Summer microhabitat use and overlap by the invasive Round Goby (Neogobius melanostomus) and native darters in the Trent River (Ontario, Canada)

Abstract

Understanding the impacts of the invasive Round Goby (Neogobius melanostomus) is important for North American native fish conservation. One proposed mechanism for native species declines is competition for habitat. In this study, summer habitat use by Round Goby and Channel Darter (Percina copelandi) and Logperch (P. caprodes) was studied in the Trent River (Canada). Spot-electrofishing and systematic habitat sampling were used to measure habitat availability and use. Suitability for all species varied across the range of habitat conditions. At Glen Ross, habitat suitability for Channel Darter and Round Goby was highest at intermediate water depths (0.2-0.6 m), lowest at high water velocities (> 1.0 ms-1) and increased with greater amounts of gravel and cobble. There were no significance habitat differences between capture locations of the two species. At Meyer's Reach, Logperch and Round Goby habitat suitability was highest at intermediate water depths (0.4-0.6 m) and where gravel and cobble were abundant. The relationship between suitability and water velocity differed between species, with moderate velocities less suitable for Round Goby. The amount of boulder and bedrock at capture locations of each species differed. Results indicate that competition for habitat with Round Goby will vary among darter species.