Musculus discors beds on moderately exposed circalittoral rock

English name: Musculus discors beds on moderately exposed circalittoral rock

Quick facts

EUNIS habitat type code A4.242
Bern Convention Included in a Resolution 4 habitat type at a higher level (A4)

Description (English)

This biotope typically occurs on the upper faces of moderately exposed, moderately tide-swept bedrock, boulders and cobbles in slightly silty conditions. The mussel Musculus discors occurs in dense mats and occasionally completely coats all available surfaces. There is also often a layer of pseudofaeces, forming a thick, silty matrix. A relatively diverse fauna of cushion and branching sponges is often present on rocky outcrops and other hard substratum that is free of mussels. These include Tethya aurantium, Scypha ciliata, Pachymatisma johnstonia, Dysidea fragilis, Cliona celata and Stelligera stuposa. There may be isolated clumps of silt-tolerant bryozoans such as Flustra foliacea and Bugula plumosa. Various species may be observed on top of the mussels, including Asterias rubens, Crossaster papposus and the brittlestar Ophiura albida. Occasional Alcyonium digitatum and clumps of the hydroid Nemertesia antennina are found attached to rocky outcrops and boulders whilst the anemone Urticina felina may be seen in crevices in the rock or on gravely patches between boulders. Colonial ascidians such as Clavelina lepadiformis and didemnids may occasionally be present. A wide range of seaweeds may be present, including Dictyota dichotoma, Plocamium cartliagineum, Dictyopteris membranacea, Cryptopleura ramosa and Heterosiphonia plumosa. The crab Cancer pagurus may be observed in crevices. The majority of the records for this biotope are from the Lleyn Peninsula.

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Algae Cryptopleura ramosa
Algae Dictyota dichotoma
Algae Heterosiphonia plumosa
Invertebrates Alcyonium digitatum
Invertebrates Asterias rubens
Invertebrates Bugula plumosa
Invertebrates Cancer pagurus
Invertebrates Clavelina lepadiformis
Invertebrates Cliona celata
Invertebrates Crossaster papposus
Invertebrates Dysidea fragilis
Invertebrates Flustra foliacea
Invertebrates Musculus discors
Invertebrates Nemertesia antennina
Invertebrates Ophiura albida
Invertebrates Pachymatisma johnstonia
Invertebrates Stelligera stuposa
Invertebrates Tethya aurantium
Invertebrates Urticina felina
Species scientific name English common name Species group
Cryptopleura ramosa Algae
Dictyota dichotoma Algae
Heterosiphonia plumosa Algae
Alcyonium digitatum Invertebrates
Asterias rubens Invertebrates
Bugula plumosa Invertebrates
Cancer pagurus Invertebrates
Clavelina lepadiformis Invertebrates
Cliona celata Invertebrates
Crossaster papposus Invertebrates
Dysidea fragilis Invertebrates
Flustra foliacea Invertebrates
Musculus discors Invertebrates
Nemertesia antennina Invertebrates
Ophiura albida Invertebrates
Pachymatisma johnstonia Invertebrates
Stelligera stuposa Invertebrates
Tethya aurantium Invertebrates
Urticina felina Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 CR.MCR.CMus.Mdis <I>Musculus discors</I> beds on moderately exposed circalittoral rock source
CORINE Land Cover 5.2.3. Sea and ocean n/a
For relation to plant communities (syntaxa), see Vegetation types

History

Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200410 A4.242 Musculus discors beds on moderately exposed circalittoral rock same
EUNIS Habitat Classification 200308 A3.642 Musculus discors beds on moderately exposed circalittoral rock same
EUNIS Habitat Classification 200202 A3.642 Musculus discors beds on moderately exposed circalittoral rock same
EUNIS Habitat Classification 199910 A3.642 Musculus discors beds on moderately exposed circalittoral rock same
MNCR BioMar 97.06 (Britain & Ireland) MCR.M.Mus Musculus discors beds on moderately exposed circalittoral rock same
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