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Marine Habitat Classification

Description of biotope or habitat type

To understand more about what this page is describing, see How to use the classification. See also How to cite.

   Kelp in variable or reduced salinity

Physical habitat description

Salinity Full (30-35 ppt), Reduced (18-30ppt), Variable (18-35 ppt), Low (<18ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Bedrock, boulders & cobbles
Zone Infralittoral, Sublittoral fringe
Depth Band 0-5 m, 5-10 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.KVS Kelp in variable or reduced salinity

  • 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 wave-sheltered bedrock, boulders and cobbles subject to only weak tidal streams in the sublittoral fringe and infralittoral zone, in areas of variable/reduced salinity. This biotope complex is characterised by the kelp Saccharina latissima and coralline crusts such as Lithothamnion glaciale. Grazers such as the urchins Psammechinus miliaris and Echinus esculentus, and the gastropods Steromphala cineraria and Buccinum undatum may be present. The tube-dwelling polychaete Spirobranchus triqueter, the ascidians Ciona intestinalis, Corella parallelogramma and Ascidiella scabra, the barnacle Balanus crenatus, the starfish Asterias rubens and the brittlestar Ophiothrix fragilis may also be present. Red algal communities are composed primarily of Phycodrys rubens. The crabs Carcinus maenas and Pagurus bernhardus, and the bivalve Modiolus modiolus may also be observed.


No situation data available.

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
Psammechinus miliaris 12 Frequent 61-80%
Spirobranchus triqueter 10 Frequent 61-80%
Corallinaceae 7 Common 41-60%
Asterias rubens 7 Frequent 61-80%
Carcinus maenas 4 Occasional 61-80%
Phycodrys rubens 4 Occasional 41-60%
Lithothamnion glaciale 3 Common 21-40%
Pagurus bernhardus 3 Occasional 41-60%
Buccinum undatum 2 Occasional 41-60%
Ciona intestinalis 2 Occasional 41-60%
Corella parallelogramma 2 Occasional 21-40%
Steromphala cineraria 2 Frequent 21-40%
Ophiothrix fragilis 2 Frequent 21-40%
Echinus esculentus 2 Occasional 21-40%
Ascidiella scabra 1 Occasional 21-40%
Balanus crenatus 1 Occasional 21-40%
Modiolus modiolus 1 Occasional 21-40%

Similar biotopes or habitat types

Not applicable or unknown.

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