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Marine Habitat Classification


Description of biotope or habitat type

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   Grazed Laminaria saccharina with Echinus, brittlestars and coralline crusts on sheltered infralittoral rock


Habitat (physical) description

Salinity Variable (18-35 ppt)
Wave exposure Very sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Bedrock & boulders
Zone Infralittoral - upper, 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.K.Lsac.Gz Grazed <I>Laminaria saccharina</I> with <I>Echinus</I>, brittlestars and coralline crusts on sheltered 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.

Description

Coralline encrusted rock with scattered tufts of red seaweed and a relatively high abundance of grazing echinoderms which typically include the urchin Echinus esculentus and/or the brittlestars Ophiothrix fragilis or Ophiocomina nigra. The rock often looks bare, with few conspicuous species present although Laminaria saccharina may occur it is generally in low abundance (Rare or Occasional). The red seaweeds, reduced to small tufts through grazing, include Phycodrys rubens, Delesseria sanguinea and Brongniartella byssoides and although these seaweeds also occur in Lsac.Pk they are far less frequent in this biotope. Brown seaweeds, such as Desmarestia viridis, Chorda filum and Cutleria multifida, may be present. Grazing molluscs, such as Gibbula cineraria and can be common. Under-boulder habitats can harbour the crabs Necora puber and Pagurus bernhardus, terebellid polychaetes and the polychaete Pomatoceros spp. with ascidians Ascidia mentula. and Clavelina lepadiformis on the open rock along with the echinoderm Asterias rubens and the hydroids Kirchenpauria pinnata and Obelia dichotoma.

Situation

This biotope generally occurs on rock below a dense kelp forest of L. saccharina (Lsac.Ft) or mixed kelp (LhypLsac.Ft).

Temporal variation

If the grazing pressure is reduced (i.e. a decrease in the number of grazing echinoderms present) a richer kelp community may develop (Lsac.Pk or LhypLsac.Pk).

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Kirchenpaueria pinnata 3 41-60 %
Obelia dichotoma 2 21-40 %
Terebellidae 1 Rare 41-60 %
Pomatoceros 9 Frequent 41-60 %
Pagurus bernhardus 3 Occasional 41-60 %
Necora puber 2 Rare 41-60 %
Gibbula cineraria 5 Occasional 41-60 %
Asterias rubens 6 Occasional 61-80 %
Ophiothrix fragilis 4 Rare 41-60 %
Ophiocomina nigra 3 41-60 %
Echinus esculentus 11 Occasional 81-100 %
Ascidia mentula 3 41-60 %
Corallinaceae 12 Common 61-80 %
Delesseria sanguinea 2 21-40 %
Phycodrys rubens 4 Rare 41-60 %
Brongniartella byssoides 2 21-40 %
Filamentous red algae 1 21-40 %
Cutleria multifida 1 Frequent 21-40 %
Desmarestia viridis 1 Occasional 21-40 %
Chorda filum 2 41-60 %
Laminaria saccharina 12 Occasional 81-100 %

Similar biotopes

IR.LIR.K.Lsac.Pk
This biotope a higher diversity and abundance of red seaweeds. Lsac.Pk also have a notable presence of sponges (Porifera), which are usually absent in Lsac.Gz.

CR.MCR.EcCr.FaAlCr
Occurs in deeper more exposed sites and has a similar grazed crustose appearance but lacks the red and brown seaweeds of Lsac.Gz.


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