Feeding of the Alien Round Goby Neogobius melanostomus (Perciformes: Gobiidae) in the Southeastern Baltic

The feeding of the Ponto-Caspian alien round goby Neogobius melanostomus in the coastal zone of the Baltic Sea near the Curonian Spit, in the Vistula Lagoon, and in the eastern part of Gdansk Bay has been studied. The round goby in coastal waters prefers biotopes with various shelters: boulders, large pebbles, etc. In the diet of the round goby, there is a significant proportion of fouling organisms inhabiting these objects. If fouling organisms are absent for some reason, the goby switches to other types of prey: mollusks, free-living crustaceans, insect larvae, and other groups of benthic and nektobenthic organisms. There is a connection between the food spectrum and the size of the round goby: large individuals consume larger prey. The round goby implements a food strategy which consists in the fact that all available organisms (both in size and territorially) are used for food. Such food plasticity is one of the reasons for the wide expansion of this species outside the native range.