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  4. MC1-233 - Antedon spp., ascidies solitaires et fins hydraires sur roche du circalittoral abritée en Atlantique
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MC1-233 - Antedon spp., ascidies solitaires et fins hydraires sur roche du circalittoral abritée en Atlantique

Antedon spp., solitary ascidians and fine hydroids on sheltered Atlantic circalittoral rock
MC1-232 - Grandes ascidies solitaires et éponges dressées sur roche du circalittoral abritée en Atlantique
MC1-234 - Novocrania anomala et Protanthea simplex sur roche du circalittoral abritée en Atlantique

Classification des habitats EUNIS 2022

Descriptif de l'habitat

This biotope is typically found on silty boulder or rock slopes, in the sheltered parts of sealochs, subject to weak or very weak tidal currents. The seabed consists of smooth, silty bedrock or boulders, often as outcrops on mixed muddy sediment. There are often small vertical faces on the sides of rock ridges, and at few sites, there may be more extensive steep or vertical bedrock. In sharp contrast to the barren, grazed appearance of MC1-2311, the species composition of unit MC1-233 is quite diverse, although no one phyla dominates. A wide range of encrusting species may be found, including the brachiopod Neocrania anomala, the saddle oyster Pododesmus patelliformis, encrusting red algae and polychaetes (Pomatoceros triqueter and Protula tubularia). Other conspicuous species include crinoids on the tops of boulders (Antedon bifida, commoner in shallower water and Antedon petasus, commoner in deeper water), scattered solitary and colonial ascidians (Ascidia mentula, Ascidia virginea, Corella parallelogramma, Clavelina lepadiformis and Ciona intestinalis) and tufts of fine hydroids (Kirchenpaueria pinnata, Nemertesia antennina, Obelia dichotoma and Halceum halecinum). The cup coral Caryophyllia smithii and the crustose bryozoan Parasmittina trispinosa are all typically present, as are a wide range of echinoderms, including the sea urchin Echinus esculentus, the starfish Asterias rubens and Crossaster papposus, and the brittlestars Ophiothrix fragilis and Ophiura albida. Other species recorded are the squat lobster Munida rugosa, the hermit crab Pagurus bernhardus and the chiton Tonicella marmorea.
Situation: The range of biotopes shallower and deeper than MC1-233 is typical of a sheltered sealoch. Silted kelp biotopes (e.g. units MB1-239, MB1-23A) are typically found shallower than MC1-233 in the infralittoral zone. Deeper than MC1-233, the boulder slope typically grades into a muddy slope or plain (units A5.3 or A5.4), along with fauna commonly associated with soft-sediments (e.g. seapens and the mud snail Turritella).

Bibliography

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