Frequency of occurrence in Britain RARE

Biotope: Robust fucoids or red seaweeds

Community: Fucus distichus and Fucus spiralis f. nana on extremely exposed upper shore rock

 Frequency of occurrence in Britain SCARCE

Biotope: Mytilus (mussels) and barnacles

Community: Barnacles, Patella spp. and Fucus vesiculosus f. linearis on exposed eulittoral rock

Biotope: Red seaweeds (moderately exposed shores)

Community: Mastocarpus stellatus and Chondrus crispus on very to moderately exposed lower eulittoral rock

Biotope: Robust faunal cushions and crusts (surge gullies and caves)

Community: Dendrodoa grossularia and Clathrina coriacea on wave-surged vertical infralittoral rock

 Frequency of occurrence in Britain UNCOMMON

Biotope: Lichens of algal crusts

Community: Prasiola stipitata on nitrate-enriched supralittoral or littoral fringe

Biotope: Red seaweeds (moderately exposed shores)

Community: Palmaria palmata on very to moderately exposed lower eulittoral rock

Biotope: Ephemeral green or red seaweeds

Community: Enteromorpha spp. on freshwater-influenced or unstable upper eulittoral rock

Biotope: Kelp with cushion fauna, foliose red seaweeds or coralline crusts (exposed rock)

Community: Laminaria hyperborea forest with dense foliose red seaweeds on exposed upper infralittoral rock

Biotope: Kelp with cushion fauna, foliose red seaweeds or coralline crusts (exposed rock)

Community: Laminaria hyperborea park with dense foliose red seaweeds on exposed lower infralittoral rock

Biotope: Robust faunal cushions and crusts (surge gullies and caves)

Community: Balanus crenatus and/or Pomatoceros triqueter with spirorbid worms and coralline crusts on severely scoured vertical infralittoral rock

Biotope: Silted kelp (stable rock)

Community: Mixed Laminaria hyperborea and Laminaria saccharina park on sheltered lower infralittoral rock

  Frequency of occurrence in Britain COMMON

Biotope: Lichens of algal crusts

Community: Verrucaria maura on littoral fringe rock

Biotope: Lichens of algal crusts

Community: Verrucaria maura and Porphyra umbilicalis on very exposed littoral fringe rock

Biotope: Lichens of algal crusts

Community: Verrucaria maura and sparse barnacles on exposed littoral fringe

Biotope: Mytilus (mussels) and barnacles

Community: Mytilus edulis and barnacles on very exposed eulittoral rock

Biotope: Robust fucoids or red seaweeds

Community: Himanthalia elongata and red seaweeds on exposed lower eulittoral rock

Biotope: Rockpools

Community: Fucoids and kelps in deep eulittoral rockpools

Biotope: Kelp with cushion fauna, foliose red seaweeds or coralline crusts (exposed rock)

Community: Alaria esculenta, Mytilus edulis and coralline crusts on very exposed sublittoral fringe bedrock

Biotope: Kelp and red seaweeds (moderately exposed rock)

Community: Laminaria hyperborea park and foliose red seaweeds on moderately exposed lower infralittoral rock

Biotope: Grazed kelp with algal crusts

Community: Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock

Biotope: Grazed kelp with algal crusts

Community: Grazed Laminaria hyperborea park with coralline crusts on lower infralittoral rock

Biotope: Fauna and seaweeds (shallow vertical rock)

Community: Alcyonium digitatum with a bryozoan, hydroid and ascidian turf on moderately exposed vertical infralittoral rock

Biotope: Faunal crusts or short turfs (exposed rock)

Community: Coralline crusts, Parasmittina trispinosa, Caryophyllia smithii, Haliclona viscosa, polyclinids and sparse Corynactis viridis on very exposed circalittoral rock

 Frequency of occurrence in Britain VERY COMMON

Biotope: Lichens of algal crusts

Community: Verrucaria maura on very exposed to very sheltered upper littoral

Biotope: Mytilus (mussels) and barnacles

Community: Barnacles and Patella spp. on exposed or moderately exposed, or vertical sheltered, eulittoral rock

Biotope: Mytilus (mussels) and barnacles

Community: Semibalanus balanoides on exposed or moderately exposed, or vertical sheltered, eulittoral rock

Biotope: Barnacle or fucoids (moderately exposed shores)

Community: Fucus serratus on moderately exposed lower eulittoral rock

Biotope: Dense fucoids (stable rock)

Community: Pelvetia canaliculata on sheltered littoral fringe rock

Biotope: Dense fucoids (stable rock)

Community: Fucus spiralis on moderately exposed to very sheltered upper eulittoral rock

Biotope: Dense fucoids (stable rock)

Community: Ascophyllum nodosum on very sheltered mid eulittoral rock

Biotope: Rockpools

Community: Green seaweeds (Enteromorpha spp. and Cladophora spp.) in upper shore rockpools

Biotope: Rockpools

Community: Corallina officinalis and coralline crusts in shallow eulittoral rockpools

Biotope: Kelp and red seaweeds (moderately exposed rock)

Community: Laminaria digitata on moderately exposed or tide-swept sublittoral fringe rock

Biotope: Kelp and red seaweeds (moderately exposed rock)

Community: Laminaria digitata on moderately exposed sublittoral fringe rock

Biotope: Kelp and red seaweeds (moderately exposed rock)

Community: Laminaria hyperborea forest and foliose red seaweeds on moderately exposed upper infralittoral rock

Biotope: Brittlestar beds

Community: Ophiothrix fragilis and/or Ophiocomina nigra beds on slightly tide-swept circalittoral rock or mixed substrata

 Not classified but generally INFREQUENT in Britain

Biotope: Kelp with cushion fauna, foliose red seaweeds or coralline crusts (exposed rock)

Community: Laminaria saccharina and/or Saccorhiza polyschides on exposed infralittoral rock

Biotope: Kelp with cushion fauna, foliose red seaweeds or coralline crusts (exposed rock)

Community: Foliose red seaweeds on exposed or moderately exposed lower infralittoral rock

Biotope: Robust faunal cushions and crusts (surge gullies and caves)

Community: Foliose seaweeds and coralline crusts in surge gully entrances

Biotope: Robust faunal cushions and crusts (surge gullies and caves)

Community: Sponge crusts, anemones and Tubularia indivisa in shallow infralittoral surge gullies

Biotope: Robust faunal cushions and crusts (surge gullies and caves)

Community: Sponge crusts and colonial ascidians on wave-surged vertical infralittoral rock

Biotope: Robust faunal cushions and crusts (surge gullies and caves)

Community: Sponge crusts, colonial (polyclinid) ascidians and a bryozoan/hydroid turf on wave-surged vertical or overhanging infralittoral rock

Biotope: Kelp and red seaweeds (moderately exposed rock)

Community: Laminaria hyperborea and foliose red seaweeds on moderately exposed infralittoral rock

Biotope: Sand or gravel-affected or disturbed kelp and seaweed communities

Community: Mixed kelps with scour-tolerant and opportunistic foliose red seaweeds on scoured or sand-covered infralittoral rock

Biotope: Fauna and seaweeds (shallow vertical rock)

Community: Corynactis viridis, Metridium senile and Alcyonium digitatum on exposed or moderately exposed vertical infralittoral rock

Biotope: Faunal crusts or short turfs (exposed rock)

Community: Pomatoceros triqueter, Balanus crenatus and bryozoan crusts on mobile circalittoral cobbles and pebbles

Biotope: Alcyonium-dominated communities (tide-swept/vertical)

Community: Alcyonium digitatum, Pomatoceros triqueter, algal and bryozoan crusts on vertical exposed circalittoral rock

Biotope: Grazed fauna (moderately exposed or sheltered rock)

Community: Faunal and algal crusts, Echinus esculentus, sparse Alcyonium digitatum and grazing-tolerant fauna on moderately exposed circalittoral rock

Biotope: Laminaria saccharina (sugar kelp) and filamentous seaweeds (mixed sediment)