John Wiley & Sons, Ltd.

Species‐specific mercury bioaccumulation in a diverse fish community

Mercury bioaccumulation models developed for fish provide insight into the sources and transfer of Hg within ecosystems. Mercury concentrations were assessed for 16 fish species of the western reach of Lake Diefenbaker, Saskatchewan, Canada. For top‐predators (northern pike Esox lucius, walleye Sander vitreum), Hg concentrations were positively correlated to δ15N, and δ15N to fish age suggesting that throughout life these fish fed on organisms with increasingly higher trophic values and Hg concentrations. However, fish mass was the principal parameter related to Hg concentration for piscivore species, while fish age was the most significant parameter related to Hg concentration in 3 of 6 lower trophic level fish species. For 9 common species combined, individual variation in Hg concentration was explained in declining order of importance by fish mass, trophic position (δ15N) and fish age. Delta 15N value was not the leading variable related to Hg concentration for the assemblage probably because of the longevity of lower trophic level species (three species ≥ 20 yr), substantial overlap in Hg concentration and δ15N values for large‐bodied fish up to 3000 g, and complex relationships between Hg concentration and δ15N among species. These results suggest that the quantity of food (and Hg) consumed each year and converted to fish mass, the quantity of Hg bioaccumulated over years and decades, and trophic position were significant determinants of Hg concentration in Lake Diefenbaker fish. This article is protected by copyright. All rights reserved

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