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Tuesday, January 30 • 10:20am - 10:40am
RIVERS & OXBOWS: Fish Community Composition at the Emiquon Nature Preserve Water Management Structure

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AUTHORS. Andrya L. Whitten, Olivea M. Mendenhall; Andrew F. Casper – Illinois Natural History Survey

ABSTRACT. Water management structures (WMS) are commonly used to regulate water levels in restored backwaters of large rivers. The costs and benefits of these structures to the surrounding ecosystem can vary depending on their design and location. Understanding how native and nonnative fishes use (e.g., longitudinal movements and opportunistic feeding) such structures is essential to restoration activities. The Emiquon Nature Preserve in Lewiston, IL is a 6700-acre restored floodplain lake that uses a WMS to control water levels. In 2017, we evaluated fish community composition and environmental conditions on both sides (i.e., Emiquon and the Illinois River) of the WMS when it was non-operational and operational (i.e., flowing into the Illinois River). Fish community and water quality sampling followed the Upper Mississippi River Restoration Program – Long Term Resource Monitoring protocols. In total, we captured 886 fish comprising 14 species in Emiquon and 1431 fish comprising 25 species in the Illinois River. The NMDS analysis indicated that the fish community composition differed when the WMS was operational versus non-operational. Results from the SIMPER analysis showed that increased catches of white bass, threadfin shad, and skipjack herring are driving the differences in the Illinois River when the WMS is operational while high catches of gizzard shad are the main contributors to differences when the WMS is non-operational. In Emiquon, increased catches of bluegill when the WMS is operational and variability in largemouth bass and gizzard shad catches contribute to the differences in the fish community. Changes in environmental conditions are likely causing the shift in the fish community composition. When the WCS is operational, the flow of water from Emiquon into the Illinois River changes the surrounding fish habitat by providing a microhabitat of increased flow and highly productive water that likely contains increased food resources.

Tuesday January 30, 2018 10:20am - 10:40am
103E

Attendees (1)