Impact of round goby on native invertebrate communities - an experimental field study

This experimental field study provides first insights into the impact of a widely spread non-native fish species, round goby Neogobius melanostomus (Pallas 1814), on the diversity of native epifaunal macroinvertebrate communities in the Baltic Sea. A cage experiment was conducted in a macrophyte habitat in the Åland islands located in the northern Baltic Sea. Round gobies (13.5 ± 0.8 cm) affected macroinvertebrate biodiversity from a taxonomic and a trait-based point of view. Specifically, round goby decreased overall abundance, biomass and taxon richness of epifaunal invertebrates. Additionally, taxonomic and trait-based composition were affected, as the gobies reduced abundances of common bivalve (Cerastoderma spp. and Mytilus sp.) and gastropod species (Hydrobia spp.), and thereby modified the relative trait composition of the invertebrate assemblages. Round gobies consumed mainly larger epifaunal individuals leading to an overall decrease in invertebrate body size. Such alterations in taxonomic and trait-based diversity and composition of invertebrate communities through round goby predation may have implications for native fish species and other trophic levels in the respective food webs through food competition and trophic cascades. Round gobies might therefore affect ecosystem processes in invaded areas, and thus influence ecosystem functioning and services.