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B-VITAMINS AND TRACE METALS IN THE PACIFIC OCEAN: AMBIENT DISTRIBUTION AND BIOLOGICAL IMPACTS by Emily Ann Smail A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (BIOLOGICAL SCIENCES) December 2012 Copyright 2012 Emily Ann Smail
|Title||B-vitamins and trace metals in the Pacific Ocean: ambient distribution and biological impacts|
|Author||Smail, Emily Ann|
|Degree||Doctor of Philosophy|
|Degree program||Marine and Environmental Biology|
|School||College of Letters, Arts And Sciences|
|Advisor (committee chair)||
Sanudo-Wilhelmy, Sergio A.
Sañudo-Wilhelmy, Sergio A.
|Advisor (committee member)||
Webb, Eric A.
Caron, David A.
Berelson, William M.
|Abstract||B-vitamins and trace metals have been implicated as important controllers of phytoplankton abundance and composition in the marine environment. In order to further establish the distribution and biological importance of dissolved B-vitamin in the Pacific Ocean, I determined the environmental concentrations of B-vitamins, the vitamin B12-dependent amino acid methionine, and the B12-precursor cobalt in the Eastern Tropical Pacific (ETSP) and the subtropical North Pacific. The environmental relevance of some toxic trace metals was also established in the coastal ocean off Los Angeles, CA. The field data was complemented with targeted laboratory and field manipulation experiments to assist in the interpretation of environmental distributions. In the ETSP, I collected and analyzed depth-profile measurements of B12, methionine, B7, B6, and cobalt at 6 stations with environmental conditions ranging from nutrient rich coastal stations to oligotrophic open ocean stations. Vitamin B12 and methionine showed similar geographical distributions suggesting a potential control of vitamin B12 on the synthesis of the amino acid likely due to B12-dependent methionine synthase. Despite low cobalt levels in the ETSP (<20pM), vitamin B12 distribution was only related to the trace metal’s distribution in a nutrient rich coastal station suggesting that cobalt may only regulate B12 in locations where other key macronutrients are plentiful. Vitamin B6 showed a strong correlation with chlorophyll indicating that this vitamin may be related to photosynthetic activity. Vitamin B7 showed a coastal input and incubation experiments showed that some phytoplankton may be limited by vitamin B7 in this region. Large areas of the ETSP were depleted of B-vitamins and vitamin concentrations were not clearly correlated with microbial abundance. ❧ In the subtropical North Pacific, the availability of dissolved thiamin (vitamin B1) was related to nitrogen fixation rates due to the genomically identified thiamin auxotrophy of abundant group A cyanobacteria. Field B1 amendment incubation experiments showed a 46% increase in nitrogen fixation and laboratory culture studies with an identified B1 auxotroph showed a 127% increase in nitrogen fixation. ❧ Finally in the Los Angeles coastal ocean, the distribution of dissolved and particulate trace metals was examined in order to establish current levels of trace metal contamination in this region of the Pacific Ocean. Particulate levels were shown to be reduced dramatically compared to levels reported in the 1970s with decreases of ~100-fold for Pb and ~400-fold for Cu and Cd. Dissolved levels were found to be low with concentrations within the same range as an uncontaminated site in Punta Banda, Mexico. A trace metal uptake experiment with Synechococcus sp. CC9311 showed rapid internalization of multiple metals (within 3 hours) highlighting the importance of monitoring environmental concentrations of toxic and nutrient metals in the marine environment.|
|Keyword||B-vitamin; thiamin; unicellular diazotroph; nitrogen fixation; trace metal; Clean Water Act; urban ocean; water contamination; auxotrophy|
|Part of collection||University of Southern California dissertations and theses|
|Publisher (of the original version)||University of Southern California|
|Place of publication (of the original version)||Los Angeles, California|
|Publisher (of the digital version)||University of Southern California. Libraries|
|Provenance||Electronically uploaded by the author|
|Legacy record ID||usctheses-m|
|Contributing entity||University of Southern California|
|Rights||Smail, Emily Ann|
|Physical access||The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given.|
|Repository name||University of Southern California Digital Library|
|Repository address||USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA|
|Contributing entity||University of Southern California|
|Full text||B-VITAMINS AND TRACE METALS IN THE PACIFIC OCEAN: AMBIENT DISTRIBUTION AND BIOLOGICAL IMPACTS by Emily Ann Smail A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (BIOLOGICAL SCIENCES) December 2012 Copyright 2012 Emily Ann Smail|