Ascophyllum nodosum on full salinity mid eulittoral rock
|EUNIS habitat type||code MA123E1|
|Relation to||Resolution 4 habitat type (used for designation of Emerald sites)|
Bedrock, stable boulders and cobbles in the mid-eulittoral zone of moderately exposed to extremely sheltered shores, in fully marine conditions, characterised by a dense canopy of the wrack Ascophyllum nodosum. Another wrack Fucus vesiculosus may in some places co-dominate the canopy. The hydroid Dynamena pumila can form colonies on the wracks F. vesiculosus and Fucus serratus. Variations in the ratio of A. nodosum and F. vesiculosus in the overlying canopy have little effect on the under-storey species. Beneath the canopy are a diverse array of filamentous and foliose red seaweeds, including Mastocarpus stellatus, Chondrus crispus, Gelidium pusillum and coralline crusts. The filamentous red seaweed Polysiphonia lanosa is usually present on A. nodosum as an epiphyte. A few green seaweeds including Cladophora rupestris and Enteromorpha spp. are also present in moderate to low densities. On the bedrock and boulders beneath the seaweed canopy is a fauna including the barnacle Semibalanus balanoides, the limpet Patella vulgata, tube-forming spirorbid polychaetes and the anemone Actinia equina. The latter can be present in damp cracks and crevices. On and among the seaweeds are mobile species including the winkles Littorina littorea and Littorina obtusata, the whelk Nucella lapillus or even the crab Carcinus maenas. At the top of the A. nodosum zone there might be the occasional presence of the olive green lichen Verrucaria mucosa.
Situation: This biotope is usually found between the wrack Fucus spiralis (unit MA1-23C) and F. serratus dominated biotopes (MA1-23F), although on some shores a narrow zone of F. vesiculosus (MA1-23D) may occur immediately above the A. nodosum. With increasing wave exposure the A. nodosum canopy is replaced by F. vesiculosus (MA1-243; MA1-23D). This unit can occur on more exposed shores, where there is localised shelter.
Temporal variation: A. nodosum can reach an age of 25 years on sheltered shores and the communities are, once established, usually very stable. F. vesiculosus or F. serratus can occur in patches where the A. nodosum has been removed.
Source: EUNIS habitat classification
Relation to other habitat types mentioned in legal instruments
Relation to vegetation types (syntaxa)Not available
Species mentioned in habitat description
|Species scientific name||English common name||Species group|
|Nucella lapillus||Dog whelk||Invertebrates|
|Classification||Code||Habitat type name||Relationship type|
|EUNIS Habitat Classification 2007 (revised descriptions 2012)||A1.3141||Ascophyllum nodosum on full salinity mid eulittoral rock||same|
|Classification||Code||Habitat type name||Relationship type||Comment|
|EUNIS Habitat Classification 200410||A1.3141||Ascophyllum nodosum on full salinity mid eulittoral rock||same|
|EUNIS Habitat Classification 200308||A1.3141||Ascophyllum nodosum on full salinity mid eulittoral rock||same|
|EUNIS Habitat Classification 200202||A1.3141||Ascophyllum nodosum on full salinity mid eulittoral rock||same|
|EUNIS Habitat Classification 199910||A1.3141||Ascophyllum nodosum on full salinity mid eulittoral rock||same|
|MNCR BioMar 97.06 (Britain & Ireland)||SLR.F.Asc.Asc||Ascophyllum nodosum on full salinity mid eulittoral rock||same|