PARENT SESSION
Tuesday, August 8, 8:00-11:30 am
COS 27 - Aquatic ecology II: river ecosystems, Part II
L-14, Lobby Level, Cook Convention Center
Presiders: T Barnwell

Changes in backwater lake habitat reflected in the diet of common carp (Cyprinus carpio) from Swan Lake, Calhoun County, Illinois.

Timmermann, Thomas^{*,1, 2}, Dolan, Chad¹, Chick, John¹, ¹ Illinois Natural History Survey, Champaign, IL² University of Illinois, Champaign, IL

ABSTRACT- Backwater lakes are critical components of large river ecosystems providing nursery, refuge and feeding grounds for many fishes. Due to recent alterations in the hydrology of large river systems, many of these backwaters have been degraded, filling in with sediment and losing large amounts of aquatic vegetation. In Swan Lake, there have been significant alterations made to the lake to combat the sedimentation and loss of vegetation. Major alterations include construction of a levee, dividing the lake into units, allowing for different backwater lake management strategies to be implemented in the different units. Since implementation of these management strategies, we have noticed a difference in the diets of Common Carp (Cyprinus carpio) between the units. One unit had 25% empty stomachs and the other 66% empty. While the overall prey selection did not vary significantly, the amount of food consumed did. We believe that sediment flocculency might be the main cause of changes in diets. Sediment cores are being taken to determine if higher flocculency causes a decrease in the amount of food consumed.

Key words: large river backwaters, diet, Cyprinus carpio