CHAMPAIGN, Ill. - Issues of water quality and ecological diversity in rural Illinois waterways have gained new importance with recent citizens-based efforts to develop comprehensive
watershed-management plans. At the University of Illinois, researchers are developing new tools and techniques to better understand the relevant scientific issues and incorporate them into local decision making.
"By carefully identifying habitats based upon the form and structure of a stream, and then relating the fisheries to those habitats, we can produce better information that will assist local decision makers," said Bruce Rhoads, a professor of geography at the U. of I. "One of our goals is to devise innovative approaches for the maintenance of stream channels that will preserve and enhance biological diversity."
Prior to settlement, Illinois contained vast areas of natural wetlands, most of which were drained for agricultural production. The transformation dramatically modified geomorphological and ecological conditions associated with the rivers and streams. An ongoing debate has focused on how these modified waterways should be maintained, or whether they should be restored.
"Stream restoration means a return to predisturbance conditions, but given the value of the land for agriculture and the ongoing need to provide adequate drainage, the possibility of complete restoration is remote," Rhoads said. "An alternate solution is stream naturalization, which seeks to define a viable management goal for watersheds in landscapes characterized by intensive human modification."
The goal of naturalization is to establish "sustainable and stable fluvial systems capable of supporting healthy, biologically diverse aquatic ecosystems," said Edwin Herricks, a U. of I. professor of environmental engineering. "Previous attempts to naturalize streams, however, were largely trial-and-error approaches that drew upon limited knowledge in geomorphology and ecology."
To help expand that knowledge base, Herricks and his students recently developed an improved electrofishing technique that more closely relates fish species with stream habitats.
"Traditional electrofishing involves sampling fish populations with electrodes that move through a portion of a stream confined by nets," Herricks said. "Fish are stunned, netted for counting and released. But this technique disturbs the position of the fish, and is only effective for large volumes."
The new, fixed-electrode technique allows the researchers to sample fish from very small and well-defined aquatic habitat areas. By first characterizing specific habitat types on the basis of an extensive analysis of channel morphology, and then performing detailed fish counts, the researchers can draw general conclusions concerning the potential effectiveness of various approaches at stream naturalization.
"Results of this research will better define stream habitat and support improved management of fisheries in rivers and streams that drain agricultural landscapes," Herricks said.