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  4. MB1-212 - Forêt de Alaria esculenta avec anémones denses et éponges encroûtantes sur roche en place extrêmement exposée de l'infralittoral en Atlantique
  5. Description
MB1-212 - Forêt de Alaria esculenta avec anémones denses et éponges encroûtantes sur roche en place extrêmement exposée de l'infralittoral en Atlantique

Alaria esculenta forest with dense anemones and crustose sponges on extremely exposed Atlantic infralittoral bedrock
MB1-211 - Alaria esculenta sur roche en place exposée de la frange infralittorale inférieure en Atlantique
MB1-213 - Forêt de Laminaria hyperborea à tapis faunistique (éponges et polyclinides) et algues rouges foliacées sur roche très exposée de l'infralittoral en Atlantique

Classification des habitats EUNIS 2022

Descriptif de l'habitat

This biotope has only been recorded from Rockall, where Alaria esculenta appears to replace Laminaria hyperborea as the dominant kelp forest species on the extremely wave-exposed steep and vertical rock, a zone that extends from 14 m down to 35 m. Beneath the A. esculenta canopy, the rock surface is covered by a dense turf of anthozoans such as Sagartia elegans, Phellia gausapata and Corynactis viridis, encrusting sponges and coralline algae. The gastropod Margarites helicinus can be found grazing on the kelp fronds, whereas the crab Cancer pagurus can be found among the kelp stipes. The bryozoan Tubularia indivisa also occur, but it does not form such a dense turf as in more shallow waters, while the ascidian Botryllus leachi is found encrusting the large brown seaweeds. Cryptopleura ramosa is the dominant red seaweed on horizontal surfaces. The kelp Laminaria digitata is reported to occur mixed with A. esculenta on the nearby Helen's reef.
Situation: Above the zone with MB1-212 (about 5 m to 13 m) A. esculenta still dominates, but it resembles more closely the typical sublittoral fringe A. esculenta biotope (unit MB1-2111), though it has a very dense turf of small hydroids and few foliose algae. Towards the lower part of this A. esculenta forest (30 m to 35 m), the density of A. esculenta is reduced and the rock surface is characterised by a dense turf of red algae (unit MB1-221).

Bibliography

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