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  4. MC1-51 - Biocénose coralligène
  5. Description
MC1-51 - Biocénose coralligène

Coralligenous biocenosis

MC1-52 - Biocénose des grottes semi-obscures et surplombs en Méditerranée

Classification des habitats EUNIS 2022

Descriptif de l'habitat

The distribution of the coralligenous assemblage is subject to a combination of decisive biotic and abiotic factors. The main factors are light, movement of the water, temperature, the deposit of sediment and biological interactions.
The coralligenous is found on rock faces or on rocks where calcareous algae can form biogenic constructions. Due to their sensitivity to light, these calcareous algae are restricted upwards by strong illumination and have an extension downwards, restricted by the quantity of luminous energy needed for their photosynthesis. The average depth of this habitat is between 30 and 90 meters. When the water is very clear, the coralligenous begins and ends very deep (60-130 meters), but when the water is turbid, it rises to shallower depths (10/15-40 meters). Such a rise may also be seen along dimly lit rock faces (north- facing, for example). The thermal scope of seasonal variation for this habitat is variable, and a certain tolerance of fluctuation in salinity has been observed; however, the sedimentation of fine particles is particularly harmful.
The coralligenous can present various physiognomical types between the two most typical forms on our coasts, which are:
- the rock wall coralligenous which covers the rocky substrata beyond the photophilous algae, with more or less thick concretions and an abundance of big erect invertebrates, such as the Paramuricea clavata, Eunicella spp., Leptogorgia sarmentosa gorgonians and the Axinella polypoides sponge
- the coralligenous concretion forming biogenous clumps that can be several meters thick and cover big horizontal or non-horizontal surfaces. This coralligenous is a fully biogenic habitat. The essential species are the constructive Corallinaceae and Peyssonneliaceae species; the structure of these clumps is highly anfractuous, with many cavities of great richness (parts of the biocenosis of semi-dark caves).

Bibliographie

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