Functional interactions of non-native aquatic fauna with European freshwater bivalves: implications for management

Freshwater bivalves are key faunal elements of aquatic ecosystems. Native species declines are paralleled by increasing distribution and abundances of non-native species. Appropriate management of both groups depends on knowledge of their interactions, which remains limited. Herein, we systematically review the current knowledge status of native and non-native bivalves in Europe, analyzing their functional interactions as well as niche and distribution overlaps between species. We also review existing management tools for non-native species in light of their applicability and sustainability. Strong and multiple interactions as well as niche overlaps between native and non-native bivalves already exist in Central Europe, especially with regard to Dreissena spp., Corbicula spp., and Sinanodonta woodiana. Direct competition is low with native species that have a high degree of specialization such as Margaritifera margaritifera, whereas the greatest niche overlap and competition occurs in generalist species such as Anadonta anatina, Unio pictorum, and S. woodiana. Early detection and preventive measures against undesired species are most successful in limiting their spread. Most methods for managing non-native species are unspecific and thus also include undesired side effects on endangered native species. The conservation and restoration of functionally intact bivalve habitats are the most sustainable and most resilient ways of management.