Mercury Concentrations in Hair from Neonatal and Juvenile Steller Sea Lions (Eumetopias jubatus): Implications Based on Age and Region in this Northern Pacific Marine Sentinel Piscivore
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Mercury is a global contaminant of concern for the fetus and the neonate of piscivores. Methylmercury, produced within marine ecosystems, is of particular concern as a readily absorbed neurotoxicant transported across the blood brain barrier and transplacentally. In the North Pacific Ocean, Steller sea lions are broadly distributed apex predators and, as such, integrate complex food webs and the associated exposure and possible adverse effects of toxic and infectious agents. Hair, including lanugo, was examined using regional and age groupings to assess mercury concentrations in young Alaskan Steller sea lions. The highest concentrations of mercury occurred in the youngest animals, likely via in utero exposure. Based on the adverse developmental outcomes of methylmercury toxicity this specific cohort is of concern. Regionally, higher concentrations of mercury were observed in the endangered western population of Steller sea lions and mirrored patterns observed in human biomonitoring studies of Alaskan coastal communities. These data have broader implications with respect to human and ecosystem health as Steller sea lions rely on similar prey species and foraging areas as those targeted by commercial fisheries and subsistence users and are therefore valuable sentinels of marine ecosystem health.
Keywordsmercury methylmercury hair neonate pup marine sentinel Steller sea lion toxicology ecotoxicology ecosystem health
We thank the field research teams of both the Alaska Department of Fish and Game and the National Marine Mammal Laboratory (NMFS/NOAA), the staff of the Alaska SeaLife Center (ASLC), and the crews of the R/V Medeia, P/V Stimson, P/V Wolstad, R/V Tiglax, M/V Pacific Star, and the R/V Norseman. We thank Darce Holcomb of the Wildlife Toxicology Laboratory, University of Alaska Fairbanks, for assistance with sample analysis and Tom Gelatt of the National Marine Mammal Laboratory for providing manuscript comments. Funding has been provided through NOAA Cooperative Agreements NA17FX1079, NA04NMF4390170, and NA07NMF4390312. In addition, this publication was made possible by Grant Number 5P20RR016466 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH). Sample collection described here was part of ongoing Steller sea lion research conducted by the Alaska Department of Fish and Game, The National Marine Mammal Laboratory and the Alaska SeaLife Center under MMPA permits #358-1564, 358-1769, 358-1888, 782-1889, and 881-18900-02 and under ADFG ACUC #03-002 and #06-07 and ASLC IACUC Protocol 07-001.
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