Factors influencing round goby use of northern Lake Michigan coastal wetlands

            Round goby (Apollonia melanostomus) populations in the Great Lakes have the potential to disrupt invertebrate and fish community dynamics by invading coastal wetlands.  The extent and factors influencing round goby use of wetland habitats has not been fully examined.  We investigated the variation of round goby abundance in exposed coastal wetlands and adjacent habitats in the Beaver Archipelago of northern Lake Michigan and related abundance to biotic and abiotic variables.  Round goby abundance (trapnet catch and video transects) did not differ between open water and exposed wetland sites.  Multivariate ordinations of the fish and macroinvertebrate communities and abiotic habitat variables revealed environmental gradients that were correlated to round goby abundance.  Abundance was found to be greatest where nitrate-nitrogen, oxidation-reduction potential, and dissolved oxygen were high and lowest where alkalinity, total dissolved solids, and temperature were high.  Round goby abundance was also related to a macroinvertebrate gradient and was highest where Ephemeroptera were plentiful and lowest where the macroinvertebrate community was dominated by amphipods.  It appears that round goby abundance is highest in the most productive areas of these mesotrophic/oligotrophic systems regardless of habitat type (wetland vs. open water) in the Beaver Archipelago of northern Lake Michigan.