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Cross-ecosystem impacts of stream pollution reduce resource and contaminant flux to riparian food webs

May 1, 2014

The effects of aquatic contaminants are propagated across ecosystem boundaries by aquatic insects that export resources and contaminants to terrestrial food webs; however, the mechanisms driving these effects are poorly understood. We examined how emergence, contaminant concentration, and total contaminant flux by adult aquatic insects changed over a gradient of bioavailable metals in streams and how these changes affected riparian web-building spiders. Insect emergence decreased 97% over the metal gradient, whereas metal concentrations in adult insects changed relatively little. As a result, total metal exported by insects (flux) was lowest at the most contaminated streams, declining 96% among sites. Spiders were affected by the decrease in prey biomass, but not by metal exposure or metal flux to land in aquatic prey. Aquatic insects are increasingly thought to increase exposure of terrestrial consumers to aquatic contaminants, but stream metals reduce contaminant flux to riparian consumers by strongly impacting the resource linkage. Our results demonstrate the importance of understanding the contaminant-specific effects of aquatic pollutants on adult insect emergence and contaminant accumulation in adults to predict impacts on terrestrial food webs.

Citation Information

Publication Year 2014
Title Cross-ecosystem impacts of stream pollution reduce resource and contaminant flux to riparian food webs
DOI 10.1890/13-0252.1
Authors Johanna M. Kraus, Travis S. Schmidt, David Walters, Richard B. Wanty, Robert E. Zuellig, Ruth E. Wolf
Publication Type Article
Publication Subtype Journal Article
Series Title Ecological Applications
Series Number
Index ID 70182103
Record Source USGS Publications Warehouse
USGS Organization Crustal Geophysics and Geochemistry Science Center