Recent observations of the introduced Fenestrulia delicia winston, Hayward & Craig, 2000 (Bryzoa) in Western Europe

We detail the discovery of recently established immigrant populations and beached material of the encrusting bryozoan Fenestrulina delicia from the Atlantic coasts of Europe. This species of unknown origin is highly invasive and, in contrast to most other introduced bryozoans spreads along offshore natural and artificial hard substrates, rather than hopping from one marina to another. Part of the material, collected in situ, was found on empty shells at locations well known for their aquaculture of oysters and mussels. This suggests that the import of shellfish could be the vector of primary introduction. Beached material suggests that floating plastic debris might be a vector of transport for secondary introduction. The base of offshore wind turbines forms a supplementary substrate in the sandy southern North Sea and probably provides stepping stones for this exotic species.