Biodiversity & Conservation

For a full description of this biotope including characterizing species, distribution, survey information and references visit JNCC

This biotope occurs in the shallower reaches of the circalittoral (upper and lower) at depths of around 8 to 13 m with the main ascidian cover of Molgula manhattensis with some Polycarpa pomaria and a wide variety of other ascidians mixed in. Sponge species associated with this biotope include Tethya, Cliona, Stelligera rigida, Stelligera stuposa, Raspailia ramosa, Esperiopsis, Hemimycale and Dysidea. There are also several records with Axinella dissimilis and Axinella infundibuliformis. Nemertesia antennina occurs at most sites, also with Alcyonium digitatum and Actinothoe. Flustra is common in all these ascidian biotopes, but Chartella is only found in this one. Red algae associated with the upper circalittoral occur sporadically - more an artefact of the way in which the habitat records have been split. This biotope has some parallels with the erect sponge biotopes (e.g. MCR.ErSPbolSH), although it appears to be far siltier at most sites. (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

The main characteristic of this biotope is the dominance of rock by ascidians. However, the associated species are ones that are found in a wide range of biotopes.