title: Mercury and Selenium Balance in Endangered Saimaa Ringed Seal Depend on Age and Sex.
abstract: The endangered Saimaa ringed seal (Pusa hispida saimensis) 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.
authors.affiliation: Department of Biology, University of Eastern Finland , P.O. Box 111, FIN-80101 Joensuu, Finland.
authors.forename: Merja
authors.initials: M
authors.lastname: Lyytikäinen
authors.affiliation: Department of Biology, University of Eastern Finland , P.O. Box 111, FIN-80101 Joensuu, Finland.
authors.forename: Juuso
authors.initials: J
authors.lastname: Pätynen
authors.affiliation: Department of Biology, University of Eastern Finland , P.O. Box 111, FIN-80101 Joensuu, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Hyvärinen
authors.affiliation: Parks & Wildlife Finland of Metsähallitus , Akselinkatu 8, FIN-57130 Savonlinna, Finland.
authors.forename: Tero
authors.initials: T
authors.lastname: Sipilä
authors.affiliation: Department of Biology, University of Eastern Finland , P.O. Box 111, FIN-80101 Joensuu, Finland.
authors.forename: Mervi
authors.initials: M
authors.lastname: Kunnasranta
mesh_terms: D000367:Age Factors; D000818:Animals; D056727:Endangered Species; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D005387:Finland; D005618:Fresh Water / Q000737:chemistry; D006197:Hair / Q000737:chemistry / Q000378:metabolism; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008628:Mercury / Q000378:metabolism / Q000493:pharmacokinetics* / Q000633:toxicity; D009132:Muscles / Q000737:chemistry / Q000378:metabolism; D046048:Seals, Earless / Q000378:metabolism*; D012643:Selenium / Q000378:metabolism / Q000493:pharmacokinetics* / Q000633:toxicity; D014018:Tissue Distribution; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury; D012643:Selenium