John Wiley & Sons, Ltd.

Cross‐basin comparison of mercury bioaccumulation in lake Huron lake trout emphasizes ecological characteristics

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Understanding factors influencing mercury (Hg) bioaccumulation in fish is important for examining both ecosystem and human health. However, little is known of how differing ecosystem and biological characteristics can drive Hg bioaccumulation in top predators. This study compared and contrasted Hg bioaccumulation in multiple age classes of lake trout (Salvelinus namaycush) collected from each of Lake Huron's Georgian Bay, North Channel and Main Basin regions. Hg concentrations exhibited a basin specific pattern with Main Basin fish having the highest average concentration (0.19 ± 0.01 mg/kg) followed by Georgian Bay (0.15 ± 0.02 mg/kg) and North Channel (0.07 ± <0.01 mg/kg) fish. Age‐related increases in Hg concentrations were observed across the three basins with North Channel fish exhibiting the slowest rate of Hg bioaccumulation. No significant difference was determined between the relationships describing Hg concentration and age between Main Basin and Georgian Bay fish (p <0.05). Hg biomagnification factors (BMF) determined between lake trout and rainbow smelt, their primary prey, were significantly correlated with fish age and differed across the three basins (p <0.05). Specifically, Georgian Bay fish exhibited the greatest age related increase in Hg BMF followed by Main Basin and North Channel fish and these differences could not be attributed to trophic level (δ15N) effects or lake trout growth rates. A highly significant negative relationship was determined between Hg BMFs and basin specific prey fish densities indicating that ecological factors associated with food acquisition and foraging efficiencies play an important role in Hg bioaccumulation in feral fish communities. This article is protected by copyright. All rights reserved

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