MC1-2161 - Polyclinum aurantium et Flustra foliacea sur roche du circalittoral abrasée par le sable, soumise aux courants de marée et modérément exposée aux vagues en Atlantique (EUNIS 2022)

MC1-2161 - Polyclinum aurantium et Flustra foliacea sur roche du circalittoral abrasée par le sable, soumise aux courants de marée et modérément exposée aux vagues en Atlantique

Polyclinum aurantium and Flustra foliacea on sand-scoured tide-swept moderately wave-exposed Atlantic circalittoral rock

MC1-2162 - Flustra foliacea, petites ascidies solitaires et coloniales sur roche ou blocs du circalittoral soumis aux courants de marée en Atlantique

Classification des habitats EUNIS 2022

Descriptif de l'habitat

This variant is typically found on the upper face of moderately exposed, moderately tide-swept, circalittoral bedrock or boulders. Sand and silt are periodically re-suspended in the water column, resulting in scour-tolerant species being characteristic of these areas. There is a dense covering of the scour-resistant bryozoan Flustra foliacea attached to the bedrock plains and boulders. The colonial ascidian Polyclinum aurantium commonly covers the rock surface at most locations within this biotope - itself incorporating sand grains into its surface to give it the appearance of sandy rock nodules. Other ascidians that may occur in this crust are the flat, encrusting colonial Botrylloides leachi, Botryllus schlosseri and the colonial ascidian Clavelina lepadiformis, although in varying quantities at each location. A short turf of other bryozoans such as Alcyonidium diaphanum, Bugula plumosa and Bugula flabellata occur amongst the ascidians. Other species found in this biotope are the sponges Cliona celata, Leucosolenia botryoides and Scypha ciliata, the hydroids Tubularia indivisa, Nemertesia antennina, Halecium halecinum and the anthozoans Alcyonium digitatum and Urticina felina. Echinoderms which may be present include the starfish Asterias rubens, Crossaster papposus and the brittlestar Ophiothrix fragilis. Crustaceans such as the crab Cancer pagurus, the hermit crab Pagurus bernhardus and the lobster Homarus gammarus may be observed in crevices and under boulders. The palps of the polychaete Polydora spp. may be observed whilst the nudibranch Janolus cristatus may be seen preying on the hydroid/bryozoan turf. This variant is commonly found on the Northumberland coast, Flamborough Head and the Lleyn Peninsula.
Situation: As MC1-2161 tends to occur in waters with a sediment load, the resulting light penetration is reduced, meaning that kelp forests such as unit MB1-21A, normally found shallower than MC1-2161 in the infralittoral zone, are present over a narrower depth range.

Bibliographie

European Topic Centre on Biological Diversity 2022. EUNIS marine habitat classification 2022 including crosswalks. Table Excel. (Source)