Does Disturbance Facilitate Round Goby Invasion?

Disturbance can leave ecosystems in vulnerable states, increasing opportunity for nonnative species to colonize (invasibility). We tested this hypothesis by conducting assessments of habitat, water quality, and fish and macroinvertebrate communities across a disturbance gradient in several rivers in Michigan to determine the factors associated with invasibility of round goby (Neogobius melanostomus). Factors affecting site condition were addressed at multiple spatial scales, first with land cover at the watershed scale, followed by a fine-scale geographic assessment of macroinvertebrate data provided by watershed monitoring groups. Land cover type was not significantly correlated with round goby density at this broad scale. However, with finer-scale watershed monitoring data, sites with greater disturbance had higher than expected abundances of round goby. Finally, divergent fish community composition was observed between low and high quality sites, indicating either antagonistic interactions between native fishes and round goby or simply reflecting environmental differences among those sites. More data will need to be collected to determine the specific impacts of interactions between round goby and native competitors. The results of this study may aid our understanding of factors that constrain or promote goby invasion, and may be applied in other systems or to the spread of other invasive species.