SREL Reprint #3474

Trophic strategies influence metal bioaccumulation in detritus-based, aquatic food webs

Nathan J. Tomczyk1,5, Thomas B. Parr2, Elmer Gray3, Joseph Iburg4, and Krista A. Capps1,5

1Odum School of Ecology, University of Georgia, Athens, Georgia United States
2Department of Biology, University of Oklahoma, Norman, Oklahoma United States
3Department of Entomology, University of Georgia, Athens, Georgia United States
4City of Bullhead, Bullhead City, Arizona United States
5Savannah River Ecology Lab, University of Georgia, Aiken, South Carolina United States

Abstract: Metal accumulation in aquatic food webs is mediated by physiochemical parameters of the environment and organismal traits. Trophic strategies influence an organisms' exposure to metal pollution, but links between trophic ecology and exposure to divalent metals are relatively understudied. While organically bound metals are typically considered unavailable for uptake, organisms directly consuming dissolved organic carbon (DOC) and bacteria—via the microbial loop—must also be consuming organically bound metals. Hence, we predicted animals feeding within the microbial loop would accumulate metals through their diet. To test this prediction, we exploited dietary differences between two organisms, Simulium vittatum, a filter-feeding black fly and Hyalella azteca, a shredding detritivore. We exposed both species to three treatments of DOC (labile, recalcitrant, and no additional DOC) that were crossed with exposure to variable copper (Cu) concentrations (2.14 µg L-1) in laboratory microcosms. As predicted, H. azteca experienced a buffering effect by DOC. However, this pattern was not apparent for S. vittatum. Our results highlight the importance of considering trophic strategies when examining the impacts of metal pollution on aquatic communities, and demonstrate the potential for the microbial loop to facilitate metal uptake in freshwater food webs.

SREL Reprint #3474

Tomczyk, N. J., T. B. Parr, E. Gray, J. Iburg, and K. A. Capps. 2018. Trophic strategies influence metal bioaccumulation in detritus-based, aquatic food webs. Environmental Science and Technology 52(20): 11886-11894.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).