Structural alterations in aquatic insect communities exposed to copper in laboratory streams

Abstract

The effects of copper on aquatic insect communities were examined using rock-filled trays colonized in the field for 30 d, transferred to laboratory streams, and dosed with CuSO4. Each stream was randomly assigned to one of three treatments: control (0 μg/L), low dose (15–32 μg/L), and high dose (135–178 μg/L). Experiments were replicated over three seasons. Exposure to copper for 96 h significantly reduced both the total number of individuals and number of taxa during each season, with greatest effects observed in summer. Owing to differences in sensitivity to copper, the percent composition of dominant orders of aquatic insects varied among treatments. The relative abundance of Ephemeroptera decreased in treated streams during each season. The response of other aquatic insects, including Diptera and Plecoptera, varied between seasons, but these groups were generally less sensitive to copper exposure. These results indicate that the artificial substrates employed in this study are amenable to experimental manipulation and will provide a unique opportunity to examine the community responses of aquatic insects to toxicants under environmentally realistic conditions.