Description of [Alcyonium digitatum] and [Metridium senile] on moderately wave-exposed circalittoral artificial substrata
This biotope is found on moderately wave-exposed circalittoral steel wrecks that are subject to moderately strong to weak tidal streams. The vertical and upward facing sides of the wreck stand proud of the seabed, and may be colonised by dense aggregations of Alcyonium digitatum, Metridium senile and Actinothoe sphyrodeta. Caryophyllia smithii and Corynactis viridis are also recorded with varying abundance. A mixed faunal turf may also be present on the vertical sides, with Nemertesia antennina, Flustra foliacea and Bugula plumosa. Where tidal stream strength is elevated, for example if the wreck is situated in a straight or sound, the hydroid Tubularia indivisa may prevail. Crustaceans such as the crabs Necora puber, Maja squinado and Cancer pagurus, the lobster Homarus gammarus and barnacles are all recorded. The top shell Calliostoma zizyphinum is also recorded.