The invasive Asian clam Corbicula fluminea in Polish rivers: the importance of thermal discharge from power plants for its spread.

So far in Poland, the Asian clam Corbicula fluminea has been reported from the Oder (Odra) and Vistula River. Its new population has been discovered in the Warta-Gop?o Canal in Konin (central Poland), where water temperature can reach 34°C, as the canal is a part of a power plant lake cooling system. The spatial distribution of C. fluminea was found to be very uneven and that is probably why this species was not found during earlier research. The highest density of C. fluminea was 78 ind.·m-2 at the site where water flow was the fastest (2.49 m·s-1), providing sufficient oxygenation of the water. The results suggest that existing information about the distribution of C. fluminea may be far from complete because the clam can be present also in the habitats that were not regarded as suitable for the species according to earlier reports, and therefore have not been monitored for its presence.