The distance that contaminated aquatic subsidies extend into lake riparian zones

Ecological Applications
By: , and 



Consumption of emergent aquatic insects by terrestrial invertebrates is a poorly resolved, but potentially important, mechanism of contaminant flux across ecosystem borders leading to contaminant exposure in terrestrial invertivores. We characterized the spatial extent and magnitude of contaminant transfer from aquatic sediments to terrestrial invertebrate predators by examining riparian araneid spiders, terrestrial insects, and emergent aquatic insects for stable isotopes and polychlorinated biphenyls (PCBs, sum of 141 congeners) at Lake Hartwell, (Clemson, South Carolina, USA). PCB concentrations in aquatic insects were orders of magnitude higher than in terrestrial insects. Aquatic insect consumption by spiders (as indicated by δ13C and δ15N), PCB concentrations in spiders, and aquatic prey availability were greatest at the shoreline and declined inland, while terrestrial prey availability was invariant with distance. These patterns indicate PCB transfer to spiders through consumption of emergent aquatic insects extending to a distance of ∼5 m inland. Measurable, but much lower, PCBs were present in insect predators dominated by social wasps up to 30 m inland. These results illustrate the importance of emergent insects as vectors of contaminant transfer from lake sediments to riparian food webs, and that spiders are key predators in this process.

Study Area

Publication type Article
Publication Subtype Journal Article
Title The distance that contaminated aquatic subsidies extend into lake riparian zones
Series title Ecological Applications
DOI 10.1890/09-1504.1
Volume 21
Issue 3
Year Published 2011
Language English
Publisher Ecological Society of America
Description 8 p.
First page 983
Last page 990
Country United States
State South Carolina
Other Geospatial Lake Hartwell
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