The Nature Conservancy's Emiquon Preserve: The emerging food web in a newly restored floodplain lake

Two backwater lakes along the Illinois River, Thompson and Flag lakes, were historically known as two of the most productive backwater lakes of the Illinois River.  In the early 1920’s, Thompson and Flag lakes were leveed from the Illinois River, drained, and farmed.  The area has recently been reclaimed by The Nature Conservancy.  We collected stomach contents from largemouth bass Micropterus salmoides on a bi-weekly basis April – October, 2008 in order to determine the emerging food web at the Emiquon Preserve.   A shift in diet contents from less profitable prey items (cladocerans, benthic invertebrates) to higher profitable prey items (fish) was observed in mid-July, 2008 as seen in community analysis and Index of Relative Importance (IRI) values for each prey group.  Additionally, diet breadth (B) of largemouth bass significantly decreased over time (p = 0.034, r² = 0.266).  These observations may correspond to the fish management goal of maintaining bass at a hungry state at the appropriate time to inhibit the potential recruitment of invasive fish species in the early stages of the restoration process.  Continued diet analysis will provide information regarding management implications for the fish community at Thompson Lake and for future floodplain lake restoration efforts.