The influence of copper exposure on predator-prey interactions in aquatic insect communities

1. Vulnerability of two species of net‐spinning caddisflies (Chimarra sp. and Hydropsyche morosa) to predation by the stonefly, Paragnetina media, was significantly greater in experimental streams dosed with copper (target concentration=6 μg 1‐1) than in control streams. 2. Results of stomach analyses showed that Hydropsychidae was the major component of stonefly diets in experimental streams and that the number of Hydropsychidae per stonefly gut was significantly greater in dosed streams than controls. 3. Since these results could not be predicted using single species bioassays, we suggest that such simple tests be supplemented with more environmentally realistic procedures that account for species interactions.