Description of [Corynactis viridis] and a mixed turf of crisiids, [Bugula], [Scrupocellaria], and [Cellaria] on moderately tide-swept exposed circalittoral rock
This biotope typically occurs on wave-exposed, vertical or steep, circalittoral bedrock or large boulders, usually subject to moderate or strong tidal streams. It is characterised by dense aggregations of the anemone Corynactis viridis and the cup coral Caryophyllia smithii intermixed with a short bryozoan turf of one or more Crisia spp., Scrupocellaria spp., Bugula spp. and Cellaria spp. Occasionally, this turf obscures the underlying C. virdis and C. smithii. Cushion and encrusting sponges, particularly Pachymatisma johnstonia, Cliona celata, Esperiopsis fucorum and Dysidea fragilis, are present in moderate amounts at many sites. The axinellid sponges Stelligera spp. and Raspailia spp. are less frequently recorded. Clumps of large hydroids such as Nemertesia antennina and Nemertesia ramosa as well as the soft coral Alcyonium digitatum and the bryozoan Alcyonidium diaphanum may be found covering the hard substratum. The anemones Actinothoe sphyrodeta and Sagartia elegans are typically present in low numbers, while the hard `coral' Pentapora foliacea is also occasionally observed. The most frequently recorded echinoderms are Marthasterias glacialis and Asterias rubens, although other species such as Echinus esculentus may also be seen. The rocky substratum may have a patchy covering of encrusting red seaweeds/algae. The crabs Necora puber and Cancer pagurus may be seen in crevices or under overhangs. This biotope is regularly recorded around south west England and Wales, often on vertical rock faces. Situation: Due to its wave-exposed nature, kelp park and forest biotopes (units A3.115 and A3.111) are commonly found in the infralittoral zone shallower than this biotope, and feature species such as Laminaria hyperborea, Sacchoriza polyschides and Alaria esculenta.