926), pp. 3$4-390, f ig s . 34-35; Barnard, K. H. (1932), pp. 261-262; Shoemaker (1945), p. 232; Hurley (1956), p. 9. A t o t a l of t h i r t y - t h r e e in d iv id u a ls was recovered from p in t a liq u o ts throughout th is study; none were noted in any of th e q u a lita tiv e samples. Table 39 l i s t s the p o s itiv e s ta tio n s and c e rta in sample data fo r Scina t u l l b e r g i . Geographical d i s t r i b u t i o n . —Barnard, K. H. (1932), gives the d is tr ib u tio n of t h i s species as the M editerranean Sea, the A tla n tic Ocean from about 54°N to 31°S, the P a c ific Ocean o ff Nicaragua and Cape Horn, and the Indian Ocean. Hurley (1956) t e n ta t iv e ly i d e n tif ie d one specimen as S. t u l l b e r g i from h is c o lle c tio n s o f f southern C a lifo rn ia . 127 TABLE 3 9 .—S ta tio n l i s t and sample data for Scina tu llb e r g i. S tation No, Day- night No. Females/ Pint S ize No. M ales/ Pint S ize Depth <») 3031 N 1 13 m m 0 __ 540 3240 N 0 — 1 13 m m 300 3292 N 0 — 2 14,13 m m 170 3349 D 2 17,19 m m 0 - - 900 3427 D 1 13 m m 1 13 m m 520 3433 N 1 12 m m 2 11,14 m m 300 3503 dusk 5 10-17 m m 1 lo m m 425 3702 D 2 10,19 r a m 0 --- 275 3711 D 7 10-16 m m 0 — — 490 3712 D (two damaged) 700 3733 D 4 13-20 m m 2 12,13 m m 455 3795 D 1 14 m m 0 — — 770 V e r tic a l d istr ib u tio n and m igration. — In d ividu als o f t h is sp ec ies were taken in samples ranging in depth from one hundred seventy to nine hundred m eters. There was some evidence o f v e r t ic a l movement in to shallower water during the dark hours. Reproductive c y c le . —Ovigerous fem ales were collected in January, March, and July. Young were noted in the brood pouches o f some fem ales in August. Scina b o r e a lis (Sars) Scina b o r e a lis . Stephensen (1913), pp. 30-31; Chevreux et Fage (1925), pp. 330-332, f i g . 337; P ir lo t (1929), pp. 73-79; Barnard, K. H. (1932), p. 260; Thorsteinson (1941), pp. 36-37, p i. 3, f i g . 73; Shoemaker (1945), p. 230; Hurley (1956), pp. 3 -9 . 126 This sp ec ies was the most common member o f the genus Scina th at was taken during the study. S ix ty -e ig h t in d i vid u als were c o lle c te d in p in t a liq u o ts. Table 40 l i s t s the p o s itiv e sta tio n s for S. b o r e a lis . TABLE 4 0 .—S tation l i s t and sample data for Scina b o r e a lis . S tation No. Day- night No. Females/ Pint S ize No. M ales/ Pint S ize Depth (m) 3018 D 1 7 m m 0 900 8024 D 1 9 m m 0 — — 378 8025 N (two damaged) 522 8026 D 7 5-8 m m 0 504 8027 D 0 — — 1 9 m m 468 8029 N 1 8 m m 0 — 666 8030 N 7 5-9 m m 3 6-10 m m 540 8111 D 4 8-9 m m 1 9 m m 750 8114 D 1 9 m m 0 — 650 8115 N 2 8-9 m m 0 — 750 8116 N 9 5-8 m m 1 5 m m 400 8117 N 5 6-8 m m 2 6-9 m m 650 8118 D 3 7-8 m m 1 8 m m 927 8238 D 2 6-7 m m 0 — — 975 8242 D 2 7 m m 0 860 8296 D 1 7 m m 0 — — 500 8427 D 1 6 m m 1 8 m m 520 8428 N 1 8 m m 0 — 170 $430 D 0 1 7 m m 800 8512 N 1 8 m m 0 — 230 8716 N 1 7 m m 2 4,5 m m 425 ( ju v e n iles) 8788 D 5 6-9 m m 0 455 Geographical d is t r ib u t io n . —Shoemaker (1945) gave the d istr ib u tio n o f Scina b o r e a lis to include the North and South A tla n tic , the North and South P a c ific , and the Indian Oceans, the Mediterranean Sea, the Gulf of Alaska, and the 129 A rctic and A ntarctic Oceans. Thorsteinson (1941) and Hurley (1956) reported t h is sp ec ies from the west coast o f North America; H urley’ s record was from southern C a lifo rn ia . V e r tic a l d istr ib u tio n and m igration . —In d ivid u als of t h is sp ecies were captured in traw ls taken at depths rang ing from 170 to 975 m eters. There was some evidence of a v e r t ic a l movement to shallow er water during the night but the data are too scant to be con clu sive. Reproductive c y c le . —Ovigerous fem ales were captured during the months o f January and August, and young were present in the brood pouches during August. No other reproductive inform ation i s a v a ila b le for Scina b o r e a lis . Q u a lita tiv e Observations on Several S ta tio n s From the Waters o f the San Pedro Channel S ixteen s ta tio n s were se le c te d from the many samples taken in the region o f the San Pedro Channel. The complete data fo r th ese s ta tio n s are given in Appendix I I . For referen ce purposes the depth o f each o f th ese traw ls and the day-night inform ation are presented in Table 41. Presented here are th ose sp ec ies o f amphipods taken from a rough so rtin g o f the samples a sso c ia ted w ith the sta tio n s l i s t e d in Table 41. 130 TABLE 4 1 .—S ta tio n l i s t for q u a lita tiv e samples from the San Pedro Channel S tation No. Day-night Depth (m) 7221 D 815 7279 D 675 7281 N 675 7325 D 680 7371 D 800 7374 N 910 7388 D 600 7389 D 650 7391 N 550 8235 D 375 8236 D 520 8309 N 375 8310 N 150 8311 N 50 8312 N 784 8521 D 675 Suborder Gammaridea Family L ysianassidae Paracallisom a coecus (Holmes) This sp ec ies was only found in two s ta tio n s , 7281 and 7279. Both samples were at 675 m eters, one during the day and one during the n igh t. Cyphocaris anonyx Boeck I t i s in te r e s tin g to note th at the only th ree s ta tio n s in which th is sp ec ies was found were sampled at th e same depth. These s ta tio n s were 7281, 7325, and 8521. Two of th ese samples were from a depth o f 675 meters and 131 the th ird was from a depth of 680 m eters. These depths coincid e approximately with the recorded upper depth lim it fo r t h i s sp ec ies in the Santa C atalina area. Cyphocaris rich ard i Chevreux A few in d iv id u a ls o f th is sp ec ies were recovered from s ta tio n s 7374 and 8521, both r e la t iv e ly deep samples. This sp e c ie s was not as abundant, even at great depths, in the San Pedro Channel as i t was in the C atalina area. Orchomenella Members o f t h is genus were found only in sta tio n 8312, and in very low abundance. Suborder Hyperiidea Family Pronoidea Eupronoe minuta Claus This sp ec ies was c o lle c te d from four o f the San Pedro samples. In d ivid u als were very abundant in s ta tio n s 8310 and 8311, both shallow nighttim e s ta tio n s . They were present in low numbers in sta tio n s 7221 and 8309, the former being a very deep daytime tow and the la t t e r a shallow n ight sample. E. minuta was abundant near the sur face in the samples from the San Pedro area and probably m aintains a sim ila r v e r t ic a l d is tr ib u tio n a l pattern as was recorded in the Catalina area. 132 Family Phrosinidae Primno macropa Guerin This sp ec ies was taken in f iv e o f the samples from the San Pedro Channel. I t was abundant in s ta tio n s S310 and S311, the two shallow nighttim e tra w ls, and p resen t, but l e s s abundant, in s ta tio n s 7221, S235, and S309. This sp ecies apparently undergoes a v e r t ic a l movement towards the surface at n ig h t. This a c t iv it y was a lso recorded for Primno macropa in the Santa Catalina study area. Family Cystisomidae Cystisoma f a b r ic ii Stebbing In d ivid u als o f t h is sp ec ies were taken from the fo llo w in g samples: 7221, 7279, 7391, 73SS, and 8235. From four to seven specimens were taken in a rough so rtin g of each o f these s t a tio n s . They were more abundant in the San Pedro Channel m aterial than in the C atalina samples. The depth range fo r t h is sp ecies according to the p o s itiv e samples was about 375 to 815 m eters, as compared to 275 to 1000 meters in the Catalina area. Cystisoma pellucidum (Suhn) This sp ecies o f Cystisoma was recovered from only two o f the San Pedro s t a tio n s , 7325 and 8309. The former was a daytime traw l at 680 m eters and the la t t e r a n ig h t time sample from 375 m eters. Due to the sm all number o f 133 p o s itiv e samples no conclusions are drawn regarding the v e r t ic a l d istr ib u tio n o f t h is sp ec ies but i t i s probably sim ila r to C. f a b r i c i i . Family Qxycephalidae S tr e e ts ia pronoides B ovalliu s This sp ec ies was abundant in sta tio n s 7221, #235, and 8309 and was present in sm all numbers in s ta tio n s 7279 and 7374. The presence o f S. pronoides in sta tio n 7374 (a deep, nighttim e sample) may have been the r e s u lt o f con tam ination from shallower depths as the net was being lowered or ra ise d . Only one in d iv id u a l was noted in t h is s ta tio n . Although t h i s sp e c ie s was not taken in the very shallow n ig h t samples (13310 and #311), there i s evidence o f v e r t ic a l m igration towards the surface at n igh t. I t did not appear to migrate as far upwards as was noted in the C atalina area but t h is may be due to the sm all number o f samples analyzed. The v e r t ic a l range o f S tr e e ts ia pronoides in the San Pedro Channel was noted to be from 375 to 315 meters (again the night record from 910 meters may have been a r e s u lt o f contam ination). Family Hyperiidae Hyperia galba (Montague) Hyperia galba was abundant in s ta tio n s 323 5 > 3236, 3309, and 3310 and was present in sm aller numbers in 134 sta tio n s 73##, #312, and #521. There i s convincing evidence o f v e r t ic a l movement to shallow water during the dark hours. I t appears, however, that H. galba has a narrower v e r t ic a l range in th e San Pedro area than was noted over the C atalina Basin. A range o f from 150 to 675 meters was recorded from the San Pedro samples; a sin g le specimen was taken from sta tio n S312 (7#4 m eters, at night) but was probably the r e s u lt o f contamination from upper le v e ls . In the C atalina area a v e r t ic a l range o f from #5 to 1000 meters was noted. Females with young in th e ir brood pouches were noted in sta tio n #310, a November s ta tio n . Although i t i s impos s ib le to make s ig n if ic a n t comparisons on the b a sis o f t h is s in g le ob servation , i t should be noted that the h igh est percentage o f fem ales with young in the C atalina m aterial was in the spring and a very low percentage was recorded in the f a l l . Family V ib iliid a e V ib ilia armata B o v a lliu s In d iv id u a ls o f t h is sp e c ie s were recorded from the fo llow in g s ta tio n s in great abundance: 7221, £236, £309, £310, and #311. The sp e c ie s was present in sm all numbers in s ta tio n s 7374, #312, and £521. 135 There i s some evidence o f a v e r t ic a l m igration upwards at n igh t. Being such an abundant sp ecies i t i s q uite p o ssib le that i t s occurrence in some o f the deep nighttim e sta tio n s was the r e s u lt o f contamination from shallow er depths. V ib ilia v ia t r ix B ovalliu s V ib ilia v ia t r ix was abundant in the fo llow in g s ta tio n s: #2 3 6, 8309, 8310, and 8311. I t was present in sm aller numbers in sta tio n s 7221, 7371, and 7388. Since in d iv id u a ls were most abundant in the shallow night samples i t i s probable th a t there was some massing of the population near the surface during the dark hours. Family Phronimidae Phronima sedentaria (ForskSl) This was one o f the most common m igrating sp ec ies taken from the San Pedro Channel samples. I t was abundant in s ta tio n s 7221, 7388, 8235, 8236, 8309, 8310, and #311. I t was present in sm all numbers in sta tio n 7389. A sim ila r m igratory pattern was displayed by Phronima sedentaria in both o f the study areas. Young were noted attached to the inner w a lls o f the "barrel" houses during the month o f August, corresponding to the suggested breeding period for the Santa Catalina population. Family Paraphronimidae Paraphronima g r a c ilu s Claus This sp ec ies was recorded as abundant in sta tio n s 7221, 8235, and 8309. I t was present in sm aller numbers in sta tio n s 7279, 7374, and 8310. Although there i s some evidence o f v e r t ic a l m igration, th is sp e c ie s was not taken in the very shallow nighttim e samples over the San Pedro Basin, as i t had been in the Catalina area. I t appears that the upper lim it o f the migratory range i s shallow er in the waters over the deeper basin than i t i s in the San Pedro Channel. No ad d itio n a l data were obtained regarding the reproductive a c t iv it y o f Paraphronima g r a c ilu s . Paraphronima cr a ssip es Claus This sp ec ies displayed about the same v e r t ic a l d istr ib u tio n as did P. g r a c ilu s . I t was abundant in s t a tio n s 7221, 8235, and 8309 and present in s ta tio n 7325. Again there i s evidence that the magnitude o f the upward movement during the n ight i s not as great in the waters o f the San Pedro Channel as i t i s over the Santa C atalina Basin. No a d d itio n a l reproductive inform ation was obtained from the m a teria ls in the San Pedro samples. 137 Family Scinidae Scina tu llb e r g i B ovalliu s This sp ecies was taken in small numbers from sta tio n s 7221, 7279, and 7371 in the San Pedro area. A ll three o f th ese sta tio n s were deep, daytime traw ls. Scina b o r e a lis (Sars) This sp ec ies was c o lle c te d from a sin g le s ta tio n , 7221; a deep, daytime traw l. A Comparison o f the Outer Santa Barbara Passage and the San Pedro M aterials Although only a few q u a lita tiv e samples were examined from the San Pedro Channel area, some remarks comparing i t s amphipod fauna with that o f the Outer Santa Barbara Passage can be made. Faunal Composition I t appears th at the sp ec ies composition o f the two study areas are very sim ila r. The greater number o f sp e c ie s noted in the waters over the deeper basin i s prob ably a r e s u lt o f more ex ten siv e sampling in th at area. None o f the C atalina sp ecies were c o n sis te n tly taken so deep as to suggest th e ir exclu sion from the San Pedro region because o f depth. Most o f the sp ec ies c o lle c te d only in the C atalina area were r e la t iv e ly uncommon forms 138 and would most lik e ly be captured upon more exten sive study o f the San Pedro samples. V er tic a l D istrib u tio n and Migration For those sp ecies which were c o lle c te d in both o f the study areas, the h ab its o f m igration o f the two popula tio n s were sim ila r . In the cases o f Cystisoma spp. . S tr e e ts ia p ron oid es. Hyperia g a lb a . and Paraphronima spp. , the v e r t ic a l d ista n c es through which the in d iv id u a ls migrated were s ig n if ic a n t ly l e s s in the waters o f the San Pedro Channel than in the Outer Santa Barbara Passage. The depth ranges were a lso narrower in the shallower study area. The s ig n ific a n c e s o f th ese lim ita tio n s in the San Pedro region are sp ecu la tiv e but probably concern the c h a r a c te r is tic s o f th e basin w aters. I t appears, then, th a t there i s a narrowing o f the depth and migratory ranges in the shallower study area and not an elim in ation of d e e p -liv in g sp e c ie s. Reproductive Cycles Although very l i t t l e data were obtained regarding the reproductive a c t iv it y of the amphipods in the San Pedro region , that inform ation which was c o lle c te d su ggests that the breeding seasons for most sp ecies liv in g in both areas coin cid e. CHAPTER I I I DISCUSSION S pecies Composition From the data presented in th is paper i t can be seen th a t the lo c a l mid-water amphipod fauna i s made up prima r i l y of hyperiid s with only a few sp ecies o f gamraarids. A ll members o f the la t t e r group are e s s e n t ia lly d e e p -liv in g forms th at do not occur near the su rface. Those sp ecies which were taken in more than 30 per cent o f the samples were: Hyperiidea Eupronoe minuta Hyperia galba Paraphronima cra ssip es Paraphronima g r a c ilu s Phronima sedentaria Primno macropa Scina b o r e a lis S tr e e ts ia pronoides V ib ilia armata V ib ilia v ia t r ix A dd itional sp e c ie s, occurring in le s s than 30 per cent o f the samples, were: Gammaridea Cyphocaris anonyx Cyphocaris rich ard i Orchomenella spp. 139 140 Hyperiidea P la ty sc e lu s serratu lu s Cystisoma f a b r ic ii Cystisoma pellucidum Calamorhynchus rig id u s Oxycephalus cla u si Hyperia sp in igera Hyperia b en galensis Scina tu llb e r g i (?) Scina nana (?) Population S ize The abundance o f many o f the amphipod sp ecies varied g r e a tly w ith depth, time of day, and seasonal con d itio n s. P la te XVII, Figure 34, il l u s t r a t e s the seasonal v a ria tio n in the t o t a l amphipod population based on the calcu lated numbers per traw l hour. Since sampling throughout the year varied in the number o f samples taken at d iffe r e n t depths and times the valu es shown in Figure 34 are probably some what d isto r te d . The c y c lic flu c tu a tio n s are obvious, how ever, and o ffe r a general p ictu re o f the changes in population d en sity . The high numbers o f amphipods c o lle c te d in the la t e siimmer and early f a l l are correlated with the breeding seasons as i s discussed la te r in t h is chapter. Geographical D istrib u tion From analyses o f the geographical d is tr ib u tio n s given in the in d iv id u a l sp ecies accounts, i t can be seen Gammaridea Eurythenes obesus Paracallisom a coecus Rhachotropis natator Figure 3 4 .—Seasonal v a ria tio n in number per hour traw ling time for the t o t a l amphipod population. 141 PLATE XVII 150 - 50 - W F W Su 34 143 that the lo c a l amphipod fauna does not represent any s p e c ific geographic region . On the contrary, many o f the sp ec ies studied here e x h ib it rather discontinuous d is tr ib u tio n s as reported by previous workers. Many o f th ese spe c ie s w i l l probably have th e ir geographic ranges extended by the elim in a tio n o f d ic o n tin u itie s with a more complete sampling o f the w orld’s oceans. Two new records have been esta b lish ed during t h is present study: Calamorhynchus r ig id u s : New to the C aliforn ia coast and p o ssib ly the f i r s t P a c ific record, depending upon i t s taxonomi c statu s . Oxycephalus c l a u s i : New to the C aliforn ia co a st. A ll of the other sp ecies reported on in t h is paper have been recorded p reviou sly from lo c a l w aters. V e r tic a l D istrib u tio n and Migration On the b a sis o f v e r t ic a l d is tr ib u tio n , one can separate the mid-water amphipods in to two gen eral c a te g o r ie s. The members of the Suborder Gammaridea are p r i m arily d e e p -liv in g forms with th e exception of Cyphocaris anonyx, which was o cc a sio n a lly c o lle c te d at depths o f l e s s than four hundred m eters. The hyperiids are m ostly m igrat ing forms, being taken in samples from near the surface to the depth o f the deepest samples (eleven hundred m eters). 144 This group was most abundant at depths o f le s s than seven hundred m eters. From a n a ly sis o f the upper daytime lim its and the upper nighttim e lim its o f many hyperiid sp ec ies i t can be seen th at certa in ones m igrate minimum d ista n ces of two hundred m eters. For most sp ecies the upper lim it o f th e ir m igration i s esta b lish ed by the therm ocline. The therm ocline appar en tly presen ts a temperature b arrier through which only a few sp ec ies are able to p en etrate. This in a b i lit y to cross the therm ocline was apparent even in the w inter months when the temperature gradient was very s lig h t . Table 42 shows the common sp ec ies taken above and below f i f t y meters for rep resen ta tiv e months o f the year. From Table 42 i t can be seen th at th e seasonal v a ria tio n in therm ocline in te n s ity had l i t t l e e f fe c t on the v e r t i c a l d istr ib u tio n o f the amphipods. Most o f the sp ec ies are simply r e s tr ic te d to depths below that o f the therm ocline. Only four sp ecies were noted to penetrate the therm ocline barrier and only members o f the genus V ib ilia were c o n s is te n tly found in abundance above f i f t y m eters. Eupronoe minuta was very abundant between f i f t y and one hundred m eters. I t was abundant in a sin g le sample at f i f t y meters but was never taken above th at depth. S tr e e ts ia pronoides was present in low numbers in two traw ls a t depths o f f i f t y meters or le s s . 145 TABLE 4 2 .—Species composition above and below 50 meters during the w inter and the summer December, January, February 0-50 meters 50-200 meters V ib ilia armata Phronima sedentaria V. v ia t r ix Hyperia galba S tr e e ts ia pronoides Paraphronima cr a ssip es Paraphronima g r a c ilu s Eupronoe rainuta Primno macropa V ib ilia armata V. v ia t r ix S tr e e ts ia pronoides A pril through October 0-50 meters 50-200 meters V ib ilia armata Phronima sedentaria V. v ia t r ix Paraphronima cra ssip es Eupronoe minuta Paraphronima g ra c ilu s Eupronoe minuta Primno macropa V ib ilia armata V. v ia t r ix S tr e e ts ia pronoides The h a lo c lin e did not appear to o ffe r a b arrier to the v e r t ic a l movements o f any o f the amphipods stud ied. Low concentrations o f oxygen presented no s ig n ific a n t e f f e c t s on the q u a n titie s o f organisms c o l le c te d . I t i s in te r e s tin g to note that some o f the most productive samples were from depths o f greater than f iv e hundred meters and in a region o f very low oxygen content. 146 The paucity o f h yperiid s below s i l l depth i s d i f f i c u l t to exp lain . I t may be th at a more in ten se sam p lin g o f the basin waters would produce more in d iv id u a ls or th a t the hydrographic con d ition s o f th at southern water r e s t r ic t many sp ecies from resid in g th ere. Due to a lack of hydrographic data from deep waters the r e s t r ic t io n o f the gammarids to depths grea ter than fiv e hundred meters cannot be correlated with oceanographic con d ition s. C losely a sso c ia te d , o f course, with the v e r t ic a l d istr ib u tio n o f certain amphipods are th e ir p atterns o f v e r t i c a l movement. Certain patterns o f v e r tic a l m igration were apparent w ithin d iffe r e n t sp e c ie s. F u ll inform ation i s presented in the in d iv id u a l sp ec ies accounts, but d is cussed here are a few examples which o f fe r the c le a r e st rep resen ta tio n s o f the migratory p attern s observed. Rhachotropis natator This sp ecies was recorded as m igrating v e r t ic a lly w ithin a depth range o f from s ix hundred to eleven hundred meters (the deepest samples taken). A nalysis o f daytime samples in d icated th a t in d iv id u a ls of t h is sp ec ies were o f about uniform d en sity throughout the s ix hundred to eleven hundred meter depth range. During the night they were only captured at depths of greater than nine hundred m eters. 147 P la te XVIII, Figure 35, i l l u s t r a t e s t h is diurnal v a ria tio n in depth d istr ib u tio n . Indicated here i s a migratory movement in to shallower water during the dayligh t hours and a r e tr e a t in to deeper water at n ig h t. The fa c to r s in flu en cin g t h is type o f deep- water m igration are unclear. Since the la s t p erceivab le lig h t i s lo s t at about s i x hundred ten m eters (D ietz, 1962) and the temperature i s r e la t iv e ly sta b le at great depths, lig h t and temperature are certa in ly not fa c to r s . The v e r tic a l movements of Rhachotropis natator may, in f a c t , represent an endogenous rhythm and th erefore are independ ent o f environmental v a r ia tio n s . The advantage to r is in g during the dayligh t hours may be to feed on those organisms which are moving downwards at th at tim e. This suggestion i s sp ecu la tiv e and no data are a v a ila b le to support i t other than the migratory pattern i t s e l f . S tr e e ts ia pronoides During the d ayligh t hours th is sp ecies was r e s tr ic te d to depths greater than two hundred meters and w hile i t was most abundant between two hundred and four hundred m eters, in d iv id u a ls were recovered from samples taken as deep as one thousand m eters. During the n ig h t, however, S tr e e ts ia pronoides was abundant in more than 50 per cent o f the shallow samples from depths o f le s s than three hundred m eters. This v a r ia tio n in depth ranges Figure 3 5 .—Day and night depth d istr ib u tio n o f Rhachotropis natator based on the percentages o f p o s itiv e samples at various depths. Bar width o f one inch equals 100 per cent p o s itiv e samples. 148 PLATE XVIII R. natator 200- 400 - Dm 600 - 800 - 1000 - day night 35 between day and n ight in d ic a te s a v e r t ic a l movement towards the surface during the dark hours. As shown in P la te XIX, Figure 36, S. pronoides was a lso captured in some .of the deeper nighttim e samples. This discontinuous v e r t ic a l d istr ib u tio n during the night may be th e r e s u lt o f the a ctio n o f several fa c to r s . The p o s s ib ili t y e x is ts that only part o f the population m igrates upwards at n ight w hile some in d iv id u a ls remain in deeper w ater. No d iffe r e n c e s were noted in s iz e , sex, reproductive con d ition, etc., between the "shallow" and the "deep" populations. Because o f a lack o f id e n t ifia b le d iffer en ce s between the two groups i t i s d i f f i c u l t to su b sta n tia te the occurrence o f a m igrating and a non-m igrating population. A second p o s s i b i l i t y i s that the in d iv id u a ls taken in deep water at night were the r e s u lt o f contamination from shallower waters as the net was being lowered and ra ise d . This contamination may be part o f the explanation but a s u f f ic ie n t number of specimens were recovered from th ese deep n ight hauls to suggest that there were a c tu a lly some in d iv id u a ls present at the fis h in g depths. A th ir d , and most probable, fa cto r explain in g the presence o f S tr e e ts ia pronoides in the deep, nighttim e samples i s th at many m igrating organisms undergo a descent during the dark hours o f the n ig h t. This n ig h t tim e descent may represent a search for an optimum lig h t in te n s ity during a tim e when lig h t i s absent^frora the Figure 3 6. —Day and night depth d is tr ib u tio n o f S tr e e ts ia § ronoides based on the percentages o f p o s itiv e samples, ar width of one inch equals 100 per cent p o s itiv e samples. 151 PLATE XIX S. pronoides looo- day night 36 153 environment. Thus there i s a spreading out o f the population v e r t ic a lly follow ed by a r i s e at or before dawn. S. pronoides may engage in a nighttim e descent as described above. Phronima sedentaria During the d ayligh t hours Phronima sedentaria was c o lle c te d in samples ranging in depth from about 275 to 1000 m eters. The g r e a te st concentration o f in d iv id u a ls at t h is time was in a depth range o f from 200 to 400 m eters. There was a d is t in c t r is e o f in d iv id u a ls towards the sur face a t n ig h t. P la te XX, Figure 37, ill u s t r a t e s the day and night depth d is tr ib u tio n s fo r Phronima se d e n ta r ia . As was suggested fo r S tr e e ts ia pronoides i t i s suspected th at P. sedentaria engages in a nighttim e descent accounting for the wide range o f capture depths during the dark hours. Hyperia galba P late XXI, Figure 3ft, shows the day and night depth d istr ib u tio n s for Hyperia galb a. In d iv id u a ls o f th is sp e c ie s were taken a t depths ranging from about two hundred to one thousand meters during the day and from about f i f t y to s ix hundred m eters at n ig h t. The population appeared to be rather evenly d istrib u ted during the daytime. The absence o f p o s itiv e samples between s ix hundred and seven Figure 3 7 .—Day and n ight depth d is tr ib u tio n o f Phronima sedentaria based on the percentages o f p o s itiv e samples. Bar width o f one inch equals 100 per cent p o s itiv e samples. 154 PLATE XX E . sedentaria night 37 Figure 3#»—Day and n ig h t depth d istr ib u tio n o f Hyperia galba based on the percentages o f p o s it iv e samples. Bar width o f one inch equals 100 per cent p o s itiv e samples. 156 PLATE XXI H. a alba o- 200 - 4 0 0 - Dm 600 - 800- 1000- day night 38 158 hundred meters i s probably a r e s u lt o f in s u ff ic ie n t sampling in th a t depth range. This sp ec ies apparently engages in a mass movement o f the e n tir e population towards the surface at n ig h t, concentrating at depths o f le s s than four hundred m eters. Some o f the population may undergo a nighttim e descent down to a depth o f s ix hundred m eters as in d icated by a few p o s itiv e samples. V ib ilia armata P late XXII, Figure 39, shows the day and n ight depth d is tr ib u tio n s for V ib ilia armata. This sp ec ies occurred in a very wide band extending from two hundred to eleven hundred meters during the day and from ten to eigh t hundred meters at n ig h t. As illu s t r a t e d in Figure 39, i t appeared th at the e n tir e population moved upwards about two hundred meters at n ight with l i t t l e concentration at or near the surface. The great abundance o f t h is sp e c ie s may have re su lte d in some contamination o f many o f the deep hauls but c e r ta in ly the upper lim it s o f the depth ranges are accurate. V ib ilia v ia t r ix This sp ec ies displayed a unique pattern o f v e r tic a l m igration. P la te XXIII, Figure 40, i l l u s t r a t e s th a t the daytime depth d istr ib u tio n was from ten to eleven hundred meters w hile at night V. v ia t r ix was c o lle c te d at depths Figure 3 9 .—Day and night depth d istr ib u tio n o f V ib ilia armata based on the percentages o f p o s itiv e samples. Bar width o f one inch equals 100 per cent p o s itiv e samples. 159 PLA TE XXII V . arm ata 200 - 400 - Dm 600 - 800 - 1000- day night 39 Figure 4 0 .—Day and night depth d istr ib u tio n o f V ib ilia v ia t r ix based on the percentages o f p o s itiv e samples. Bar width of one inch equals 100 per cent p o s itiv e samples. 161 PLATE XXIII V . viatrix o- 200 - 400 - Dm 600 - soo- iooo- day night 4 0 163 ranging from ten to eigh t hundred m eters. The s in g le record below nine hundred meters at night was probably a r e s u lt of contamination from shallow er depths. Apparently the d eep er -liv in g members o f the population r is e at n ig h t, r e s u ltin g in an absence o f in d iv id u a ls from great depths during the dark hours. This absence from very deep water at night i s probably v a lid sin ce V. v ia t r ix was a very common sp ecies and most c e r ta in ly would have been captured in deep samples had in d iv id u a ls been present. Eupronoe minuta This was the only other sp e c ie s b esid es V ib ilia v ia t r ix which was common at depths o f l e s s than one hundred m eters during the daytime. P late XXIV, Figure 41, i l l u s tr a t e s the day and night depth d is tr ib u tio n s fo r t h i s sp e c ie s. During the d aylight hours E. minuta was taken a t depths ranging from f i f t y to one thousand m eters. No in d iv id u a ls , however, were captured between four hundred and f iv e hundred m eters. A t o t a l o f f iv e samples were taken w ith in t h is depth range during the daytime so t h is apparent absence i s probably v a lid . The g r e a te st abundance o f E. minuta during the day was in the upper two hundred meters o f water. The nighttim e depth d istr ib u tio n shows an obvious massing o f in d iv id u a ls near th e surface in the upper two hundred meters o f water. There were, however, high percentages o f p o s itiv e s ta tio n s at th e three hundred Figure 4 1 .—Day and night depth d istr ib u tio n o f Eupronoe minuta based on the percentages o f p o s itiv e samples. Bar width o f one inch equals 100 per cent p o s itiv e samples. 164 PL ATE XXIV E. minuta 200 - 400 - Dm 600 - 800 - 1000- day night 41 166 to four hundred and s ix hundred to seven hundred meter l e v e ls . These deep, p o s it iv e , nighttim e samples may be the r e s u lt o f contamination from shallower depths or the occur rence o f a nighttim e descent during the dark hours. A nalysis o f consecutive samples I t i s the opinion o f t h is author that a more v a lid p ictu re o f m igratory a c t iv it y can be shown by d escribing the sp ec ies composition o f two or three con secu tive traw ls taken at appropriate tim es and depths to il l u s t r a t e v e r t ic a l movement. As complete sta tio n data are given in the appendices only depths and day or night inform ation are repeated here along with the sta tio n numbers. Only the more abundant sp ec ies are considered in t h is d iscu ssion ; for l e s s common ones the reader i s referred to the in d iv id u a l sp ecies accounts. S eries 1 S ta tio n 3291, day, 562 meters S ta tio n 3292, d usk-night, 170 m eters S ta tio n 3293, n ig h t, 35 meters S ta tio n 3294, day, 954 meters The above s e r ie s o f sta tio n s i s in the path o f the b asic pattern o f m igration th at i s suspected for many o f the common h yp eriid s. On the b a sis o f p in t a liq u o ts and shipboard observations the fo llo w in g sp ecies were noted as common in a l l four samples: 167 Eupronoe minuta Hyperia b engalensis Hyperia galba Paraphronima crasalp es Paraphronlma g r a c ilu s Phronima sedentaria V ib llia armata V ib ilia v ia t r ix The presence o f th ese sp ec ies in a l l four samples supports the suggested m igratory and v e r t ic a l d istr ib u t io n a l h a b its presented in the sp ecies accounts. With the exception o f V ib ilia v i a t r i x . whose wide depth range extends from the surface to at le a s t eig h t hundred meters * ■ during the day and n ig h t, the above l i s t o f sp ecies con s i s t s o f m igrating forms. S tation S eries 1 a lso i l l u s t r a t e s the r e s t r ic t io n o f certa in gammarid sp ec ies to deep water during a l l tim es of the day and n ig h t. The follow in g sp ec ies were captured only at the 954-meter sta tio n (6295): Cyphocaris rich ard i Eurvthenes obesus Orchomenella spp. Paracallisom a coecus Rhachotropis natator A s in g le Orchomenella and a few specimens o f Cyphocaris rich ard i were c o lle c te d in the 562-meter sample (6291). S e r ie s 2 S ta tio n 6346, day, 960 meters S ta tio n 6350, day, 3#5 meters These two sta tio n s were occupied on con secu tive days during the same time period with a depth d iffer en ce o f 168 about s ix hundred m eters. The fo llow in g sp ec ies occurred in both samples with approximately the same frequency: Cyphocaris anonyx Hyperia galba Paraphronima g r a c ilu s Those sp ecies which were taken from both samples but which were more abundant in the shallow traw l were: Paraphronima c r a ssip e s Phronima sedentaria V ib ilia armata The higher numbers o f th ese th ree sp ec ies in the shallower sample suggest a concentration o f th ese forms near the upper lim it o f th e ir daytime depth range. Those sp ecies which were c o lle c te d in only one o f the samples were: 385 meters 980 meters S tr e e ts ia pronoides Cyphocaris rich ard i V ib ilia v ia t r ix Eurythenes obesus Orchomenella spp. Paracallisom a coecus Rhachotropis natator The absence o f gammarids from the shallow er sta tio n again p o in ts out th e ir r e s tr ic tio n to deeper waters. S e ries 3 S tation 8427, day, 520 meters S tation 8428, dusk-night, 170 meters These two s ta tio n s ill u s t r a t e the m igration and concentration o f se v era l sp ecies o f amphipods towards the 169 surface at dusk. The follow in g sp ec ies were abundant in both samples: Hyperia galba Paraphronima cr a ssip es Paraphronima g r a c ilu s phronima sedentaria Primno macropa Scina b o r e a lis V ib ilia armata The massing o f in d iv id u a ls in the surface waters a t night i s illu s t r a t e d by the fa c t that although both traw ls were conducted for the same length o f tim e, the number o f specimens taken from the deep, daytime sample was 103 w hile the number from the shallow er, night sample was 391. These fig u r e s suggest that during the day the amphipod population i s more evenly d istrib u ted throughout i t s depth range than during the night when the in d iv id u a ls concentrate in the surface w aters. S e ries 4 S ta tio n #716, n ig h t, 425 meters S ta tio n 6717, n ig h t, 60 meters Both of these samples were taken in complete darkness on the same n ig h t. Those sp e c ie s which were taken in both samples are lis t e d below with the number o f each recovered from pint a liq u o ts. 425 m 60 m Paraphronima cr a ssip es 1 11 Paraphronima g ra c ilu s 1 9 Primno macropa 1 5 170 I t i s evident th at there was a massing o f the populations in shallow water during the n igh t. The sin g le specimens from the deeper sta tio n may represent contamina tio n from shallow water or may in d ic a te a nighttim e descent o f part o f the population. S e r ie s 5 S tation 9165, n ig h t, 400 m eters S tation 9166, n ig h t, 600 m eters S tation 9167, n ig h t, 200 meters The only amphipods noted in sta tio n 9165 during a q u a lita tiv e examination were one each of V ib ilia armata and V. v i a t r i x . Most of the m igrating forms were appar e n tly above t h is 400 meter depth during the n ig h t. S tation 9166 at 600 m eters produced se v era l specimens o f Cyphocaris r ic h a r d i. a d e e p -liv in g gammarid, and no in d iv id u a ls o f any o f the suggested m igrating forms. The follow in g sp ec ies were taken from sta tio n 9167 at a depth o f 200 m eters: Phronima sedentaria Primno macropa S tr e e ts ia pronoides V ib ilia armata A ll o f th ese sp ecies are considered to be m igrating forms. S e ries 6 S ta tio n 9053, n ig h t, 10 meters S ta tio n 9054, n ig h t, 50 meters S ta tio n 9055, n ig h t, 150 meters At the time these s ta tio n s were occupied, a strong therm ocline was present at about th ir ty to f i f t y m eters. 171 The f i r s t two s ta tio n s (ten and f i f t y m eters) produced the same th ree sp ecies: V ib ilia armata V ib ilia v ia t r ix S tr e e ts ia pronoides (one specimen in each sample) V ib ilia v ia t r ix was the most abundant sp ecies in the ten meter sample but was g rea tly outnumbered by V. armata a t f i f t y m eters. These two sp ec ies o f V ib ilia do r is e to or near the surface at n igh t. The one hundred f i f t y meter sample picked up some of the other m igrating sp ec ies which do not r is e so clo se to the surface: Phronima sedentaria Primno macropa These two sp e c ie s, among oth ers, are unable to penetrate the therm ocline as they migrate upwards at n igh t. S e r ie s 7 S ta tio n 8956, n ig h t, 15 meters S tation 8957, n ig h t, 50 meters S tation 8958, n ig h t, 285 meters S tation 8959, morning, 1000 m eters The f i r s t sample of S e r ie s 7 y ield ed only a few in d iv id u a ls o f V ib ilia v ia t r ix in d ic a tin g , again, that t h is i s one of the few sp ecies which i s capable o f crossin g the therm ocline. The f i f t y meter sample produced both V ib ilia v ia t r ix and V. armata. The th ird night sample (285 meters) obtained many of the common m igrating sp ecies: 172 Hyperia galba Paraphronima cr a ssip es Paraphronima g r a c ilu s Phronima sedentaria S tr e e ts ia pronoides V ib ilia armata V ib ilia v ia t r ix The fourth sta tio n at one thousand meters taken early in the day contained many o f the d e e p -liv in g gammarids and a few specimens of Hyperia ga lb a . I t i s questionable whether H. galba had a c tu a lly reached a depth o f one thousand meters by morning or that th e ir presence in the sample was a r e s u lt o f contamination from shallower depths. S eries 8 S tation 8961, day, 540 meters S tation 8964, n ig h t, 1000 meters The above two s ta tio n s were conducted with the su c c e ssfu l operation o f the Foxton c lo sin g d evice. A comparison was made o f the samples from fish in g depth with the samples taken as the net was being lowered and raised from fish in g depth. The "at depth" sample from sta tio n 8961 revealed f iv e sp ec ies o f amphipods considered to be m igrating forms. Hyperia galba Paraphronima cra ssip es Paraphronima g ra c ilu s V ib ilia armata V ib ilia v ia t r ix 173 A very few in d iv id u a ls o f V ib ilia spp. and Paraphronima spp. were recovered from the ”up and down” catch. S tation #961 was conducted in the morning a fte r dawn and before noon. The above-mentioned sp ec ies had apparently reached the depth o f 450 meters by the early d ayligh t hours. Eupronoe minuta was abundant in the ”up and down” catch o f sta tio n $961. The presence o f t h is sp ecies in that catch supports evidence presented e a r lie r that E. minuta i s present at shallow depths during a l l times o f the day and n ig h t. No hyperiid m igrators were c o lle c te d in the "at depth” sample from sta tio n $964. Many gammarid sp ec ies, however, were p resen t. Cyphocaris rich ard i Orchomenella spp. Rhachotropis natator Paracallisom a coecus The ”up and down” catch from sta tio n $964 included four m igrating sp e c ie s. Hyperia galba Paraphronima cr a ssip es Paraphronima g r a c ilu s S tr e e ts ia pronoides Several specimens o f Eupronoe minuta were a lso taken in the ”up and down” catch o f sta tio n $ 964. The absence o f hyperiid m igrators from the one thousand meter sample i l l u s t r a t e s the movement of those 174 forms in to shallower water during the n ig h t. This sample was taken from about 0200 to 0400 hours, in t o t a l darkness. Apparently any nighttim e descent in which m igrating sp ecies p a r tic ip a te does not reach one thousand m eters. S eries 9 S tation 959#, day (morning), 100 meters S tation 9599, day, 50 meters S tation 9600, day, 20 meters S tation 9601, day, 100 meters This s e r ie s o f short traw ls was taken in order to determine which sp ecies of amphipods were at or near the surface during the daylight hours and to provide further evidence that the ty p ic a l m igrating forms were absent from shallow depths during the day. Only two sp ecies (Eupronoe minuta and V ib ilia v i a t r i x ) were recovered from a complete so rtin g of a l l four samples. E. minuta was very abundant in the two one hundred meter samples and p resen t, but in sm aller numbers, in the f i f t y meter s ta tio n . This sp ecies was not c o lle c te d in the twenty meter sample. As has been shown e a r lie r , E. minuta i s common at shallow depths during the day and n igh t. Only the d eep er -liv in g in d iv id u a ls move upwards at night at which time the g re a te st concentrations o f the population occur in shallow water. This sp ecies i s unable to pene tr a te the therm ocline and i s r e s tr ic te d to depths o f f i f t y meters or g reater. 175 V ib ilia v ia t r ix was present in three o f the four samples, being absent from one o f the one hundred meter tra w ls. This s p e c ie s , as w e ll as Eupronoe minuta, was common at shallow depths during both day and n igh t hours. V. v i a t r i x , however, was able to penetrate the therm ocline. From the preceding sectio n of the d iscu ssio n i t can be seen th a t there were sev era l p attern s of v e r tic a l zona- tio n and m igration among the lo c a l mid-water amphipods. Although there appears to be a general movement of mid water organisms towards the surface at night and to deeper waters during the day, one can see th at there are some rather in tr ic a t e p attern s w ithin t h is b asic migratory path. I t should be pointed out that the samples discu ssed above are only a few examples o f many s e r ie s o f sta tio n s which illu s t r a t e d the suggested p atterns of v e r t ic a l movement and d istr ib u tio n . The fa cto rs which in flu en ce the migration o f amphipods, as with other m igrating organisms, are d i f f i c u l t to d efin e . Certain c o r re la tio n s can be seen between lig h t in te n s ity and v e r t ic a l movement but th e se are only sugges t iv e ; the a ctu al in flu e n c e of lig h t on the a c t i v i t i e s o f amphipods i s sp e c u la tiv e . The barrier presented by the th e m o c lin e for most m igrating sp ecies suggests that temperature i s a lso an important fa c to r . The true e f f e c t s of temperature change on m igrating organisms, however, i s unknown. 176 Some o f the advantages to moving in to shallow water at night and r e tr e a tin g to deep water during the day have been mentioned e a r lie r . Such th in gs as nighttim e feeding on shallow water plankton and the concealment in deep waters during the daytime are probable advantages. In addition to th e se , v e r t ic a l movement may be an aid in geographical d is tr ib u tio n . This i s e s p e c ia lly probable in those sp e c ie s which m igrate great d ista n c es or which have ex ten siv e v e r t ic a l ranges. By moving in to and out o f d iffe r e n t currents in d iv id u a ls may be h o r iz o n ta lly d is persed. Raymont (1963) su ggests an evolutionary s i g n i f i cance to v e r t ic a l m igration s. By the overlapping and v e r tic a l m ixing o f organisms a more ex ten siv e gene exchange i s made p o s s ib le . C ertainly th ese la t te r su ggestion s are areas which are r e la t iv e ly unexplored and would provide extremely in te r e s tin g f i e l d s for research. Reproductive A c tiv ity The reader i s again referred to the in d iv id u a l sp ec ies accounts for complete data on the breeding cycle of each araphipod sp ec ies. Certain gen eral trends were apparent in the reproductive a c t i v i t i e s o f the amphipod fauna. P la te XXV, Figure 42, i l l u s t r a t e s the percentages o f mature fem ales of the t o t a l amphipod population which were carrying ova Figure 4 2 .—V ariation in the percentages o f the t o t a l female amphipod population carrying ova and young through out the year. 0 - ova Y - young 177 PLATE XXV 50 40H 30H lO-i w F W 42 179 or young throughout the year. I t can be seen that the peak o f ova production occurred during the la te summer and f a l l months. P late XXVI, Figure 43, shows the number o f sp ec ies which had th e ir maximum percentages o f fem ales with ova and young during d iffe r e n t seasons. The highest number of sp ecies carrying ova was noted in the f a l l and the h igh est number carrying young occurred in the spring. The follow ing l i s t s co n sist of the most abundant species of amphipods captured and show t h e i r seasons of reproductive a c t i v i t y . Species with t h e i r h ig h e st percentages of ovigerous fem ales in the summer: Cyphocaris anonyx Eupronoe minuta Hyperia galba Phronima sedentaria Primno macropa Species with the h ig h est percentages of ovigerous females in the f a l l : Cyphocaris rich ard i Hyperia b engalensis Paraphronima cra ssip es Paraphronima g r a c ilu s P la ty sc e lu s serratu lu s Primno macropa S tr e e ts ia pronoides V ib ilia v ia t r ix None of the common species of amphipods displayed high ova production in th e w inter or spring. Figure 4 3 .--S eason al record o f the number o f sp ecies showing h ighest percentages o f fem ales with ova and young. 0 - ova Y - young 180 PLATE XXVI 10- spp. W F 43 182 S pecies with the h ig h e st percentages of fem ales carrying young in the w inter: Cyphocaris richardi V ib ilia v ia t r ix Species with the h igh est percentages o f fem ales carrying young in the spring: Eupronoe minuta Hyperia galba Paraphronima cra ssip es Primno macropa S tr e e ts ia pronoides V ib ilia armata Species with the h igh est percentages o f fem ales carrying young in the summer: Eupronoe minuta ( same per cent as spring) Paraphronima g r a c ilu s Species with the h igh est percentage o f fem ales carrying young in the f a l l : Hyperia b en galen sis These above l i s t s serve to o ffe r more evidence for the suggested breeding times for the general amphipod population. In most sp ecies the young were relea sed from the brood pouches in the la t e spring and ea rly summer. Bigelow (1926) a lso reported th at the la t e spring and early summer were the reproductive periods for most hyperiid amphipods. E arlier in the d iscu ssio n th ere was shown the seasonal v a ria tio n in the numbers per traw l hour o f the t o t a l amphipod population (Plate XVII, Figure 34, page 125)- I llu s tr a te d in th at fig u re i s a great r is e in the abun dance o f amphipods during September, October, and November. This r is e apparently represents the time at which the young amphipods enter the ,T catch ab le,f population. The lag period o f about three months i s d i f f i c u l t to exp lain . Bigelow (1926) suggested that young amphipods were very common in the upper tw en ty -fiv e meters o f water but t h is su ggestion was not supported by any data c o lle c te d during t h i s present study. Since a great number o f very small organisms were captured by the IK M W T i t i s t h is authorfs opinion that i f the young amphipods were abundant in the surface waters th e ir presence would have been detected during shallow sampling. The whereabouts o f the ju v e n iles a fte r r e le a se from the brood pouches and before they are captured with the adult population i s unknown. Their entrance in to the ’’catch ab le” population resu lted in an in crease in popula tio n d en sity , as sta ted above, and, for many sp e c ie s, a drop in mean s iz e and an extension o f the lower lim it o f the s iz e range. I t can be seen that the p r e c ise a n a ly sis o f the reproductive c y c le s o f in d iv id u a l sp ecies and o f the amphipod population in general are extremely complex. The fa c t th at the amphipods brood the young makes the group an id e a l one for em bryological s tu d ie s . The development and 184 ecology of the young amphipods could provide e x c e lle n t m a te ria ls for fu tu re research. O rien ta tio n and Swimming A few shipboard observations were made on the s p a tia l o rie n ta tio n and swimming behavior of th e amphipod species which were commonly taken a liv e in th e samples. The follow ing species were c o n s is te n tly recovered from th e traw l in an a c tiv e condition: Hyperiidea Gammaridea Eupronoe minuta Eurythenes obesus Hyperia galba Paraphronima c ra ssip e s Paraphronima g ra c ilu s Phronima se d en ta ria Primno macropa S t r e e t s i a pronoides V ib ilia armata V ib ilia v i a t r i x Eupronoe minuta Specimens of t h i s species were often found f lo a tin g on the surface of the water a f t e r being placed in s o rtin g pans. These in d iv id u a ls appeared to be p a r t i a l l y trapped by the surface film o f the w ater. Those in d iv id u a ls which were not trapped a t the surface were noted to swim on t h e i r sid e s, s p ira lin g very ra p id ly as they swam up or down through the water. 185 The head of t h i s species is somewhat l a t e r a l l y compressed and th e eyes are d ire c te d l a t e r a l l y from the sid e s of th e head. The above described o rie n ta tio n would f a c i l i t a t e the d ire c tio n of the ommatidia towards the l i g h t ; t h a t is , v e r t i c a l l y r a th e r than h o riz o n ta lly . Hyperia galba This species was noted to be a very strong swimmer although i t was not observed to m aintain any p a r tic u la r o r ie n ta tio n . The eyes occupy n e a rly th e e n tir e s id e s , f r o n t , and dorsum of th e head and H. galba may, th e re fo re , p erceiv e li g h t re g a rd le s s of i t s o rie n ta tio n to the lig h t source. Paraphronima spp. The two species o f Paraphronima were ty p ic a lly noted to swim randomly through containers o f water with t h e i r v e n tra l su rfaces d ire c te d upwards. Since the ommatidial f a c e ts are located on th e v e n tra l surface of the head, t h i s o r ie n ta tio n would f a c i l i t a t e perception of lig h t coming from the surface o f the w ater. Both species were observed to be rap id and very strong swimmers. Phronima se d e n ta ria On th re e occasions th e swimming behavior of t h i s species was observed while the in d iv id u a ls were in sid e 186 t h e i r salp " b a r r e l s . ” These specimens were noted to extend t h e i r abdomens out of the " b a r r e l” and clin g to th e in sid e of the salp with the ch elate gnathopods. In t h i s p o s itio n they swam in a s p ir a lin g fashion by beating the pleopods. Low speeds and sporadic movements ty p if ie d t h i s a c t i v i t y . They never swam for more than a few seconds w ithout r e l a x ing, a t which time they began to sink. O verall progress, th e re fo re , was s li g h t. As was discussed e a r l i e r , t h i s species does m igrate towards the surface a t n ig h t. This v e r t i c a l movement involves a minimum upwards m igration of two hundred f i f t y m eters fo r a t le a s t some of the popula tio n . In the lig h t o f the observed swimming a c t i v i t y , i t i s s u rp ris in g th a t t h i s extensive v e r t i c a l movement i s su c c essfu lly accomplished. Primno macropa No p a r tic u la r o r ie n ta tio n was observed fo r members of t h i s sp e c ie s. They appeared to be r a th e r ra p id swimmers d a rtin g about in the water w ith no s p e c ific p o sitio n in g to the su rface. S tr e e ts ia pronoides This species was observed to be r a th e r a weak and slow swimming form. I t was, however, recorded as m igrating v e r t i c a l d istan c e s of a t le a s t two hundred f i f t y meters during the n ig h t. As was s ta te d fo r Phronima s e d e n ta r ia . 187 t h i s v e r t i c a l movement i s su rp risin g in view of the observed swimming behavior, V ib ilia spp. These two species were ty p ic a lly recovered in e x c e lle n t condition. They were observed to swim very ra p id ly , d a rtin g in a l l d ir e c tio n s with no p a r tic u la r o r ie n ta tio n to th e surface. Eurythenes obesus Although t h i s species was r a re in the lo c a l samples, i t was always a liv e when c o lle c te d and was the only gammarid species commonly taken a liv e . I t did not appear to swim a t a l l but was noted simply to move i t s peraeopods and pleopods e i t h e r f lo a tin g on the surface or r e s tin g on the bottom. I f , as was suggested e a r l i e r , t h i s species is demersal and does move v e r t i c a l l y through the w ater, the mechanism o f such a movement i s not apparent. D irect observations provide no explanation, but two p o s s i b i l i t i e s are here suggested. I f the v e r t i c a l movement i s not d iu rn a l the amphipods may a c tu a lly "swim" up and down in the water over extended periods of time. I f the movement i s rap id and asso c ia ted with p erio d s of feeding, th e re may be some mechanism or mechanisms f o r f lo a tin g up to s h a l lower depths and then sinking back towards the bottom through a bouyancy adjustm ent. I t can be seen th a t in some cases th e re are b eh a v io ral and m orphological a d a p tatio n s to a m igratory a c t i v i t y . In general i t can be said th a t those species which do engage in v e r t i c a l m igrations o ften possess large and w ell-developed eyes while those r e s t r i c t e d to g r e a te r depths which do not move v e r t i c a l l y or move only w ithin the deep la y ers of the w ater possess very small and weakly developed eyes. Ecological R elatio n sh ip s I t should be pointed out at t h i s time th a t th e re e x is t some re la tio n s h ip s among amphipods and between amphipods and c e rta in o th er organisms found in the study area. From the sometimes r a d ic a l v a r ia tio n s in abundance of c e rta in species i t i s suggested th a t some amphipods are g regarious. In forms such as V ib ilia spp. and Paraphronima sp p . i t was noted th a t some samples contained huge numbers of in d iv id u a ls while sim ila r tra w ls on the same day pro duced normal q u a n titie s . This v a r ia tio n in abundance was e s p e c ia lly n o tic a b le during the n ig h t when the m igrating species were concentrated near the surface. The use of empty salp t e s t s by Phronima sed en taria has already been mentioned and i s recorded in much o f the e a r l i e r l i t e r a t u r e . 189 The commonest a sso c ia tio n noted during t h is study was between in d iv id u a ls of V ib ilia v ia t r ix and various sp ecies of sa lp s. Very long chains o f salp zooids floatin gs on or near the surface often contained liv in g specimens o f V. v i a t r i x . Other p e la g ic tu n ic a te s such as Pyrosoma a lso often contained in d iv id u a ls o f th is common amphipod species. I t has been reported in e a r lie r lite r a tu r e that Hyperia galba i s often found a sso c ia ted with medusae such as A urelia and Cvanea. Such an a sso c ia tio n was noted on one occasion during t h i s present study but the host was damaged beyond id e n tific a tio n . Barnard, K. H. (1932), mentioned that Cystisoma pellucidum at times contained many copepods scattered throughout the body c a v ity . This r e la tio n sh ip was observed in two in stan ces during th is present study. I d e n tific a tio n o f Local Mid-water Amphipoda Presented in t h i s se ctio n are notes on the id e n tific a tio n and sex determ ination o f the amphipods c o lle c te d during t h is study. In certa in in sta n ces r e fe r ences are offered which provide more d e ta ile d accounts of some o f the lo c a l amphipod groups. The two suborders o f mid-water amphipods can be u su ally separated on the b a sis o f the fo llow in g character i s t i c s : 190 Suborder Hyperiidea: Head and eyes ty p ic a lly la rg e, m axillary palps absent, coxal p la te s o f the th oracic le g s often small or fused with the body. Suborder Gammaridea: Head and eyes sm all, m axillary palps p resen t, thoracic le g s with w ell-d eveloped coxal p la te s . Suborder Gammaridea Family Eusiridae Rhachotropis n a ta to r .— characterized by an extremely fr a g ile body; p o ssesses very large gnathopods; t h i s sp ecies i s often damaged in c o lle c tin g and i s u su a lly found flo a tin g on the surface o f the water w hile so rtin g . Family Lysianassidae Cyphocaris ri_chardi.--commonly red in l i f e , turning pale yellow to white a fte r preservation;rostrum extending w ell beyond the head and term inating in a p o in t. Cyphocaris anonyx. —red in l i f e ; sm aller than r ic h a r d i; rostrum short and term inating in a blunt end. Eurythenes ob esu s. —large robust body; grey to white in l i f e ; peraeopods with long, curved d actylu s. Paracallisom a coecu s. — large robust body; red to orange in l i f e , turning white a fte r p reservation; males are d istin g u ish ed by the presence o f elongate second antennae, t y p ic a lly about three tim es as long as in the fem ales. Suborder Hyperiidea Family Hyperiidae (males p o ssess a very long and m u lti- a r tic u la te pair o f f i r s t antennae) Hyperia b en g a len sis. —ty p ic a lly dark red in l i f e ; sm all, le s s than 5 m m in length; characterized by 191 the presence o f a pair o f trian gu lar spines on the v en tra l sid e o f the head. Hyperia galba and Hyperia sp in ig er a . —these two sp ecies are d i f f i c u l t to d istin g u ish in the f ie ld . Both are la r g e, red, robust h yperiids; Barnard, K. H. (1932), separates the two sp ecies whereas Shoemaker (1945) considers them very sim ila r i f not id e n tic a l. Family P la ty sc e lid a e (females lack second antennae) P la ty sc e lu s se r r a tu lu s. —body small; head much broader than deep, f i f t h peraeopods reduced. Family Phrosinidae (males lack second antennae) Primno macropa. —p ossess purple to red pigmentation spots on an otherw ise w h itish body; head ir r e g u la r ly globose; w ell-developed second gnathopods ( su b c h e la te ). Family Pronoidea (males lack second antennae) Eupronoe m inuta. —ty p ic a lly reddish with la r g e, tria n g u la r, purple eyes; head smooth and la t e r a lly compressed. Family Cystisomidae (Barnard, K. H. D-932J, o ffe r s a key to the sp e c ie s) Cystisoma f a b r i c i i . —very large (22 to 103 mm), transparent; 2 p airs of v en tra l spines on the head; antennae a r is e very c lo se togeth er. Cystisoma pellucidum . —very large (64 to 116 mm), transparent; 5 to 7 p airs o f v en tra l spines on the head; antennae a r ise far apart. Family Oxycephalidae (fem ales lack second antennae) Qxycephalus c l a u s i. —proximal portion o f head bulbous, d i s t a l portion trian gu lar; d orsal surface of body carinate with depressions between segments of pereon. Calamorhynchus r ig id u s . —oblong eyes; head fla tte n e d d o r so v e n tr a lly ; head tw ice as wide as long. 192 S tr e e ts ia pronoides. —head very elongate and s lig h t ly compressed la te r a lly ; very long, pointed rostrum. Family Phronimidae Phronima se d e n ta ria . —head la rg e, deeper than body; d orsal portion o f head produced in two d o rso la ter a l bulbs, taperin g v e n tr a lly ; body transparent; males p ossess short, blunt f i r s t antennae; females have much narrower pleopods than the m ales. Family Paraphronimidae (fem ales p o ssess much narrower pleopods than the males) Paraphronima c r a s s ip e s . — sim ilar to Phronima but t y p ic a lly sm aller; head s lig h t ly compressed la t e r a l l y and rounded, not tapered as in Phronima; peraeopods 3-7 lack sp in es. Paraphronima g r a c ilu s . —as P. cr a ssip es but with numerous sp ines on peraeopods 3-7. Family V ib iliid a e V ib ilia armata. —head small; eyes gam marid-like; orange to red in l i f e ; f i r s t antennae la n ce o la te . V ib ilia v i a t r i x . —as above but u su a lly larger with dark reniform eyes; f i r s t antennae b lun t. Family Scinidae (head and eyes sm all, gammarid-like; f i r s t antennae styliform Qlurley, 1956, p resen ts a key to the sp ec ies^ .) CHAPTER IV SU M M A RY This study o f the mid-water amphipods o f f the coast of southern C aliforn ia involved nineteen sp ec ies o f the Suborder Hyperiidea and s ix sp ec ies o f the Suborder Gammaridea, a t o t a l o f tw en ty -fiv e sp e c ie s. Two sp ecies of the Family Oxycephalidae (Qxycephalus c la u s i and Calamorhynchus rig'idus) not p reviously reported from C alifornian waters were taken during t h is study, r a isin g the known number of lo c a l p ela g ic hyperiid s from fo r ty - three to f o r t y - f iv e . The fo llo w in g i s an a lp h a b e tic a l l i s t o f the fa m ilie s represented by specimens c o lle c te d during the study, together with the number o f sp ecies representing each fam ily. Suborder Gammaridea E u sirid ae , 1 sp. L ysianassidae, 5 spp. Suborder Hyperiidea Cystisom idae, 2 spp. H yperiidae, 3 spp. Oxycephal'idae, 3 spp. Paraphronimidae, 2 spp. Phronimidae, 1 sp. Phrosinidae, 1 sp. P la ty s c e lid a e , 1 sp. 193 194 Pronoidea, 1 sp. Scinidae, 3 spp. V ib iliid a e , 2 spp. Conclusions V e r tic a l d istr ib u tio n and m igration An attempt was made to understand the patterns of v e r tic a l d istr ib u tio n and m igration of the various amphi pods. With the exception o f Cyphocaris anonyx a l l o f the gaxnmarid sp ec ies were found to be d eep -liv in g forms common only in samples from depths o f seven hundred meters jor greater. There appears to be a diurnal movement in at le a s t some o f the gammarid sp ec ies (Rhachotropis n a ta to r ) in volvin g a r is e to shallower depths during the day and a sinking at n ig h t. Due to a lack o f s u f f ic ie n t data, how ever, no g e n e r a liz a tio n s can be made regarding the v e r t ic a l movements o f the gammarids. The hyperiid sp ecies are nearly a l l migratory types. The in d ivid u al v e r t ic a l d is tr ib u tio n a l and migratory p at tern s are given in the sp ecies accounts and in the d isc u s sio n . There appears to be sev era l d is t in c t p atterns o f v e r t ic a l movement. With the exception o f a few sp ecies th e upper depth lim it o f the h yperiid s was defined by the therm ocline. Most o f the sp ec ies were never captured above f i f t y meters during any time o f the year, even when the therm ocline was 195 very weak. From repeated sampling and a n a ly sis o f abundance i t i s suggested that most o f the h yperiid s e x is t in a thick band down to depths o f greater than one thousand meters during the daytime. The hyperiid sp ec ies were most h eavily concentrated between about two hundred and s ix hundred meters during the d a yligh t hours. Most o f th ese forms r is e to shallower depths during n ig h tly m igrations towards the su rface. The most in flu e n t ia l fa c to r s e f f e c t ing these m igrations appear to be lig h t and temperature. Reproductive a c t iv it y The information regarding the reproductive a c t iv it y o f the lo c a l amphipods has led to the several con clusion s. Data on each sp ecies are given in the in d iv id u a l sp ec ies accounts and in the d isc u ssio n . The fo llo w in g g e n e r a liz a tio n s can be made p ertain in g to reproductive a c t iv it y of lo c a l amphipods: 1. Ova production was h ig h est for most sp ec ies in the f a l l months. 2. The h ig h est incidence o f fem ales carrying young in the brood pouches was in the la te spring and ea rly summer. 3. Young were apparently relea sed from the brood pouches by ea rly summer. 4. There was a s ig n if ic a n t r is e in the d en sity of the t o t a l amphipod population in the f a l l . This r is e in d ic a te s the entrance o f the young in to the mature population and was accompanied by drops in mean s iz e s and in the lower lim its o f the siz e ranges. 196 Comparison o f study areas By studying several s e le c te d samples from the San Pedro Channel and comparing them with the samples from the Outer Santa Barbara Passage i t was apparent that the faunal composition of the two areas was sim ila r . I t appeared that there was no elim in ation of d eep -liv in g forms in the shallow er region but rather that the v e r t ic a l ranges were simply narrower than in the deep area. Research op portu nities A great d eal o f work remains to be done on mid-water organisms. C ertainly with a more refin ed technique o f sampling the ecology of various forms w ill become much clea rer. The use o f c lo sin g d evices w i l l enable the worker to e s ta b lish accurate depth d is tr ib u tio n s and o ffe r p recise inform ation on the h a b its of v e r t ic a l m igration. An in ten se study o f the seasonal v a ria tio n in faunal con d ition s should provide d eta iled data concerning the reproductive cy cles which are thus far unknown or sp ecu la tiv e for many organisms. APPENDICES Appendix I S tation Data fo r Outer Santa Barbara Passage S ta. No. Date S tart P o sitio n Depth Time F inish P o sitio n Depth Time Depth Fished SOI 8 7-19-62 33-24-40 N 740 fth . 1227 33-12-15 N 740 f t h . 1715 900 m 11S - 52-20 W 11S - 2S-00 V / S02 4 S- 7-62 33-24-48 N 710 fth . 1227 33-19-lS N 705 fth . 1540 378 m l l S - 52-10 W 118- 41-42 W 8025 S- 7-62 33- 20-00 N 710 fth . 1624 33-13-38 N 685 f th . 2005 522 m 11S -44- 1S W 118-33-50 W S026 S- S-62 33-20-00 N 690 fth . 0704 33-24-24 N 720 f th . 1022 504 m 11S-3S-22 W 118-48-26 W S027 S- S-62 33-25-12 N 718 f t h . 1043 33-19-30 N 705 f t h . 1409 468 m 118-43-35 W 118-38-24 W S029 S- S-62 33-17-40 N 715 fth . 2003 33-11-09 N 680 fth . 2354 666 m 11S-40-00 W 118-29-35 W S030 S- 9-62 33-11-30 N 665 f t h . 001S 33-08-36 N 590 fth . 0345 540 m 11S-29-1S W 118-18-18 W S031 S- 9-62 33-OS-45 N 595 fth . 0436 33-12-41 N 680 fth . 0744 540 m 11S-17-2S W 118-39-50 W S i l l S-21-62 33-24-33 N 690 fth . 1217 33-18-18 N 695 f th . 1618 750 m llS -5 1 -5 0 W 118-39-50 W 8114 S-22-62 33-20-06 N 693 fth . 1525 33-10-09 N 655 f t h . 1910 650 m 11S-37-14 ¥ 118-25-26 W Appendix I— Continued Sta. No. JJate S tart P o sitio n Depth Time Finish P o sitio n Depth Time Depth Fished 6115 6-22-62 33-09-45 N 650 fth . 1940 33-15-45 N 715 fth . 2344 750 m 116-25-21 W 116-27-00 W 6116 6-23-62 33- 16-12 N 713 fth . 0019 33-22-35 N 714 f t h . 0325 400 m 116-36-20 W 116-50-26 W 6117 6- 23-62 33-22-47 N 714 fth . 0354 33-17-16 N 715 fth . 0741 65O m 116-51-00 W 116-40-00 W 6116 9 - 4-62 33-24-36 N 660 fth . 1224 33-17-04 N 695 fth . 1716 927 m 116-52-32 W 116-39-36 V / 6119 9 - 5-62 33-21-03 N 710 fth . 0710 33-24-27 N 720 fth . 0945 266 m 116-39-47 W 116-50-00 W 6120 9 - 5-62 33-24-25 N 716 fth . 1012 33-16-16 N 710 fth . 1502 945 m 116-49-32 W 116-32-46 W - ■ 6121 9- 5-62 33-15-42 N 710 fth . 1530 33-09-56 N 660 f th . 1614 360 m 116- 36-56 W 116-26-27 W 6122 9- 5-62 33-10-00 N 700 fth . 1635 33-17-16 N 705 fth . 2325 945 m 116-29-32 W 116-41-00 W 6123 9- 5-62 33-17-36 N 710 fth . 2353 33-13-26 N 690 f th . 0231 360 m 116-40-00 W 116-30-43 W 6236 10-25-62 33-26-26 N 690 fth . 0955 33-21-16 N 695 fth . 1513 975 m 116-52-35 W 116-45-25 W 6239 10-25-62 33-16-12 N 713 f th . 0019 33-22-35 N 714 fth . 0325 400 m 116-36-20 W 116-50-26 W Appendix I— Continued Sta. No. Date S tart P o sitio n Depth Time Finish P o sitio n Depth Time Deptl Fishe< 8240 10-25-62 33-08-24 N 650 fth . 1905 33-16-57 N 675 f t h . 2200 300 m 118-27-58 W 118-35-26 W 8242 10-26-62 33-15-45 N 700 fth . 0817 33-24-38 N 700 f t h . 1227 860 m 118-37-24 W 118-49-00 W 8243 10-26-62 33-24-00 N 695 fth . 1300 33-16-32 N 695 fth . 1613 600 m 118-50-10 W 118-40-00 W 8291 11- 8-62 33-27-30 N 650 fth . 1239 33-19-30 N 680 fth . 1622 562 m 118-53-40 W 118-41-02 W 8292 11- 8-62 33-19-15 N 685 fth . 1709 33-24-45 N 690 f t h . 1850 170 m 118-40-27 W 118-49-04 W 8293 11- 8-62 33-29-50 N 695 fth . 2015 33-24-18 N 470 fth . 2250 85 m 118-49-00 W 118-37-34 W 8295 11- 9-62 33-16-15 N 690 fth . 0809 33-25-10 N 695 fth . 1300 954 m 118-36-30 W 118-49-33 W 8296 11- 9-62 33-24-29 N 690 fth . 1336 33-17-27 N 690 f t h . 1624 500 m 118-51-00 W 118-40-30 W 8298 11- 9-62 33-11-53 N 690 fth . 180 5 33-22-18 N 610 fth . 2103 475 m 118-39-18 W 118-39-40 W 8346 12- 6-62 33-27-00 N 660 f t h . 1204 33-18-45 N 705 fth . 1657 980 m 118-55-15 W 118-40-27 W 8347 12- 6-62 33-18-58 N 695 fth . 1732 33-26-25 N 680 fth . 2040 e 0 to 118-39-40 W 118-49-51 W 200 Appendix I— Continued S ta. No. Date S ta r t P o sitio n Depth Time F in ish P o sitio n Depth Time Deptl Fishec 8349 12- 7-62 33-26-38 N 660 f t h . 0642 33-17-04 N 715 f th . 1137 900 m 118-54-15 W 118- 40-56 W 8350 12- 7-62 33-16-45 N 715 f th . 1208 33-09-44 N 665 f th . 1513 385 m 118- 40-30 W 118- 30-30 W 8427 1- 3-63 33-24-27 N 705 f th . 1224 33-17-15 N 675 f th . 1551 520 m 118- 50-08 W 118-38-45 W 8428 1- 3-63 33-17-32 N 695 f th . 1628 33-24-4 8 N 700 f th . 1915 170 m 118- 32-28 W 118- 46-32 W 8430 1- 4-63 33-12-37 N 710 f th . 0803 33-23-20 N 715 f th . 1334 800 m 118-35-20 W 118-49-00 W 8433 1- 4-63 33-18-44 N 675 f t h . 1900 33-26-58 N 455 f th . 2155 300 m 118-35-15 W 118-43-55 W 8506 3-28-63 33-22-00 N 720 f th . 1240 33-16-30 N 685 f th . 1340 300 m 118-46-12 W 118-36-08 W 8508 3-28-63 33-15-20 N 685 f th . 1705 33-18-51 N 690 f th . 1845 425 m 118-30-12 W 118-38-20 W 8509 3-29-63 33-17-45 N 700 f th . 0812 33-22-32 N 700 f t h . 1017 600 m 118-38-45 W 118-47-10 W 8511 3-29-63 33-15-30 N 700 f th . 1702 33-13-30 N 680 f th . 1823 275 m 118-37-50 W 118-32-30 W 8512 3-29-63 33-13-54 N 685 f th . 1900 33-20-24 N 670 f t h . 2200 230 m 118-32-54 W 118-39-14 W Appendix I— Continued Sta. S tart Finish Depth No. Date P o sitio n Depth Time P o sitio n Depth Time Fished 3697 5-23-63 33- 26-28 N 700 fth . 1228 33-18- N 1520 1000 118-26-55 W 118-39- W p lu s m 369 3 5-23-63 33- 16-20 N 711 fth . 1815 33-20- N 2100 150 m 118-34-45 W 118-43- W 8700 5-24-63 33-15-30 N 705 fth . 0812 33-20-00 N 1245 850 m 118-33-45 W 118-43-30 W 8702 5-24-63 33-20-32 N 716 fth . 1345 33-16- N 1630 275 m 118-45-30 W 118-37- W 8710 6- 5-63 33-15-15 N 675 fth . 1855 33-19-18 N 690 fth . 2200 550 m 118- 32-58 W 118-39-38 W 8711 6- 6-63 33-18-47 N 700 fth . 0925 33-24-55 N 701 f th . 1230 490 m 118- 39-02 W 118-49-45 W 8712 6- 6-63 33- 25-OO N 711 fth . 1300 33-19-00 N 716 f th . 1630 700 m 118- 50-15 W 118-38-35 W 8713 6- 6-63 33-19-05 N 695 fth . I 656 33-26-07 N 585 f t h . 1927 195 m 118-38-25 W 118-46-21 W 8716 6- 7-63 33-13-45 N 695 fth . 1857 33-17-34 N 720 f th . 2135 425 m 118-32-34 W 118-41-40 W 8717 6- 7-63 33-17-45 N 720 fth . 2203 33-25-45 N 660 fth . 0020 80 m 118-41-22 W 118-43-30 W 8789 7-16-63 33-18-22 N 695 fth . 1703 33-24-31 N 660 fth . 1954 190 m 118-35-40 W 118-43-30 W 202 Appendix I— Continued Sta. No. Date S tart P o sitio n Depth Time Finish P o sitio n Depth Time Depth Fished 3733 7-16-63 33-25-15 N 715 fth . 1359 33-13-15 N 69* fth . 1701 455 m 113-47-10 W 113-37-00 W 3795 7-13-63 . 33-25-23 N 700 fth . 1115 33-13-33 N 690 fth . 1433 770 m 113-51-40 W 113-41-12 W *796 7-13-63 33-13-20 N 690 fth . 1455 33-25-12 N 710 fth . 1818 700 m 113-40-30 W 113-43-40 W 3956 10-16-63 33-24-40 N 700 fth . 2315 33-21-20 N 700 fth . 0022 15 m 113-51-21 W 118- 46-42 W 3957 10-17-63 33-20-45 N 700 fth . 0053 33-17-50 N 695 fth . 0211 50 m 113-46-00 W 118- 40-42 W 3953 10-17-63 33-17-40 N 710 fth . 0249 33-11-45 N 690 fth . 0528 285 m 113-40-15 W 118- 31-12 W 3959 10-17-63 3 3 -U -2 3 N 660 fth . 0633 33-21-32 N 685 fth . 1250 1000 r a 113-29-23 W 118- 47-00 W 3960 10-17-63 33- 22-00 N 705 fth . 1316 33-17-00 N 695 fth . 1542 275 m 113-46-15 W 118- 37-02 W 3961 10-13-63 33-21-27 N 665 f th . 0315 33-15-10 N 670 fth . 1100 450 m 113-40-29 W 118- 32-20 W 3964 10-13-63 33-10-45 N 670 fth . 2353 33-21-54 N 690 fth . 0625 1000 113-30-31 W 118- 46-40 W plus m 9053 11-13-63 33-24-45 N 720 fth . 2224 33- 22-00 N 690 f th . 2340 10 m 113-51-10 W 113-47-10 W 203 Sta. No. 9054 9055 9056 9059 9060 9165 9166 9167 9243 9245 9247 Appendix I— Continued S tart F inish Depth Date P o sitio n Depth Time P o sitio n Depth Time Fished 11- 14-63 33-21-08 N 715 fth . 0013 33-19-10 N 715 fth . 0120 50 118-45-55 W 118-42-48 W 11- 14-63 33-13-55 N 715 fth . 0202 33-13-02 N 700 fth . 0422 150 118-42-10 W 118-33-17 W 11- 14-63 33-12-42 N 695 fth . 0522 33-24-35 N 695 fth . 1200 1100 118-32-15 V 118-52-20 W 11-15-63 33-23-10 N 700 fth . 1055 33-16-31 N 685 fth . 1231 325 118-46-20 W 118-37-12 W 11-15-63 33-16-20 N 685 fth . 1355 33-09-21 N 570 fth . 1922 685 118-35-50 W 118-12-10 W 12-18-63 33-25-13 N 710 fth . 2018 33-18-26 N 700 fth . 2300 400 118-51-31 W 118-43-12 W i 12-18-63 33-18-00 N 690 fth . 2348 33-13-04 N 680 fth . 0300 600 118-42-24 W 118-30-20 W 12-19-63 33-13-30 N 670 fth . 0335 33-19-15 N 712 fth . 0608 200 118-29-52 W 118-37-05 V 7 1- 23-64 33-23-35 N 640 fth . 2110 33-16-13 N 700 f th . 2357 870 118-41-25 W 118-33-01 W 1-24-64 33-17-05 N 700 fth . 0355 33-08-12 N 610 fth . 1006 1000 118-36-40 W 118-20-00 W 1-24-64 33-13-24 N 665 fth . 1325 33-15-40 N 690 fth . 1450 125 118-31-02 W 118-34-17 W 204 Appendix I— Continued Sta. No. Date S tart P o sitio n Depth Time Finish P o sitio n Depth Time Depth Fished 9347 2-12-64 33-23-00 118- 52-36 N W 655 fth . 2246 33-21-10 118-43-27 N W 740 fth . 0135 550 m 9348 2-13-64 33-20-48 118- 43-00 N W 720 fth . 0153 33-15-55 118- 34-00 N W 685 f th . 0423 345 m 9349 2-13-64 33-15-45 118-33-30 N W 680 fth . 0445 33-09-30 118- 23-00 N W 65O f th . 0728 550 m 9350 2-13-64 33-09-00 118- 23-30 N W 650 fth . 0741 33-13-00 118- 31-32 N W 670 fth . 1007 165 m 9598 4-16-64 33- 11-28 118- 27-28 N W 665 f th . 0818 0855 100 m 9599 4-16-64 33-12-40 118-29-48 N W 670 fth . 0915 0955 50 m 9600 4-16-64 33-13-24 118- 32-40 N W 685 fth . 1008 1040 20 m 9601 4- 16-64 33-14-35 118-34-28 N W 700 fth . 1057 1140 100 m 205 Sta. No. 7221 7279 7281 7325 7371 7374 8311 8310 8309 8235 Appendix II S tation Data for San Pedrp'Channel S tart Finish Date P o sitio n Depth Time P o sitio n Depth Time 12- 9-60 33-37-36 N 463 f t h . 1008 33-27-13 N 461 f th . 1510 118-32-28 W 118-17-24 W 2- 2-61 33- 39-25 N 462 fth . 1124 33-25-18 N 436 fth . 1647 118-31-39 W 118-15-16 W 2- 3-61 33-33-12 N 0 to fth . 0148 33-25-44 N 0500 118-23-56 W 118-16-38 W 3- 9-61 33-36-54 N A 60 f t h . 1129 33-24-14 N 447 fth . 1350 118-24-18 W 118-17-44 W 6-28-61 33-38-30 N 452 f th . 1020 33-26-24 N 447 fth . 1605 118-33-18 W 118-16-12 W 6-29-61 33-35-24 N 476 f th . 0200 33-28-00 N 0550 118-29-56 W 118-18-48 W 11- 21-62 33-34-17 N 475 fth . 2323 33- 37-O6 N 470 fth . 0029 118-27-06 W 118-31-56 W 11-21-62 33-30-36 N 478 f t h . 2133 33-34-05 N 478 fth . 2303 118-21-28 W 118-25-03 W 11-21-62 33-35-44 N 0 to f t h . 1908 33-30-28 N 480 fth . 2110 118-28-27 W 118-21-32 W 10-22-62 33-34-02 N 430 fth . 1003 33-37-08 N 470 fth . 1159 118-21-06 W 118-27-45 W Appendix II— Continued Sta. No. Date S tart P o sitio n Depth Time Finish P o sitio n Depth Time Depth Fished 8236 10-22-62 33-37-02 N 470 f t h . 1209 33-33-12 N 478 fth . 1407 520 m 113-27-24 W 118-21-18 W 73 88 3-15-61 33-29-45 N 430 fth . 1350 33-31-57 N 478 fth . 1536 600 m 113-16-39 W 118-23-40 W 7389 3-15-61 33-31-50 N 478 fth . 1600 33-27-23 N 462 fth . 1800 65O m 113-23-32 v; 118-17-53 W 7391 3-15-61 33-31-26 N 478 fth . 2333 33-37-06 N 473 fth . 0133 550 m 113-26-30 W 118-31-42 W S312 11-22-62 33-37-08 N 465 fth . 0102 33-30-44 N 470 fth . 0406 784 m 118-31-42 W 118-23-16 W 8521 4- 5-63 33-36-30 N 475 fth . 0945 33-32-30 N 492 fth . 1211 675 m 118-28-52 W 118-21-25 W 207 LITERATURE CITED LITERATURE CITED ARON, W . 1962. The d istr ib u tio n o f animals in the eastern North P a c ific and i t s re la tio n sh ip to p h y sica l and chemical co n d itio n s. J. F ish er ies Res. Bd. Canada, Vol. 19, ff2, pp. 271-314. ARON, W., RAXTER, N ., NOEL, R ., and ANDREW S, W . 1964. A d escrip tio n o f a d is c r e te depth plankton sampler with some notes on the towing behavior o f a 6 -fo o t Issacs-K idd midwater traw l and a one-meter ring n et. Limnology and Oceanography, Vol. 9, #9, pp. 324-333. BARNARD, K. H. 1930 Amphipoda. B r itish A ntarctic ("Terra Nova") E xpedition, 1910. Natural H ist. R e p t's., Zoology. Vol. 8, #4, Crustacea Part. XI, pp. 307-454, London. _________. 1932. Amphipoda. Discovery Rept’ s . , Vol. 5, pp. 1-326. BARNARD, J. L. 1954- Four sp ecies o f bathypelagic Gammaridea (Amphipoda) from C a lifo rn ia . Allan Hancock Found. P u b lic a tio n s ., Occ. Paper ^13, pp. 52-69. _________ . 1954. Marine Amphipoda from Oregon. Ore. S tate Mongraphs #8, pp. 1-103. _________ . 1957. New bathypelagic amphipods of the general Rhachotropis and L epechinella with keys to the genera. B u ll. So. C a lif. Acad, o f S cien ces, Vol. 56, P t. 1, pp. 14-20. ________ . 1961. Gammaridean Amphipoda from depths o f 400 to 6000 m eters. Galathea R ept., Vol. 5, pp. 23-128. _________. 1962. South A tla n tic ab yssal amphipods. Reprint from Abyssal Crustacea, pp. 1-76. New York: Columbia Univ. P ress. BERNSTEIN, A ., and VINOGRADOV, M . 1955. P elagich esk ie gammaridy (Amphipoda-Gammaridea) Kurilo-Kamchatskoj Vpadiny. Akad, Nauk SSSR, Trudy I n s t. Okean., Vol. 12, pp. 210-287. 209 210 195&- P ela g ich esk ie gammaridy (Amphipoda- Gammaridea) Severo-Zapandnoj Chasti Tixogo Okeana., Akad. Nauk.SSSR, Trudy I n s t, Okean., Vol. 27, pp. 219-257. BIGELOW , H. B. 1926. Plankton of the offsh ore waters of the Gulf o f Maine. B u ll. U. S. Bur. F ish e r ie s, Vol. 40, I I , pp. 1-507. BOECK, A. 1S71. Crustacea Amphipoda b o rea lia e t A rctica. Fohr. (Nordske) V id en sk .-S elsk . (1&70), pp. &3-2BO. BOVALLIUS, C. 1#90. The O xycepjalids. S o cie ta s S cien- tiarum-UpsaTa-Nova Acta, Ser. #3, Vol. 14, pp. 1-141. C A LM A N , W . T. 1#9$. On a c o lle c tio n o f Crustacea from Puget Sound. Annals N. Y. Acad. S c i ., Vol. 11, #13, pp. 259-2S4. CHEVREUX, E. 1905. D escription d’un Amphipode (Cyphocaris rich ard i nov. sp .) provenant des p'eches au f i l e t ouverture de la derniere campagne du yacht "P rincesse- A lic e ” (1904). B u ll. I n s t. Ocean. Monaco, Vol. 24, pp. 1-5. . 1916. Sur le s Amphipodes du genre Cyphocaris Boeck r e c u e i l l i s par la " P rin cesse-A lice” au moyen du f i l e t Richard a grande ouverture. B u ll. I n s t. Ocean. Monaco, Vol. 319, pp. 1-7. _________ et L. Fage. 1925. Amphipodes. Faune de France. P a ris, Vol. 9, pp. l-4 # £ . CLARKE, G. L. 1933* Diurnal m igration of plankton in the Gulf o f Maine and i t s co r rela tio n with changes in submarine ir r a d ia tio n . B io l. B u ll., Vol. 6 5 , pp. 402-436. _________ . 1934. Factors a ffe c tin g the v e r t ic a l d istr ib u tio n of copepods. Ecol. Mono., Vol. 4, pp. 530-540. DIETZ, R. S. 1962. The deep sc a tter in g la y e r s. S c i. Amer. August, 1962. DUNBAR, M. J. 1946. On Themisto lib e l lu la in B affin Island co a sta l w aters. J. Fish. Res. fid. Canada, V ol. 6, pp. 419-434. EM ERY, K. 0. I960. The Sea Off Southern C aliforn ia. New York: J. Wiley and Sons. 211 ESTERLY, C. 0. 1912. The occurrence and v e r t ic a l d istr ib u tio n o f the Copepoda of the San Diego region with p a rticu la r reference to nineteen sp e c ie s. Univ. C a lif. Publ. #9, pp. 253-340. HARKER, J . E. 195&. Diurnal rhythms in the animal kingdom. B io l. Rev., Vol. 33, #1, pp. 1-52. HO LM ES, S. J. 1908. The Amphipoda c o lle c te d by the U. S. Bureau of F ish e r ie s steamer ’•Albatross” o f f the west coast o f North America in 1903 and 1904, with d escrip tio n s o f a new fam ily and several new genera and sp e c ie s. Proc. U. S. Nat’ l . Mus., Vol. 35, pp. 489-543. HURLEY, D. E. 1956. Bathypelagic and other Hyperiidea from C aliforn ia w aters. Allan Hancock Found. Publ. #18, pp. 1-25. _________ . 1963. Amphipoda o f the fam ily L ysianassidae from the west coast o f North and Central America. Allan Hancock Found. Publ. , Occ. Paper #25, pp. 1-160. ISSACS, J. D ., and KIDD, L. W . 1953. Issacs-K idd Midwater Trawl. Scripps I n s t, of Ocean., Ref. 53-3, 21 pp. M ACKINTOSH, N. A. 1934. D istrib u tion o f macroplankton in the A tla n tic sector o f the A ntarctic. Great B r it. Discovery R e p ts., Vol. 9, pp. 67-160. M URRAY, J . , and HJ0RT, J. 1912. The depths o f the ocean. London: Macmillan Co. PERES, J. M ., and DEVEZE, L. 1963. Oceanographie Biologique e t B io lo g ie Marine. V ol. I I . Tome second: La v ie pelagiqu e, pp. 313-330, P resses Univ. de France, 1963. PIRLOT, J. 1929. Les Araphipodes Hyperides. (Res. Zool. de la C roisiere A tlantique de l f”Armauer Hansen.” ) Univ. de L iege, Trav. de l 1In st. Ed. van Beneden, B ru xelles, Vol. 1, pp. 1-196. _________ . 1930. Les Amphipodes de l'E xpd d ition du Siboga. Pt. I , Les Amphipodes H yperiidees. S ib o g a -ex p ed ite, Mono. 33a, pp. 1-54. . 1936. Les Amphipodes de 1 ' Expedition du Siboga. Gammarides. S ib oga-exp ed ite, Mono. 33, a - f , pp. 1-388. 212 RAYM O NT, J. E. G. 1963. Plankton and p ro d u ctiv ity in the oceans. Chapt. XV, V e r tic a l d istr ib u tio n and m igration o f zooplankton, pp. 418- 466. New York: The Macmillan Co. REID, J. L. 1962. Measurement o f the C aliforn ia Counter Current at a depth o f 250 m eters. J. Mar. Res. , Vol.' 2 0, #2 , pp. 134-137. SARS, G. 0. 1895. An account of the Crustacea o f Norway. Vol. I , Amphipoda. SCHELLENBERG, A. 1926. Amphipoda 3 ‘ Die Gammariden der Deutschen T eifsee-E xp ed ition . Wiss. Ergeb. Deutschen T eifsee Exped. "V aldivia” 1898-1899. Vol. 2 3, pp. 195-243. SHEPARD, F. P ., and EM ERY, K. 0. 1941. Submarine topography o f f the C a lifo rn ia coast: Canyons and te c to n ic in te r p r e ta tio n s. Geol. Soc. Amer., Special Papers, #31, 171 pp. SH O EM AK ER, C. 1942. Amphipoda crustaceans c o lle c te d on the P r e s id e n tia l Cruise of 1938. Smithsonian Misc. C o ll., Vol. 101, #11, pp. 1-52. _________ . 1945. The Amphipoda o f the Bermuda Oceani- graphic E xpeditions, 1929-1931. Z oologica, Vol. 29-30, pp. 185- 272. . 1956. Notes on the amphipods Eurythenes g r y llu s (L ich ten stein ) and Katius obesus Chevreux. Proc. B io l. Soc. Wash., Vol. 69, pp. 177-178. STEBBING, T. T. R. 1888. Report on the Amphipoda c o lle c te d by H M S Challenger during the years 1873-1876. The voyage of H M S Challenger, Zoology, Vol. XXIX. _________. 1906. Amphipoda I , Gammaridea. Das T erreich, pp. 1- 8 0 6. STEPHENSEN, K. 1918. Hyperiidea-Amphipoda (part 1 ), D,2. Report on the Danish Oceanographical E xpeditions 1908- 1910 to the Mediterranean and adjacent seas. Vol. I I , B iology, C-D, 3, pp. 3-70. _________ . 1923. Crustacea M alacostraca, V. (Amphipoda I) The Danish In g o lf-e x p e d itio n , Vol. I l l , pp. 1-178. 213 _________ . 1924-1925. Hyperiidea-Amphipoda (p a rts 2 & 3), D, 4. Report on the Danish Oceanographical Expeditions 1908-1910 to the Mediterranean and adjacent seas. Vol. I I , Biology, D, 4-6, pp. 71-252. ________ . 1933. Amphipoda of the Godthaab Expedition 1928 (Denmark). Medd. G ro e n l., Vol. 79, £7, pp. 1-88, SVERDRUP, H. U., JOHNSON, M. W., and FLEMING, R. H. i 9 6 0 . The Oceans. Englewood C lif f s , N. J . : P r e n tis s - H a ll, In c . THORSTEINSON, E. D. 1941. New or noteworthy amphipods from the North P a c ific coast. Univ. Wash. Publ. Oceanography, Vol. 4, #2, pp. 50-94- WAGLER, E. 1926. Amphipoda 2: Scinidae der Deutschen T eifsee-E xpedition. Wiss. Ergeb. Deutschen T eifsee- Exped. Jena. Vol. 20, pp. 319-446. W ATERM ANN, T . , NUNNEMACHER, R ., CHACE, F . , and CLARKE, G. 1939. Diurnal v e r t i c a l m igrations of deep-water plankton. B iol. B ull. Vol. 7 6 , pp. 256-279.

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Creator Brusca, Gary John (author)

Core Title The ecology of the mid-water Amphipoda in the waters over the Santa Catalina and the San Pedro Basins off the coast of southern California

School Graduate School

Degree Doctor of Philosophy

Degree Program Biology

Degree Conferral Date 1965-06

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

Tag biology, zoology,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Zimmer, Russel L. (committee chair), Bakus, Gerald J. (committee member), Garth, John S. (committee member), Gorsline, Donn S. (committee member), Saunders, Paul R. (committee member), Savage, Jay Mathers (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c18-181744

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