2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

5/20/2019 | 2:15 PM - 2:30 PM | FOOD WEB CONTROLS ON MERCURY FLUX AND FATE IN THE COLORADO RIVER, GRAND CANYON | 250 DE

FOOD WEB CONTROLS ON MERCURY FLUX AND FATE IN THE COLORADO RIVER, GRAND CANYON

Mercury (Hg) accumulation in the environment is well studied, but less attention has focused on how species traits and trophic interactions affect the movement of Hg within food webs and between ecosystems. We quantified Hg flows in Colorado River food webs by coupling measures of animal production, gut contents, and tissue Hg concentrations over two years before and after an experimental flood. Hg fluxes to invertebrates were dominated by consumption of amorphous detritus and diatoms. Among aquatic invertebrates, Hg flux to mudsnails was the greatest, but this represented a Hg sink because mudsnails are predator resistant. Blackfly larvae biomass was just ~1% relative to mudsnail biomass, but they were the largest Hg source to fishes because they were preferred prey. Blackflies were also the dominant Hg source for terrestrial predators. However, the fate of Hg accumulated in blackfly tissue (aquatic vs. terrestrial), depended on the degree of match/mismatch between larval blackfly production and their predation rate by fish. By coupling ecotoxicological perspectives with ecosystem energetics, we provide an ecological basis for predicting contaminant fate within and across aquatic-riparian boundaries and new insights on how contaminant flux can govern wildlife exposure.

Aquatic-terrestrial Linkage
Ecotoxicology
Predator-prey

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Presenters/Authors

David Walters (), US Geological Survey, waltersd@usgs.gov;