Alien Sinanodonta woodiana (Lea, 1834) and protected Anodonta cygnea (Linnaeus, 1758) (Bivalvia: Unionidae) in the Spytkowice pond complex

Dead individuals of Chinese mussel Sinanodonta woodiana (Lea) were found in 2009 in the complex of fishponds in Spytkowice (S. Poland) in the Vistula River valley. Earlier records of this invasive alien species in Poland come mostly from heated waters. Its occurrence in fishponds indicates that it tolerates also colder waters; many aquatic ecosystems in Poland may be threatened with its invasion. Endangered swan mussel Anodonta cygnea (Linnaues) was found in the same fishponds. The species had not been reported from this area before and it is uncertain whether persistence of its population here is threatened by the invasion of Chinese mussel.