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Marine Habitat Classification

Description of biotope or habitat type

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   Submerged fucoids, green or red seaweeds (low salinity infralittoral rock)

Physical habitat description

Salinity Reduced (18-30ppt), Low (<18ppt)
Wave exposure Extremely sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Bedrock, boulders, cobbles, pebbles
Zone Infralittoral
Depth Band 0-5 m
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 IR.LIR.Lag Submerged fucoids, green or red seaweeds (low salinity infralittoral rock)

  • 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'
  • Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat

Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.


Very shallow submerged rocky habitats in lagoons, subject to reduced or permanently low salinity conditions. These particular conditions lead to a variety of seaweed-dominated communities, which include fucoids and green filamentous species. The fucoids, more typical of intertidal habitats, penetrate into the subtidal under the reduced salinity conditions which are not tolerated by kelps.


No situation data available.

Temporal variation


Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Fucus ceranoides 14 Common 21-40%
Fucus serratus 13 Common 41-60%
Ulva intestinalis 12 Frequent 61-80%
Ectocarpaceae 8 Frequent 21-40%
Fucus vesiculosus 7 Frequent 21-40%
Mysidae 5 Frequent 21-40%
Carcinus maenas 4 Occasional 21-40%
Ascophyllum nodosum 3 Occasional 21-40%
Chorda filum 3 Frequent 21-40%
Cladophora rupestris 3 Frequent 21-40%
Littorina littorea 3 Frequent 21-40%
Corallinaceae 2 Occasional 21-40%
Mytilus edulis 2 Occasional 21-40%
Polyides rotunda 2 Frequent 21-40%
Chondrus crispus 1 Occasional 21-40%
Mastocarpus stellatus 1 Occasional 21-40%

Similar biotopes or habitat types

Not applicable or unknown.

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