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(107) Factors affecting mercury and POPs concentrations in lake trout food webs in Canada and northern USA.
Evans, M.*,1, Muir, D.2, Lockhart, L.3, Anderson, M.4, Drouillard, K.5, Fairchild, W.6, Guildford, S.7, Haffner, G.5, Kidd, K.3, Payne, J.4, 1 Environment Canada, National Water Research Institute, Saskatoon, SK2 Environment Canada, National Water Research Institute, Burlington, ON3 Fisheries & Oceans Canada, Freshwater Institute, Winnipeg, MB4 Fisheries & Oceans Canada, St. Johns, NF5 University of Windsor, Windsor, ON6 Fisheries & Oceans Canada, Moncton, NB7 University of Waterloo, Waterloo, ON
ABSTRACT- Mercury and persistent organics (POPs) concentrations vary in top fish predators as a function of biological factors such as food chain length, productivity, and fish age and physical-chemical factors such as lake size, water chemistry, and proximity to sources. Here we report the results of studies investigating mercury and POPs concentrations in predatory fish in a series of lakes ranging from the Northwest Territories and Labrador, New Brunswick, southern Ontario and northern New York state, northwestern Ontario, Saskatchewan, and Alberta. Mercury concentrations in lake trout were strongly related to fish age and inversely related to lake size. Highest mercury levels were observed in the NWT where fish were older and slower growing. High concentration also were observed in reservoir and mining areas in Labrador. Lake size also was important, presumable because of stronger watershed influences. In contrast, POPs concentrations in fish were more strongly related to proximity to atmospheric sources with higher concentrations in southern environments. In the NWT, there was a positive relationship between POPs concentrations and lake size, possibly related to the clearer and low productivity of larger lakes which provided for less dilution capacity of atmospherically derived POPs.
Key words: mercury, POPs, lake size, biomagnification
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