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Marine Habitat Classification

Description of biotope or habitat type

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   Laminaria hyperborea on tide-swept, infralittoral rock

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Extremely exposed, Very exposed, Exposed, Moderately exposed
Tidal streams Strong (3-6 kn), Moderately strong (1-3 kn)
Substratum Bedrock & boulders
Zone Infralittoral
Depth Band 0-5 m, 5-10 m, 10-20 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.MIR.KR.LhypT <I>Laminaria hyperborea</I> on tide-swept, 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.


Wave exposed to moderately wave exposed, tide-swept bedrock and boulders with Laminaria hyperborea, characterised by a rich under-storey and stipe flora of foliose seaweeds including the brown seaweed Dictyota dichotoma. The kelp stipes support epiphytes such as Cryptopleura ramosa and Phycodrys rubens. At some sites, instead of being covered by red seaweeds, the kelp stipes are heavily encrusted by the ascidian Botryllus schlosseri. Epilithic seaweeds Delesseria sanguinea, Plocamium cartilagineum Heterosiphonia plumosa, Hypoglossum hypoglossoides, Callophyllis laciniata, Kallymenia reniformis, Brongniartella byssoides and crustose seaweeds commonly occur beneath the kelp. The kelp fronds are often covered with growth of the hydroid Obelia geniculata or the bryozoan Membranipora membranacea. On the rock surface, a rich fauna comprising the bryozoan Electra pilosa, the sponge Pachymatisma johnstonia, anthozoans such as Alcyonium digitatum, Sagartia elegans and Urticina felina, colonial ascidians such as Clavelina lepadiformis, the calcareous tubeworm Pomatoceros triqueter and the barnacle Balanus crenatus occur. More mobile species include the gastropod Calliostoma zizyphinum, the crab Cancer pagurus and the echinoderms Asterias rubens and Echinus esculentus. Two variants have been described: Tide-swept kelp forest (LhypT.Ft) and tide-swept kelp park (LhypT.Pk).


This biotope occurs below Alaria esculenta (Ala) at exposed sites or L. digitata (Ldig.Ldig) at moderately exposed locations. With increasing depth the kelp density diminishes to become tide-swept kelp park (LhypT.Pk).

Temporal variation


Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Pachymatisma johnstonia 1 Occasional 41-60 %
Obelia geniculata 1 Frequent 21-40 %
Alcyonium digitatum 2 Occasional 41-60 %
Urticina felina 1 Occasional 41-60 %
Sagartia elegans 1 Occasional 21-40 %
Pomatoceros triqueter 1 Occasional 21-40 %
Balanus crenatus 2 Frequent 41-60 %
Cancer pagurus 1 Occasional 41-60 %
Calliostoma zizyphinum 1 Occasional 41-60 %
Membranipora membranacea 2 Frequent 41-60 %
Electra pilosa 1 Frequent 21-40 %
Asterias rubens 3 Occasional 61-80 %
Echinus esculentus 2 Occasional 41-60 %
Clavelina lepadiformis 2 Occasional 41-60 %
Botryllus schlosseri 1 Occasional 41-60 %
Corallinaceae 5 Frequent 61-80 %
Callophyllis laciniata 2 Occasional 41-60 %
Kallymenia reniformis 1 Occasional 41-60 %
Plocamium cartilagineum 6 Frequent 61-80 %
Heterosiphonia plumosa 2 Frequent 41-60 %
Cryptopleura ramosa 3 Frequent 61-80 %
Delesseria sanguinea 6 Frequent 61-80 %
Hypoglossum hypoglossoides 2 Occasional 41-60 %
Phycodrys rubens 3 Frequent 41-60 %
Brongniartella byssoides 2 Occasional 41-60 %
Dictyota dichotoma 3 Frequent 61-80 %
Laminaria hyperborea 13 Common 81-100 %

Similar biotopes or habitat types

On very exposed coasts subject to weaker tidal currents. The fauna turf is characterised by a higher abundance of anthozoans such as Corynactis viridis and Sargartia elegans, but topshells such Calliostoma zizyphinum and Gibbula cineraria are also common. Red seaweeds are present but less dense than LhypT.Ft.

Occurs under similar wave exposure and tidal stream conditions, but on mixed substrata.


IR.MIR.KR.LhypT Laminaria hyperborea on tide-swept, infralittoral rock, Meikle Spiker, Dunbar. Paul Brazier © JNCC
IR.MIR.KR.LhypT Laminaria hyperborea on tide-swept, infralittoral rock, Meikle Spiker, Dunbar. Paul Brazier © JNCC

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