Bucephalus polymorphus Baer, 1827 - a new fish parasite in Austria?

During parasitological studies of the invasive round goby fish species Apollonia melanostoma (Pallas, 1814) from the Danube River in 2007 the digenean Bucephalus polymorphus Baer, 1827 was detected for the first time in Austria. Encysted metacercariae of the parasite were found on the fins, skin and gills of the fish. The occurrence of the parasite is strictly dependant on the zebra mussel Dreissena polymorpha (Pallas, 1771), which acts as the obligatory first intermediate host in its life cycle. The mussel has also invaded Austrian waters, but has appeared in 1870 already. It will not be possible to establish whether the parasite was introduced to Austria with the gobies, or has arrived earlier, but it should be the subject of future investigations to ascertain whether the parasite will be able to establish a firm population in Austria, and whether this introduction puts additional pressure on the native fish populations.