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Marine Habitat Classification

Description of biotope or habitat type

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   Fucus vesiculosus on variable salinity mid eulittoral boulders and stable mixed substrata

Physical habitat description

Salinity Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams
Substratum Boulders; Pebbles and cobbles on sand/mud
Zone Eulittoral
Depth Band
Other Features Variable salinity and/or silt

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.LLR.FVS.FvesVS <I>Fucus vesiculosus</I> on variable salinity mid eulittoral boulders and stable mixed substrata

  • 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.


Sheltered to extremely sheltered mid eulittoral pebbles and cobbles lying on sediment subject to variable salinity and characterised by the wrack Fucus vesiculosus. The wrack Ascophyllum nodosum can occasionally be found on larger boulders, while the barnacles Semibalanus balanoides and Austrominius modestus and the mussel Mytilus edulis can be present on cobbles. Winkles, particularly Littorina littorea, commonly graze on the seaweeds, while Littorina saxatilis can be found in crevices. Ephemeral seaweeds such as Ulva intestinalis can occupy available space. Patches of sediment found between the hard substrata often contains the lugworm Arenicola marina or the sand mason Lanice conchilega, while the crab Carcinus maenas, gammarids and amphipods occur on and under cobbles.


Fves.VS can be found below the biotope dominated by the wracks Fucus spiralis or Fucus ceranoides (Fspi.X; Fcer) or a community dominated by S. balanoides, P. vulgata and L. littorea (BLitX). It is found above a community dominated by M. edulis (Myt.Myt) or the wrack Fucus serratus (Fserr.VS).

Temporal variation

Some variation in the ephemeral seaweeds and their abundance depending on the season is likely.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Fucus vesiculosus 46 Common 81-100%
Semibalanus balanoides 10 Frequent 41-60%
Ulva intestinaloides 8 Frequent 41-60%
Littorina littorea 7 Occasional 41-60%
Carcinus maenas 6 Occasional 41-60%
Ascophyllum nodosum 3 Occasional 21-40%
Austrominius modestus 3 Frequent 21-40%
Mytilus edulis 3 Occasional 41-60%
Gammaridae 2 Frequent 21-40%
Littorina saxatilis 2 Frequent 21-40%

Similar biotopes or habitat types

Occurs in marine conditions, but otherwise a similar habitat. Higher species richness and the F. vesiculosus canopy is more dense due to less siltation. The limpet Patella vulgata is present.

Occur on similar substrata, but in fully marine conditions. Similar species composition though higher species richness. P. vulgata and L. saxatilis.

Occur on more unstable substrata, which do not allow F. vesiculosus (Occasional) to become established in any high abundance.

Classification history of this biotope or habitat type

Classification version Code
1997 (97.06) SLR.Fves (part)

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