James T. Harvey J. Margaret Castellini Craig A. Stricker Todd M. O'Hara Elizabeth A. McHuron 2014 We measured total selenium and total mercury concentrations ([TSe] and [THg]) in hair (n = 138) and blood (n = 73) of harbor seals (<i>Phoca vitulina</i>) from California to assess variation by geography and sex, and inferred feeding relationships based on carbon, nitrogen, and sulfur stable isotopes. Harbor seals from Hg-contaminated sites had significantly greater [THg], and lesser [TSe] and TSe:THg molar ratios than seals from a relatively uncontaminated site. Males had significantly greater [THg] than females at all locations. Sulfur stable isotope values explained approximately 25% of the variability in [THg], indicating increased Hg exposure for seals with a greater use of estuarine prey species. Decreased [TSe] in harbor seals from Hg-contaminated regions may indicate a relative Se deficiency to mitigate the toxic effects of Hg. Further investigation into the Se status and the potential negative impact of Hg on harbor seals from Hg-contaminated sites is warranted. application/pdf 10.1016/j.marpolbul.2014.04.031 en Elsevier Selenium and mercury concentrations in harbor seals (Phoca vitulina) from central California: Health implications in an urbanized estuary article