1 research outputs found
Mercury and Selenium Balance in Endangered Saimaa Ringed Seal Depend on Age and Sex
The
endangered Saimaa ringed seal (<i>Pusa hispida saimensis</i>) is exposed to relatively high concentrations of mercury (Hg) in
freshwaters poor in selenium (Se), a known antagonist of Hg. The impact
of age and sex on the bioaccumulation of Hg and Se was studied by
analyzing liver, muscle, and hair samples from seals of different
age groups. Adult females were found to accumulate significantly more
Hg in the liver (with ca. 60% as HgSe), and less Hg in the muscles
compared to adult males, which may be explained by accelerated metabolism
during gestation and lactation. In adult seals, molar Se:Hg ratios
in the muscles fall below one, which is considered a threshold for
the emergence of adverse effects. As a result, Saimaa ringed seals
may be at risk of developing health and reproductive problems. According
to mass balance calculations, the pups are exposed to considerable
amounts (μg/d) of mercury during gestation, although lactation
is their main exposure route. In lanugo pups, Hg concentrates in the
hair, and molting serves as a main detoxification route. For other
age groups, demethylation followed by the formation of HgSe is the
main detoxification route, and the demethylation capability develops
in pups by the time of weaning