Health Implications of Mercury, Selenium, and a Red Pelage
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San Jose State University SJSU ScholarWorks Master's Theses Master's Theses and Graduate Research Spring 2012 Health implications of mercury, selenium, and a red pelage in Pacific ah rbor seals (Phoca vitulina richardii) off central California Elizabeth Alexis McHuron San Jose State University Follow this and additional works at: https://scholarworks.sjsu.edu/etd_theses Recommended Citation McHuron, Elizabeth Alexis, "Health implications of mercury, selenium, and a red pelage in Pacific ah rbor seals (Phoca vitulina richardii) off ec ntral California" (2012). Master's Theses. 4148. DOI: https://doi.org/10.31979/etd.drcb-ccf4 https://scholarworks.sjsu.edu/etd_theses/4148 This Thesis is brought to you for free and open access by the Master's Theses and Graduate Research at SJSU ScholarWorks. It has been accepted for inclusion in Master's Theses by an authorized administrator of SJSU ScholarWorks. For more information, please contact [email protected]. HEALTH IMPLICATIONS OF MERCURY, SELENIUM, AND A RED PELAGE IN PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDII) OFF CENTRAL CALIFORNIA A Thesis Presented to The Faculty of Moss Landing Marine Laboratories San José State University In Partial Fulfillment of the Requirements for the Degree Master of Science by Elizabeth A. McHuron May 2012 © 2012 Elizabeth A. McHuron ALL RIGHTS RESERVED The Designated Thesis Committee Approves the Thesis Titled HEALTH IMPLICATIONS OF MERCURY, SELENIUM, AND A RED PELAGE IN PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDII) OFF CENTRAL CALIFORNIA by Elizabeth A. McHuron APPROVED FOR MOSS LANDING MARINE LABORATORIES SAN JOSÉ STATE UNIVERSITY May 2012 Dr. James T. Harvey Moss Landing Marine Laboratories Dr. Leslee A. Parr San José State University Dr. Todd M. O’Hara University of Alaska Fairbanks ABSTRACT HEALTH IMPLICATIONS OF MERCURY, SELENIUM, AND A RED PELAGE IN PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDII) OFF CENTRAL CALIFORNIA by Elizabeth A. McHuron San Francisco Bay (SFB) is the largest estuary on the west coast of the United States. It provides habitat for many species, although is heavily urbanized with a history of selenium (Se) and mercury (Hg) contamination. Harbor seals (Phoca vitulina) are good indicators of the health of SFB because they are long-lived, upper-level trophic consumers, and present in the estuary year-round. The objective of this study was to examine the role of Se and Hg contamination on the health of harbor seals in this region, and the role of Se in the development of a red pelage. Between 2009 and 2011, free- ranging seals (n = 146) were sampled at three sites off central California. Harbor seals from SFB and Tomales Bay had greater total Hg (THg) and lesser Se concentrations in hair than seals from Elkhorn Slough. Differences in THg concentrations with location were likely the result of historic gold and Hg mining. Lesser Se concentrations in seals from SFB and Tomales Bay may indicate that these seals have a greater physiologic requirement for Se due to increased Hg exposure. Concentrations of THg measured in this study may be great enough to negatively impact the health of harbor seals; however, seals in SFB did not appear to suffer from chronic Se toxicosis. The development of a red pelage may be the result of external iron deposition because of increased dependence on benthic prey and does not appear to have any short-term health implications. ACKNOWLEDGEMENTS First and foremost I would like to thank my advisor, Jim Harvey, for the effort and time he put into my education and thesis, for pushing me to be independent, and for always bringing the sunshine. My committee member, Todd O’Hara, for opening his lab and home to me, and for always providing constructive criticism and support. My committee member, Leslee Parr, for being so supportive and always believing in me. Thanks to the countless volunteers that helped out with capturing seals and collecting samples, and to the students, faculty, and staff at MLML for their help and support with my education and this project. The following people were especially helpful in multiple aspects of this project including sample collection, analysis, and entertainment: Stephanie Hughes, Suzanne Manugian, Casey Clark, Deasy Lontoh, Scott Hansen, Alex Olson, Sean Hayes, Denise Greig, Maggie Castellini, Bill Watson, Sarah Tanner, and Michelle Drake. Lastly, I would like to thank my parents and my husband for making all of this possible. Thanks to the Packard Foundation, the Earl and Ethel Myers Oceanographic and Marine Biology Trust, the PADI foundation, COAST, and the Harvey Fellowship for providing funding for this project. This project also would not have been possible without support from the National Parks Service, Don Edwards National Wildlife Refuge, The Marine Mammal Center, MLML, the Wildlife Toxicology Lab, Craig Stricker, and Melissa Miller. v TABLE OF CONTENTS List of Figures....................................................................................................................vii List of Tables.......................................................................................................................ix Introduction..........................................................................................................................1 Chapter I: Mercury and selenium concentrations in hair and relationship with stable isotopes for Pacific harbor seals (Phoca vitulina richardii) off central California..............4 Abstract................................................................................................................................5 Introduction..........................................................................................................................6 Methods..............................................................................................................................12 Sample collection...................................................................................................12 Sample analysis......................................................................................................14 Data analysis..........................................................................................................17 Results................................................................................................................................19 Discussion..........................................................................................................................30 Literature Cited..................................................................................................................48 Chapter II: Red-pelaged harbor seals (Phoca vitulina richardii) in San Francisco Bay: prevalence, potential causes, and health implications.......................................................60 Abstract..............................................................................................................................61 Introduction........................................................................................................................62 Methods..............................................................................................................................67 Prevalence..............................................................................................................67 Sample collection...................................................................................................69 Morphometric analyses..........................................................................................72 Blood analyses.......................................................................................................73 Skin biopsies..........................................................................................................75 Hair analyses..........................................................................................................76 Results................................................................................................................................78 Discussion..........................................................................................................................88 Literature Cited................................................................................................................103 Conclusions......................................................................................................................109 Literature Cited................................................................................................................111 vi LIST OF FIGURES Chapter I: Figure 1. Location and number of harbor seals sampled (denoted by black dots sized relative to sample size) in central California between August 2009 and February 2011.............................................................................................13 Figure 2. Mean total mercury concentrations (THg; µg/g dry wt) in hair of harbor seals from Elkhorn Slough (ES), San Francisco Bay (SFB), and Tomales Bay (TB).......................................................................................20 Figure 3. Relationship between total mercury concentration (THg; µg/g dry wt) in hair and standard length (cm) in harbor seals from San Francisco Bay and Tomales Bay (r2 = 0.006, P = 0.420)..........................................................21 Figure 4. Relationship between total mercury concentration (THg; µg/g dry wt) in hair and standard length (cm) in harbor seals from Elkhorn