Moderately exposed infralittoral rock with kelp



GB distribution

Compiled by: Leigh Jones, Joint Nature Conservation Committee, Monkstone House, City Road, Peterborough PE1 IJY, UK.

Derived, in part, from: the UK marine biotope classification (Connor et al. 1997b) and a review undertaken for the UK Marine SACs Project (Birkett et al., 1998).


Classification Code Biotope(s)
Europe (EUNIS Nov 1999) A3.2 Infralittoral rock moderately exposed to wave action and/or currents and tidal streams
Wadden Sea 03.02.06 Benthic zone of the shallow coastal waters with hard bottom and rich macrophytes
Britain/Ireland (MNCR BioMar 97.06) MIR.KR


Kelp with red seaweeds (moderately exposed)

Grazed kelp with algal crusts

France (ZNIEFF-MER) III.9.3.3 Faciès à Laminaria hyperborea-Laminaria ochroleuca: sous-faciès à L. hyperborea en population pure (eau claire, mode battu à très battu)


MIR.KR. Infralittoral rock subject to moderate wave exposure, or moderately strong tidal streams on more sheltered coasts. On bedrock and stable boulders there is typically a narrow band of kelp Laminaria digitata in the sublittoral fringe which lies above the Laminaria hyperborea forest and park. Associated with the kelp are communities of seaweeds, predominantly reds and including a greater variety of more delicate Filamentous types than found on more exposed coasts (EIR.KFaR). The faunal component of the understorey is also less prominent than in EIR.KFaR.

MIR.GzK. Infralittoral rock, typically dominated by the kelp Laminaria hyperborea but where the rock beneath is intensely grazed by urchins giving a barren algal-encrusted rock surface. In some areas the upper parts of the kelp stipes may be free from grazing pressure and support a typical kelp stipe flora. Under intense grazing pressure, erect algae are absent and animals are confined to crevices and under-boulder habitats where urchins cannot penetrate. Where grazing is less severe, some erect algae, such as Desmarestia aculeata, and a certain animals (eg. Alycyonium digitatum and Nemertesia antennina) may occur. Dense aggregations of brittlestars (Ophiothrix fragilis and Ophiocomina nigra) produce a similarly barren community, through their smothering effect.

GB distribution

(from MNCR database in March 1999)












Habitat requirements

Species composition and biodiversity

Ecological relationships

Sensitivity to human activities

Conservation and protection status