Variation of Mercury and other Trace Elements in Polar Bears Associated with Dietary Sources of Carbon and Lipid
An Environment Canada scientist collaborated with Canadian and international researchers to investigate the influence of dietary carbon and lipid sources on regional differences in liver trace element (As, Cd, Cu, total Hg, Mn, Pb, Rb, Se, and Zn) concentrations measured in polar bears.
Carbon and lipid sources were determined using carbon isotope ratios in muscle tissue and fatty acid profiles in subcutaneous adipose tissue as chemical tracers in polar bears from ten Alaskan, Canadian Arctic and East Greenland subpopulations. Results suggested that polar bears feeding in areas with higher riverine (freshwater) inputs of carbon accumulate more mercury than bears feeding in areas with lower freshwater input. Mercury concentrations were also positively related to the specific fatty acid found in Calanus copepods, a food of polar bear prey. This result raised the hypothesis that Calanus glacialis are an important link in the uptake of mercury in the marine food web, and ultimately in polar bears. Based on these findings it was suggested that dietary carbon and lipid sources for polar bears should be taken into account when assessing spatial and temporal trends of long-range transported trace elements.
Source: Routti, H., R.J. Letcher, E.W. Born, M. Branigan, R. Dietz, T.J. Evans, M.A. McKinney, E. Peacock and C. Sonne. 2012. Influence of carbon and lipid sources on variation of mercury and other trace elements in polar bears (Ursus maritimus). Environ. Toxicol. Chem. Accepted.
Contact: Dr. Robert Letcher, 613-998-6696, Ecotoxicology and Wildlife Health Division
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