• Regional variations and drivers of mercury and selenium concentrations in Steller sea lions
    • Lorrie Rea (Professor, WERC)
    • March 30, 2018
  • Image above: ADF&G MMPA permit # 358-154.

Abstract

One factor for lack of recovery of endangered Steller sea lions (SSL, Eumetopias jubatus) in parts of Alaska may be low natality. Mercury exposure can be neurotoxic to piscivorous mammals and impact reproduction. We measured total mercury concentration ([THg]) in lanugo (pelage grown in utero) of 839 young SSL pups to assess fetal exposure during late gestation. We measured the molar ratio of total selenium to THg (TSe:THg) in whole blood collected from 291 pups to assess potential protection from Se to the adverse effects of Hg. Finally we measured stable isotope ratios of carbon and nitrogen in sections of vibrissae (whiskers, n = 498) of pups grown during late gestation (and in lanugo, n = 480) to track diet variations between adult females that likely drives Hg exposure during this critical fetal development period.

Lanugo [THg] ranged from 1.4 to 73.7 µg/g dw with the lowest median [THg] in Southeast Alaska. Pups sampled on Attu Island (Western Aleutian Islands, WAI, n=18) and on Seguam Island (Central Aleutian Islands, CAI, n=51) had significantly higher median [THg] in lanugo than pups at all other rookeries except Kozlova Cape (Russia, n=31). Whole blood molar TSe:THg was significantly lower in the WAI suggesting there may be a limitation on the potential protective function of Se in these western regions with the highest [THg].


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