Infection rates and prevalence of metazoan parasites of the non-native round goby (Neogobius melanostomus) in the Baltic Sea

Studies in the Baltic Sea have identified over 30 parasite taxa infecting the invasive round goby (Neogobius melanostomus (Pallas, 1814). In this study, we aimed at comparing parasite assemblages and infection rates (prevalence and intensity) in different populations across the invasive range in the Baltic Sea (Denmark, Lithuania, Estonia and Finland). Infection rates were 56-60% across all locations except Lithuania (28%). However, the parasite assemblages in the sampled populations were dissimilar, each location having unique parasites. In addition, many of the parasites were generalists commonly infecting native fish species. Based on the results of this study and those previously conducted in the Baltic Sea, the round goby has not retained parasites from its area of origin, but instead has been successively colonized by native generalist parasites. Although variable, overall parasite richness is still quite low around the Baltic compared to the native areas (34 vs 71 taxa, respectively). Also, prevalence and mean infection intensities in the Baltic Sea are significantly lower than in the native areas. Therefore, the invasion success of the round goby in the Baltic Sea can at least partly be attributed to enemy release, in this case shedding a significant proportion of their native parasite load.Peer reviewe

Environmental abundances of the non-native round goby Neogobius melanostomus influence feeding of native fish predators

The authors assessed the importance of the round goby Neogobius melanostomus as prey for three native predatory fish species, Atlantic cod Gadus morhua, European perch Perca fluviatilis and northern pike Esox lucius, in a northern and southern area of the Baltic Proper, using a combination of visual analysis and DNA metabarcoding of predator stomach contents. To explore the influence of environmental abundances of N. melanostomus on predation, they related the occurrence of N. melanostomus in predator diets to its abundance in survey fishing. Gadus morhua and E. lucius in the southern area showed the highest tendency to feed on N. melanostomus when it was abundant, as N. melanostomus occurred in up to 100% of stomachs and constituted up to 88% of the total diet volume proportion. The diet contribution of N. melanostomus was associated with N. melanostomus abundances for G. morhua and E. lucius, and when N. melanostomus was abundant, these predators exhibited lower prey richness and a higher degree of piscivory. G. morhua and P. fluviatilis also fed less on crustacean prey when N. melanostomus was abundant. The high importance of N. melanostomus in diets of native fish predators may modify indirect interactions between N. melanostomus and native prey species in invaded coastal communities

A laboratory study of potential effects of the invasive round goby on nearshore fauna of the Baltic Sea

In the Baltic Sea, species diversity is relatively low and the introduction of new predator species can have large direct and indirect impacts on native species - both prey and potential competitors. The alien round goby Neogobius melanostomus Pallas, 1811 was introduced to the Baltic Sea in the early 1990s and is now well-established. We examined the feeding habits of male round gobies from the Aland Islands, Finland, where round gobies were first recorded in 2011. Specifically, we tested whether small round gobies (Peer reviewe

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Environmental abundances of the non-native round goby Neogobius melanostomus influence feeding of native fish predators

The authors assessed the importance of the round goby Neogobius melanostomus as prey for three native predatory fish species, Atlantic cod Gadus morhua, European perch Perca fluviatilis and northern pike Esox lucius, in a northern and southern area of the Baltic Proper, using a combination of visual analysis and DNA metabarcoding of predator stomach contents. To explore the influence of environmental abundances of N. melanostomus on predation, they related the occurrence of N. melanostomus in predator diets to its abundance in survey fishing. Gadus morhua and E. lucius in the southern area showed the highest tendency to feed on N. melanostomus when it was abundant, as N. melanostomus occurred in up to 100% of stomachs and constituted up to 88% of the total diet volume proportion. The diet contribution of N. melanostomus was associated with N. melanostomus abundances for G. morhua and E. lucius, and when N. melanostomus was abundant, these predators exhibited lower prey richness and a higher degree of piscivory. G. morhua and P. fluviatilis also fed less on crustacean prey when N. melanostomus was abundant. The high importance of N. melanostomus in diets of native fish predators may modify indirect interactions between N. melanostomus and native prey species in invaded coastal communities