Does variable flow regime, produced by an overflow dam, alter downstream fish communities in a Midwestern stream?
Both natural and human induced disturbances, such as floods, have long been recognized as having adverse effects on the abiotic and biotic components of streams. Flood disturbances can hinder the predator-prey interactions that usually shape a community, influence reproductive timing and frequency, and physically injure and displace individual organisms within the stream. In 1920, a dam was built on the Sangamon River located in Cumberland County, Illinois to create Lake Decatur. With the building of the dam, a large number of variable flood disturbances have occurred in the central part of the Sangamon River over the past 84 years. From 1998-99 and then from 2001-2002, an intensive sampling program was initiated to document temporal and spatial heterogeneity of an 8.5 km urban reach of the Sangamon River beginning just below Lake Decatur Dam and extending downstream to incorporate discharges from the Sanitary District of Decatur (SDD). The study was designed to characterize stream hab
