The status of the Duck Mussel, Anodonta anatina (Linnaeus, 1758), in Lough Derg, Shannon River, following the arrival of three invasive bivalves

The Zebra Mussel, Dreissena polymorpha, was introduced to Lough Derg, in the Shannon catchment, Ireland, during the early 1990s. Its presence led to the decline of the native Duck Mussel, Anodonta anatina, its empty shells remaining at lake depths to 11 m. Dreissena polymorpha shells were recovered throughout the lake to depths over 30 m. The Asian Clam, Corbicula fluminea, was first recorded in Lough Derg in 2011 and has also extended its range beyond 30 m, although it was not found in the most southern region of the lake. The Quagga Mussel, Dreissena bugensis, first found in 2021, has locally displaced D. polymorpha. Exposed shells of all these species provide a settlement surface for byssal attachment and a change to sediment habitats, with their shells likely to provide refuges for other invertebrates.