![]() ![]() Predictions of Hg concentrations in aquatic ecosystems and the biota that inhabit them are hampered by complex, interacting factors that can operate at varying spatial scales and confound simplistic predictive models. While it is important to characterize fish burdens of Hg to assess human and wildlife consumption risk, fish are labor-intensive to collect and few species are ubiquitous across streams, lakes, and wetlands, suggesting that the development of common aquatic macroinvertebrates as biosentinels could be useful for research and monitoring. These studies of biological endpoints have most often focused on fish, and their bird or mammal predators. As a result, Common loon populations have been found to be moderately to highly at risk in the region ( Kamman et al. Areas in the Adirondack mountains, NH and ME have been identified as Hg hotspots ( Evers et al. Fish in northeast lakes are particularly prone to higher Hg concentrations due to poorly buffered waters, low levels of human impact resulting in oligotrophy, large areas of forest, and high concentrations of dissolved organic carbon ( Kamman et al. ![]() ![]() In the northeastern US, Hg ‘hotspots’ have been identified using wildlife and human consumption benchmarks ( Evers et al. ![]() Fish with Hg concentrations exceeding human and wildlife consumption guidelines have been documented across the US, even in remote areas that are distant from emission sources (e.g., Eagles-Smith et al. Mercury (Hg) is a globally distributed contaminant that bioaccumulates in foodwebs in its more toxic organic form, methylmercury (MeHg). BAFs declined with increasing DOC, supporting a potential limiting effect for MeHg bioavailability with higher DOC. Dragonfly THg Bioaccumulation Factors (BAFs, calculated as :) increased as lake volume increased, suggesting that lake size influences Hg bioaccumulation or biomagnification. Lakewater DOC and lake volume were strong predictors for MeHg in water. Using landscape, lake chemistry, and lake morphometry data, we evaluated relationships with MeHg in lake water and THg in dragonfly larvae. Aqueous MeHg and dragonfly THg were similar between the Adirondack and Northeast regions, but a majority of lakes within the highest quartile of dragonfly THg were in the Adirondacks. Dragonfly larvae total mercury ranged from 0.016–0.918 μg/g, dw across the study area Adirondack lakes had the minimum and maximum concentrations. Aqueous dissolved organic carbon (DOC) and total Hg (THg) were strongly related to MeHg in lake water. EPA Long-Term Monitoring Network, including 45 lakes in New York, 43 of which are in the Adirondacks. We sampled lake water and dragonfly larvae in 74 northeastern US lakes that are part of the U.S. Dragonfly larvae can serve as biosentinels for Hg given that they are widespread in freshwaters, long-lived, exhibit site fidelity, and bioaccumulate relatively high mercury concentrations, mostly as methylmercury (88% ☑1% MeHg in this study). Resource managers’ efforts to develop fish consumption advisories for humans and to focus conservation efforts for fish-eating wildlife are hampered by spatial variability. Mercury (Hg) is a toxic pollutant, widespread in northeastern U.S. ![]()
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