2. Data & tools
  3. Search habitat
  4. MC1-2243 - Alcyonium digitatum avec Securiflustra securifrons sur roche du circalittoral soumise aux courants de marée et modérément exposée aux vagues en Atlantique
  5. Description
MC1-2243 - Alcyonium digitatum avec Securiflustra securifrons sur roche du circalittoral soumise aux courants de marée et modérément exposée aux vagues en Atlantique

Alcyonium digitatum with Securiflustra securifrons on tide-swept moderately wave-exposed Atlantic circalittoral rock
MC1-2242 - Alcyonium digitatum, Spirobranchus triqueter (anciennement Pomatoceros triqueter), algues et bryozoaires encroûtants sur roche du circalittoral exposée aux vagues
MC1-2244 - Ophiures sur faune et flore encroûtantes de la roche du circalittoral exposée à modérément exposée aux vagues en Atlantique

Classification des habitats EUNIS 2022

Descriptif de l'habitat

This variant is typically found on the upper and vertical faces of moderately wave-exposed circalittoral bedrock subject to moderately strong to weak tidal streams. The rock surface is dominated by Alcyonium digitatum and the bryozoan Securiflustra securifrons. The rock between these species appears fairly sparse and grazed, with expanses of encrusting red algae. The sea urchin Echinus esculentus is frequently seen, and in collaboration with the light attenuating effects of depth, is probably the principal reason for the lack of algal turf. Other species found include the hydroids Abietinaria abietina, Nemertesia antennina, Thuiaria thuja, the bryozoans Cellepora pumicosa, Parasmittina trispinosa, Flustra foliacea, Alcyonidium diaphanum and other bryozoan crusts. Encrusting species such as the polychaete Pomatoceros triqueter and the barnacle Balanus balanus are frequently observed. Other species present include Asterias rubens, Antedon bifida, Ophiura albida, Ophiothrix fragilis, Caryophyllia smithii, Urticina felina, Clavelina lepadiformis, Calliostoma zizphinium and Pandalus montagui.
Situation: Above this biotope, you tend to find exposed kelp forest and park (unit MB1-213). There is a tendency for slight scouring to occur in this biotope. However, if this scour increases further, for example if water movement increases, mobilising more sand, this biotope may graduate into MC1-223. In more silty sites, there is a tendency for S. securifrons to be replaced by F. foliacea as the dominant bryozoan, turning the biotope into MC1-2241.
Temporal variation: Whilst the great majority of species in this variant are most likely present throughout the year, C. lepadiformis grows in spring and may show great variation in abundance from year to year.

Bibliography

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