Distribution and potential impacts of non-native Chinese pond mussels Sinanodonta woodiana (Lea, 1834) in Bavaria, Germany

The Chinese pond mussel, Sinanodonta woodiana , is non-native to European freshwater systems. Originating from Asia, it was brought to Europe in the 1970s and is now spreading across many countries. Management of the species is currently limited by a lack of information on the actual distribution and population characterisation of S. woodiana as well as on the co-occurrence of native mussels potentially resulting in competition. For this paper, we examined nine water systems in the German federal state of Bavaria with randomly observed and anecdotally reported S. woodiana occurrences. We recorded the density and biomass of S. woodiana and of the co-existing mussel species as well as the habitat characteristics. We found S. woodiana in eight water systems, co-existing with other native and invasive mussel species in seven of them. The distribution of S. woodiana was geographically widespread throughout Bavaria, indicating great invasion potential. In one fish pond, S. woodiana was the only mussel species occurring with the highest mean biomass (1286.0 ± 1067.7 g m −2 ) and with the biggest specimen (25.0 cm and 1616.0 g). The wide range of habitat variables matched the expectation of a wide ecological niche for the species. This study provides evidence that S. woodiana has already become established in many water systems in Bavaria, with fish ponds and fisheries management practises being a likely vector. To counteract this species and to conserve native mussel species, it is important to implement effective legislation, to take measures to eradicate this invasive mussel transnationally, and to raise public awareness.