Justin R. Smerud John Tix Susan M. Schleis Kim T. Fredricks Richard A. Erickson Jon Amberg William S. Morrow Carolyn M. Koebel Elizabeth A. Murphy Chad Vishy K. Douglas Blodgett Aaron R. Cupp 2018 <p><span>Construction of a water management structure (WMS) in the levee surrounding The Nature Conservancy’s Emiquon Preserve (Havana, Illinois, USA) created a new hydrological connection and potential aquatic invasive species pathway between the Illinois River and a large conservation wetland complex. Site managers need a control tool that deters the upstream passage of non-native fishes into the wetland lakes, but does not interfere with normal gate operation and water discharge. This short field study evaluated carbon dioxide (CO</span>_{<span class="style1">2</span>}<span>) injected into water as a non-obstructive method to reduce fish abundance near the WMS culverts. We quantified relative fish abundance using underwater sonar with and without injection of CO</span>_{<span class="style1">2</span>}<span>&nbsp;into culverts during three discharge events: no flow (0 m</span>^{<span class="style1">3</span>}<span>/s), restricted flow (0.9 m</span>^{<span class="style1">3</span>}<span>/s), and unrestricted flow (3.2 m</span>^{<span class="style1">3</span>}<span>/s). Overall, CO</span>_{<span class="style1">2</span>}<span>&nbsp;reached or exceeded our target concentration of 100 mg/L during no flow and restricted flow, and fish abundance was 70–95% lower at culvert entrances relative to untreated control days. The target CO</span>_{<span class="style1">2</span>}<span>&nbsp;level was not reached during unrestricted flow and fish abundance was not reduced during CO</span>_{<span class="style1">2</span>}<span>&nbsp;injection. Atmospheric CO</span>_{<span class="style1">2</span>}<span>&nbsp;concentrations were inconsequential and unaffected by CO</span>_{<span class="style1">2</span>}<span>&nbsp;treatments throughout testing. Results from this initial field study provide several considerations for CO</span>_{<span class="style1">2</span>}<span>&nbsp;as a fish deterrent in natural environments.</span></p> application/pdf 10.3391/mbi.2018.9.3.12 en REABIC Field evaluation of carbon dioxide as a fish deterrent at a water management structure along the Illinois River article