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Selenium-mercury relationships in Idaho lake fish versus Northeastern USA lake fish
Citation:
PETERSON, S. A., A. T. HERLIHY, D. Essig, AND A. R. OLSEN. Selenium-mercury relationships in Idaho lake fish versus Northeastern USA lake fish. Presented at SETAC North America 31st Annual Meeting, Portland, OR, November 07 - 11, 2010.
Impact/Purpose:
Methyl-mercury (MeHg) exposure to wildlife and humans occurs primarily through the foodweb, notably fish consumption.
Description:
Methyl-mercury (MeHg) exposure to wildlife and humans occurs primarily through the foodweb, notably fish consumption. Selenium moderates the toxicity of MeHg in all animal models that utilize selenoenzymatic protein synthesis, as do humans. A Se:Hg molar ratio of <1:1 appears to adversely impact selenoenzymatic processes; producing Hg effects while a Se:Hg ratio of >1:1 protects against adverse Hg effects, but at high levels might result in Se effects. Fish containing Se in excess of Hg fed to test animals reduces Hg toxicity effects in the consumers. Thus, fish tissue Se:Hg molar ratios serve as indicators of Hg toxicity potentials. We sampled fish tissue from 50 Idaho lakes and 45 northeastern USA lakes (NELs) ≥20 ha in size using a probability design such that our results are inferable to all 20 ha and larger lakes in the two study regions. Mean filet fish tissue mercury concentrations exceeded the human fish tissue criterion (0.3 ug/g) in 25% of the Idaho lakes and 47% of the Northeastern Lakes. Mercury concentrations were highest in piscivorous fish species (e.g. bass, pike, walleye). Selenium to mercury molar ratios (Se:Hg) were >1:1 in 83% of the fish sampled in Idaho and 75% of the NELs. Among fish species common to both western and northeastern lakes, bass (Micropterus sp.) appear to have the greatest potential mercury toxicity risk to consumers based on their higher mercury content and reduced Se:Hg molar ratios. In Idaho lakes that contained bass, bass filets in 36% of the lakes had a Se:Hg molar ratio <1:1. In NELs that contained bass, less than 14% of the lakes had bass filets with a Se:Hg molar ratio <1:1.