, Volume 5, Issue 3, pp 360–370 | Cite as

Mercury and Selenium in Blood and Epidermis of Bottlenose Dolphins (Tursiops truncatus) from Sarasota Bay, FL: Interaction and Relevance to Life History and Hematologic Parameters

  • Victoria Woshner
  • Katrina Knott
  • Randall Wells
  • Carla Willetto
  • Rhonda Swor
  • Todd O’Hara
Original Contribution


Blood and epidermal biopsies from free-ranging Tursiops truncatus captured and released during either summer or winter health assessments in Sarasota Bay, FL, were evaluated for concentrations of mercury, selenium, stable isotopes (δ13C and δ15N), and blood glutathione peroxidase activity in conjunction with routine hematology and serum chemistry panels. Major objectives were to: 1) quantify and describe relationships among mercury, selenium, glutathione peroxidase, and stable isotopes of C and N in blood and epidermis; 2) elucidate major parameters that influence blood mercury and glutathione peroxidase activity; 3) relate measures of tissue mercury, selenium, and glutathione peroxidase to specific ecological, hematological, morphological, or life history parameters, including season, sex, age, and trophic level. Mercury in both tissues examined is almost exclusively methylmercury. Epidermal concentrations of mercury and selenium reflect their respective amounts in blood, albeit at several times blood concentrations of mercury. The strong association between blood mercury and serum selenium, in conjunction with a lack of significant correlation between blood mercury and glutathione peroxidase, implies that a substantial proportion of blood mercury is affiliated with another selenium-containing moiety or is related to recent dietary intakes (e.g., trophic level, intensive fish consumption). Circulating blood mercury may be described in terms of serum selenium concentration, along with interaction terms among serum selenium, blood δ15N, and age. Current selenium concentrations in Sarasota Bay dolphins appear adequate for maintenance of blood glutathione peroxidase activity. However, dolphins evidently are subject to seasonal exacerbation of oxidative stress, which might render them more vulnerable to toxic effects of mercury.


bottlenose dolphin hematology glutathione peroxidase mercury selenium stable isotopes 



The authors extend sincere gratitude to the staff of the Sarasota Dolphin Research Program based at Mote Marine Laboratory, especially to Brian Balmer and Suzanne Hofmann for help with sample collection and logistics, and to Howard Rhinehart, who helped to initiate this study through his recognition of the importance of selenium in odontocete health. We also thank Ailsa Hall for statistical advice and Nikki Greer for analytical assistance, as well as Debra Miller and Mike Castellini for manuscript review. Special thanks go to the National Oceanic and Atmospheric Administration for support through the Chicago Zoological Society and Dolphin Quest, and to Dr. Teri Rowles of the NOAA Marine Mammal Health and Stranding Response Program. This publication (O’Hara, Knott, Swor) was made possible in part by Grant Number 5P20RR016466 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NCRR or NIH.

Supplementary material

10393_2008_164_MOESM1_ESM.doc (134 kb)
(DOC 134 kb)


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Copyright information

© International Association for Ecology and Health 2008

Authors and Affiliations

  • Victoria Woshner
    • 1
  • Katrina Knott
    • 2
  • Randall Wells
    • 3
  • Carla Willetto
    • 4
  • Rhonda Swor
    • 2
  • Todd O’Hara
    • 2
  1. 1.HillsboroughUSA
  2. 2.Wildlife Toxicology Laboratory, Institute of Arctic Biology, University of Alaska FairbanksFairbanksUSA
  3. 3.Chicago Zoological Society, c/o Mote Marine LaboratorySarasotaUSA
  4. 4.VETSFairbanksUSA

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