by round gobies include the Aegean Sea, different parts of the Baltic Sea, the North Sea basin, and the Danube and Rhine basins. In the German part of the Baltic Sea this fish was first noted near Rügen Island. It is now distributed all along the southwestern Baltic Sea coast, including Stettiner Haff (Szczecin Lagoon), the Unterwarnow (Warnow river estuary), the mouth of the Trave, and the Nord-Ostsee (Kiel) Canal. As of 2010, the westernmost site of round goby occurrence in Europe was the lower Scheldt, including the tidal zone in the river mouth, and Albert Canal, Belgium. In 2011, the round goby began invading the fresh waters of France; the species appeared in the Rhine River (on the border between France and Germany) and in the French part of the Moselle River. Parasites In total, fifty-two parasite species are registered in the round goby in its native area. The most abundant parasites of the Black Sea round goby are metacercariae of trematodes of the Heterophyidae family, such as Cryptocotyle concavum, C. lingua, and Pygidiopsis genata. The trematodes C. lingua and P. genata can infest humans. In the 1950s, along the coast of the Gulf of Taganrog (Sea of Azov), the round goby was registered as a host of epizootic nematodes Tetrameres fissispina and Streptocara crassicauda, which were fatal to ducklings. In the Gulf of Gdańsk, Baltic Sea, the parasites of the invasive round goby consist of twelve species. The core of the parasite fauna comprises two species of trematode metacercariae: C. concavum and Diplostomum spathaceum. Also in the Baltic Sea, the round goby is a paratenic host of the invasive nematode Anguillicoloides crassus. In the Vistula Lagoon, the most abundant parasites of the round goby are nematodes Hysterothylacium aduncum and Anguillicoloides crassus. Twenty-five species of parasites are noted in the round goby in the American Great Lakes. The trematode D. spathaceum is the most abundant core species overall, while the cestode Proteocephalus sp. and the trematode Neochasmus umbellus are also well represented. The round goby may prevent some of the metacercariae of N. umbellus from completing their life cycle. The parasite "load" on the invasive gobies in the Great Lakes appears relatively low in comparison with their native habitats, lending support to the "enemy release hypothesis". References External links Round Goby, an invasive species in the Great Lakes Aquatic Invasive Species-Minnesota Sea Grant Global Invasive Species Database Harmful Aquatic