Colonization of the round goby, Neogobius melanostomus (Gobiidae) by parasites in the new environment of the Gulf of Gdańsk (Southern Baltic).

The round goby (Neogobius melanostomus) is a non-indigenous species in the Baltic Sea, introduced to its waters (the Gulf of Gdańsk) from the Black, Azov, and Caspian Seas. For this reason, an attempt was made to determine the species' parasitic fauna in its new environment. Within 1994-2000, a total of 201 round goby specimens caught in the Gulf of Gdańsk were examined. The parasites found represented protozoans (Trichodina domerguei domerguei), digeneans (Diplostomum spp. metacercariae), cestodes (Bothriocephalus scorpii, plerocercoids), nematodes (Hysterothylacium aduncum L3, L4, and adults), and acanthocephalans (Echinorhynchus gadi and Pomphorhynchus laevis). The parasitic species found are common in the Gulf of Gdańsk. It should be emphasized that, since the round goby has only recently appeared in the Gulf, the parasitic fauna of this fish is not yet complete.