A comparative study of fish communities associated with Newbury weir riffles and pools in Jo Daviess County, Illinois

One problem impacting natural waterways and their watershed is sedimentation and erosion. In order to moderate the problem of bank erosion and sedimentation many bank stabilization techniques have been implemented. One such bank stabilization technique that has gained popularity of late is Newbury weir construction.;The structure is designed to neutralize stream flow (force) that leads to erosion, but creates habitat that resembles pool-riffles in natural streams. During low discharge water is stored above the riffle in a pool, which provides deeper water that is important for fish throughout their life stages. The riffles create obstacles and cause water to flow through narrow gaps between the riprap. Although these structures perform well at bank stabilization, little effort has gone into studying their effect on the stream biota.;An electric seine was used to assess species diversity and fish community similarities between Newbury weir riffle and pool habitats in four streams throughout Jo Daviess County, Illinois. A total of 3,706 fish representing 23 species from 6 families was sampled.;The data revealed no significant difference in species diversity between Newbury weir riffle and pool habitats; however there was a difference in species composition of the fish communities. This study demonstrates that different fish communities are utilizing and inhabiting the Newbury weir riffle and pool habitats, even though there is no difference in fish diversity throughout the streams. Without these riffle habitats created by the Newbury weirs, many of the fish species which are unique and have a limited distribution throughout Illinois would probably experience a decrease in numbers in these streams.