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Marine Habitat Classification

Description of biotope or habitat type

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   Mussels and fucoids on moderately exposed shores

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed
Tidal streams
Substratum Bedrock; large boulders
Zone Eulittoral - lower, Eulittoral - mid
Depth Band
Other Features

Download comparative physical and biological data. The comparative tables enable a rapid comparison of the species composition and principal physical characteristics between a given set of biotopes.

Distribution of habitat LR.MLR.MusF Mussels and fucoids on moderately exposed shores

  • Records used to define the biotope (core records)
  • Other records assigned to this biotope, marked as 'certain'
  • Other records assigned to this biotope, marked as 'uncertain'

Point data based on records in the UK Marine Recorder Snapshot.


Mid and lower eulittoral exposed to moderately exposed bedrock, often with nearby sediment, may be densely covered by large individuals of the mussel Mytilus edulis. Three biotopes have been described: In the mid eulittoral, the mussels may form a band or large patches with scattered bladder wrack Fucus vesiculosus (MytFves). In the lower eulittoral a range of red seaweeds including Mastocarpus stellatus and Palmaria palmata occur amongst the mussels (in higher abundance than the mid eulittoral) (MytFR). Clay outcrops in the mid to lower eulittoral may be bored by a variety of piddocks including Pholas dactylus, Barnea candida and Petricolaria pholadiformis, while the surface is characterised by small clumps of the mussel M. edulis, the barnacle Austrominius modestus and the winkle Littorina littorea (MytPid). Ephemeral green seaweeds such as Ulva intestinalis and Ulva lactuca commonly occur on the shells of the mussels. Barnacles are common on both the mussel valves and on patches of bare rock, where the limpet Patella vulgata is found as well, often at high abundance. The whelk Nucella lapillus and a range of littorinids also occur within the mussel bed. A dense M. edulis community may be found on more sheltered coasts on mixed substrata (Myt).


Above this biotope complex is a M. edulis and S. balanoides dominated zone (MF) or a F. vesiculosus dominated biotope (FvesB). In the lower eulittoral zone below is a zone dominated by the wrack Fucus serratus, M. edulis and a variety of red seaweeds (BF) while kelp dominate the sublittoral fringe.

Temporal variation

No temporal variation data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Mytilus edulis 30 Abundant 81-100%
Semibalanus balanoides 12 Common 81-100%
Patella vulgata 7 Frequent 61-80%
Nucella lapillus 7 Frequent 61-80%
Ulva intestinalis 5 Frequent 41-60%
Littorina littorea 4 Frequent 41-60%
Fucus vesiculosus 4 Common 21-40%
Fucus serratus 3 Common 41-60%
Mastocarpus stellatus 3 Frequent 41-60%
Ulva lactuca 3 Occasional 41-60%
Corallinaceae 2 Occasional 41-60%
Palmaria palmata 2 Frequent 41-60%

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code
1997 (97.06) MLR.MF
1996 (6.95) MLR.Myt

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