2. Données et outils
  3. Rechercher un habitat
  4. MC1-231 - Ascidies solitaires, dont Ascidia mentula et Ciona intestinalis, sur roche du circalittoral abritée des vagues en Atlantique
  5. Description
MC1-231 - Ascidies solitaires, dont Ascidia mentula et Ciona intestinalis, sur roche du circalittoral abritée des vagues en Atlantique

Solitary ascidians, including Ascidia mentula and Ciona intestinalis, on wave-sheltered Atlantic circalittoral rock

MC1-232 - Grandes ascidies solitaires et éponges dressées sur roche du circalittoral abritée en Atlantique

Classification des habitats EUNIS 2022

Descriptif de l'habitat

This biotope predominantly occurs on the upper faces of wave-sheltered (often sealochs) circalittoral bedrock, boulder and cobble slopes with little tidal flow. Apart from the solitary ascidians Ciona intestinalis and Ascidia mentula, this biotope has a rather barren, pink appearance (due to the encrusting red algae), possibly due to grazing pressure from the sea urchin Echinus esculentus. Other organisms found encrusting the rocky surface include the polychaete Pomatoceros triqueter and the cup coral Caryophyllia smithii. Other species occasionally encountered include Alcyonium digitatum, Asterias rubens, Pagurus berhardus, Crossaster papposus, Antedon bifida and Metridium senile. Crustaceans such as Munida rugosa and Cancer pagurus may be recorded in crevices. Two variants of this biotope exist: Units MC1-2311 and MC1-2312. MC1-2312 occurs where is a dense carpet of brittlestars which sometimes completely cover the rocky substratum. Species present include Ophiothrix fragilis, Ophiocomina nigra and Ophiura albida.
Temporal variation: The abundance of C. intestinalis tends to fluctuate seasonally, so it may appear absent at a site at one time of year and then be present at other times, altering the visual appearance of the biotope. Other solitary ascidian species such as A. mentula and Ascidiella aspersa tend to be longer-lived (approximately 7 years and 3 years, respectively).

Bibliographie

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