Prediction of Effects of Daily Flow Fluctuations on Stream Biota

摘要

The short-term effects of regulated daily discharges on benthos communities were examined in a small Michigan trout stream. Flow regulation designs simulated fluctuations produced by storage and release for hydroelectric generation, as well as different constant daily stream diversions. Impacts on the dynamics of micro-distribution, species diversity, and behavior were evaluated on stable artificial substrates. Invertebrate drift rates were measured at different discharges during light and dark periods. The caddisfly G. nigrior became less active and oriented downstream when exposed to high discharge, and underwent movements to protected substrate faces. The mayfly Baetis vagans also changed micro-positioning in response to flow fluctuations, but total density changes generally were more pronounced. There was evidence for increased species diversity during low discharges.