Northern range expansion of the Asian mussel Arcuatula senhousia (Benson, 1842) along the French Atlantic coasts

The Asian mussel Arcuatula senhousia is known as a successful invader into coastal and estuarine environments worldwide. We here report its Northward expansion along the French Atlantic coast evidenced by new records from the commercial ports of La Rochelle (Bay of Biscay) and Dunkirk (North Sea), both in 2018, following sampling of benthic macroinvertebrates. To date, the Asian mussel has only been observed along the French coast from the Mediterranean Sea and the Southern part of the Bay of Biscay. Its presence in these new locations, which are important for international maritime transport, is most likely related to ship ballast water and/or sediment as vector of introduction. These new insights suggest that this species has not yet finished its expansion process, which could be at the origin of irreversible impacts on ecosystem structure, functioning and services.