ROUND GOBY INVASION AND THE IMPACT ON NATIVE STREAM FISH ASSEMBLAGES
Nonnative species can have a variety of impacts on newly invaded areas. We tested the hypothesis that round goby (Neogobius melanostomus) invasion is associated with decreased diversity of native competitors across a spatial gradient from the site to watershed scale. Fish surveys were conducted at three sites in each of five Michigan streams over two years. Fish community diversity did not change at the site or watershed level over time. Species aggregation was observed at site and watershed levels indicating potential interaction with habitat availability. Native species likely to compete with round goby (i.e. darters) were lower in abundance (p=0.005) where goby were most abundant. Similarly, goby abundance was greater (p=0.020) at sites with lower diversity in 2015 but not 2016. This suggests some inter-annual variation in goby abundance, potentially related to boom and bust cycles along the invasion front. However, in established populations goby had diet preference for the most abundant invertebrates which may be imposing long-term competitive stress for food resources on native fishes. With further analysis, we hope to identify causal factors constraining or promoting goby invasion.
Corey Krabbenhoft (Primary Presenter/Author), Wayne State University, email@example.com;
Donna Kashian ( Co-Presenter/Co-Author), Wayne State University, firstname.lastname@example.org;