Competitive interactions between invasive round goby and native white sucker in streams

Abstract

The secondary invasion of the round goby ( Neogobius melanostomus) into tributaries of the Laurentian Great Lakes has resulted in ecological impacts on many native benthic species. However, the ecological impacts on white sucker ( Catostomus commersonii), a native benthic species has not been examined. A comparative control and invaded site study design was used to examine diet overlap and the dietary impact of the round goby invasion on white sucker’s trophic niche. We found significant diet overlap between round goby and white sucker, and white sucker in sympatry with round goby shift their feeding strategy to be more generalist when compared to white sucker in uninvaded locations. No influence of diet competition with round goby on the trophic niche of white sucker was found in this study. Our results support the hypothesis that white sucker are experiencing competition for prey items with round goby. These increased competitive interactions may exacerbate the observed declines in white sucker abundance as round goby continue their invasion upstream in Lake Ontario tributaries.