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Marine Habitat Classification

Description of biotope or habitat type

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   Fucus spiralis on sheltered variable salinity upper eulittoral rock

Physical habitat description

Salinity Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams
Substratum Bedrock; stable boulders; cobbles
Zone Eulittoral - upper
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.LLR.FVS.FspiVS <I>Fucus spiralis</I> on sheltered variable salinity upper eulittoral 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'

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


Sheltered to extremely sheltered upper eulittoral bedrock or mixed substrata (boulders, large cobbles or shells on mud) in variable salinity conditions characterised by a band of the spiral wrack Fucus spiralis. The ephemeral green seaweed Ulva intestinalis is usually found in this species poor biotope. The barnacles Semibalanus balanoides and Austrominius modestus can be found where suitable substrata are available, while gammarids can be found underneath the fronds of F. spiralis and/or underneath the boulders and cobbles. Also found underneath the fronds and among the boulders are the winkles Littorina saxatilis and Littorina littorea and the crab Carcinus maenas.


This zone usually lies below a zone dominated by the wrack Pelvetia canaliculata (Pel) and occasional clumps of P. canaliculata may be present (usually less than common) amongst the F. spiralis. In areas of extreme shelter and variable salinity conditions (e.g. in Scottish sea lochs), the P. canaliculata and F. spiralis zones often merge together forming a very narrow band. Fspi.VS occurs above the wracks Ascophyllum nodosum (Asc.VS) and/or Fucus vesiculosus (Fves.VS) zones and these two fucoids may also occur, although F. spiralis always dominates. It can also be found above a zone dominated by the wrack Fucus ceranoides (Fcer).

Temporal variation

During the summer months ephemeral green seaweeds such as E. intestinalis can be common.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Fucus spiralis 62 Common 81-100%
Ulva intestinalis 10 Occasional 41-60%
Semibalanus balanoides 5 Occasional 61-80%
Gammaridae 4 Occasional 21-40%
Carcinus maenas 4 Occasional 41-60%
Austrominius modestus 3 Occasional 21-40%
Littorina saxatilis 3 Occasional 61-80%
Littorina littorea 2 Occasional 41-60%

Similar biotopes or habitat types

Occurs in fully marine conditions. It has a higher species richness, and species such as the limpet Patella vulgata are usually present. More seaweeds including the brown A. nodosum and Fucus vesiculosus and the red non-calcified crust Hildenbrandia rubra occur.

Occurs on moderately exposed bedrock in fully marine conditions. It has a higher species richness, and species such as the limpet Patella vulgata and the lichens V. maura and Verrucaria mucosa are usually present.

Classification history of this biotope or habitat type

Classification version Code
1997 (97.06) SLR.Fspi (part)
1995 LRK.FSP

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