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Concept: [Alaria esculenta], [Mytilus edulis] and coralline crusts on very exposed sublittoral fringe bedrock in the eunishabitats vocabulary

Concept URI http://eunis.eea.europa.eu/eunishabitats/A3.1111
Preferred label [Alaria esculenta], [Mytilus edulis] and coralline crusts on very exposed sublittoral fringe bedrock
Definition Very exposed sublittoral fringe bedrock characterised by the kelp [Alaria esculenta] and dense patches of small individuals of the mussel [Mytilus edulis], both of which grow over a dense cover of encrusting coralline algae. Foliose red seaweeds may also be present, but the species composition and their abundance vary between sites. Species such as [Corallina officinalis] occur widely. The kelp [Laminaria digitata] is usually absent, although stunted plants may be present at a few sites. The limpet [Patella vulgata] and the barnacle [Semibalanus balanoides] are often common. Patches of anthozoans and the hydroid [Tubularia] spp. occur in more wave-surged areas. In extremely exposed areas the [A. esculenta] zone can extend as deep as 15 m, where it has less [S. balanoides], [M. edulis] and greater densities of [Tubularia] spp. (e.g. Barra and shallow areas of Rockall). Situation: This biotope is most commonly found beneath the mussel-barnacle zone (MytB) of very exposed shores and above the upper infralittoral [Laminaria hyperborea] forest (LhypR or LhypFa). It is at the extremely wave-surged sites, such as St Kilda, that LhypFa occurs below Ala.Myt. Occasionally, the [A. esculenta] zone occurs below a narrow but dense band of red seaweeds: typically [Mastocarpus stellatus] and/or [Palmaria palmata] and [Corallina officinalis] (Mas) or very occasionally [Himanthalia elongata] (Him). A dense turf of [C. officinalis] (Coff) occurs above the [A. esculenta] zone at a few extremely exposed sites, particularly on steep or vertical rock. On less exposed shores, however, an [A. esculenta] dominated zone may lie immediately above a narrow [L. digitata] zone (Ldig). Ala.Myt can also occur on less exposed steep or vertical shores, where wave-surge restricts the growth of [L. digitata] which generally dominates the sublittoral fringe rock on moderately exposed shores. On seasonally unstable boulders or sites subject to disturbance by strong wave-action, a mixed kelp canopy that characterises LsacSac may occur beneath the Ala.Myt zone instead of the ubiquitous [L. hyperborea] forest; this is most common on the Shetland isles. Temporal variation: At very exposed sites, [A. esculenta] may have been so wave-battered during the season as to be reduced to a tattered midrib with no blades, altering the general appearance of the biotope. Where Ala.Myt occurs on boulders and/or sites subject to disturbance during severe weather conditions, rock that is scoured clean may then be rapidly colonised by fast-growing green algae such as [Enteromorpha] spp. An assemblage of rapidly colonising species that characterise the disturbed Sac biotope may also develop in the sublittoral fringe. A species that can fluctuate in huge numbers at these sites is the starfish [Asterias rubens], sometimes forming dense aggregations across the narrow [A. esculenta] band whilst feeding on the mussels.
Notation A3.1111
Status Valid
Status Modified 2014-01-31
Accepted Date 2014-01-31
Not Accepted Date
Has broader
Has exact match