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The dark side of suibsidies: quantifying contaminant exposure to riparian predators via stream insects
Citation:
WALTERS, DAVID M., K. M. FRITZ, AND R. R. Otter. The dark side of suibsidies: quantifying contaminant exposure to riparian predators via stream insects. Presented at North American Benthological Society, Salt Lake City, UT, May 25 - 30, 2008.
Impact/Purpose:
The objective of this task is to address the risk management LTG for the Contaminated Sites Research Program in the area of contaminated sediments. The contaminated sediments LTGs of “How can we better assess and document the short- and long-term effectiveness of remediation approaches (e.g., dredging vs capping vs monitored natural attenuation (MNA)?” and “How can any short-term negative impacts from the use of one of these options be reduced?” are partially addressed under this task. The research areas in this task includes: the miniturization of sediment toxicity tests & elutriate comparability with whole sediment assays; and bioassays, development and demonstration of ecological tools for sediment monitoring to assess toxicity, gene expression ecological impacts and the use of stable isotope analysis, to develop a mechanistic understanding of energy and material flux within PCB contaminated streams and lakes and their food webs. Stable isotopes techniques will be used to track biomagnification of PCBs and other persistent bioaccumulative contaminants in lake food and stream food webs using a site based approach in collaboration with other ORD labs' contaminanted sediment research.
Description:
Aquatic insects provide a critical nutrient subsidy to riparian food webs, yet their role as vectors of contaminants to terrestrial ecosystems is poorly understood. We investigated relationships between aquatic (resource utilization) and contaminant exposure for a riparian invertivore assemblage (spiders and herptiles) along a stream contaminated with polychlorinated biphenyls (PCBs). Stable carbon and nitrogen isotopes indicated that aquatic insect utilization varied among predators, with gradual enrichment of stable carbon and depletion of nitrogen as predators shifted from aquatic to terrestrial prey.