University of Illinois at Urbana-Champaign. Water Resources Center
Abstract
Stream flow characteristics, in particular velocity and depth, control channel substrates and directly or indirectly determine how aquatic insects are distributed and benthic communities are structured. A three year laboratory and field research program has been completed evaluating how streamflow affects aquatic insects in Illinois. Field studies related benthic community structure and species composition with boundary layer Reynolds number (R*) and evaluated microhabitat selection of several insect species on hydraulically defined artificial substrates. Hydraulic calibration of substrates was completed in laboratory flume studies using a thermistor based microprobe. A laboratory artificial stream was also used to determine habitat selection of net spinning caddisflies. Results indicated selection for defined microhabitats in several aquatic insect taxa. The artificial substrates proved to be a valuable tool in defining microhabitat characteristics occupied by aquatic insects. In studies to determine instream flow requirements, measures of mean column velocity were shown to be inadequate, determination of R* was preferred. The results of this research provide water resources managers with better tools to assess microhabitat modifications produced by changes in streamflow.U.S. Department of the InteriorU.S. Geological SurveyOpe
