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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.

   Grazed Laminaria hyperborea park with coralline crusts on lower infralittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Bedrock; boulders
Zone Infralittoral - lower
Depth Band 10-20 m
Other Features Urchin grazing

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.Lhyp.GzPk Grazed <I>Laminaria hyperborea</I> park with coralline crusts on lower 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

Exposed to moderately exposed Laminaria hyperborea kelp park in some areas is intensively grazed by the urchin Echinus esculentus. The rock surface lacks a significant turf of foliose seaweeds and generally looks bare, though coralline algal crusts and some grazing-resistant animals such as the tube-building polychaete Pomatoceros triqueter cover it. The kelp stipes may or may not be grazed; in the most extremely grazed areas, the stipes are also devoid of seaweeds. More usually, however, the stipes offers a refuge from grazing, and are characterised by dense turfs of red seaweeds, especially Phycodrys rubens and Delesseria sanguinea. Brown seaweeds present include Cutleria multifida, Laminaria saccharina and Dictyota dichotoma. The fauna within a grazed kelp park is also relatively sparse, though some species will survive in cracks and crevices or under boulders including the ascidian Clavelina lepadiformis. The encrusting bryozoan Parasmittina trispinosa and the anthozoans Alcyonium digitatum, Urticina felina and Caryophyllia smithii often characterise vertical or overhanging rock. Mobile species include the gastropods Gibbula cineraria and Calliostoma zizyphinum and the hermit crab Pagurus bernhardus The echinoderms Ophiocomina nigra, Ophiothrix fragilis and Crossaster papposus, generally absent from the kelp forest, can be found in these kelp parks along with Asterias rubens and Antedon bifida.

Situation

This biotope generally occurs below a grazed kelp forest (Lhyp.GzFt) but can also occur below ungrazed kelp forests on exposed sites where wave action can dislodge urchins from shallow rock. The grazed circalittoral biotope FaAlCr often occurs on the bedrock or boulders below.

Temporal variation

Fluctuations in the numbers of E. esculentus may give foliose seaweeds a chance to re-grow periodically. Further information is required on the temporal variation within these grazed kelp parks and the changes in community structure when grazing pressure decreases.

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Alcyonium digitatum 3 Occasional 61-80 %
Urticina felina 2 Occasional 41-60 %
Caryophyllia smithii 1 Occasional 41-60 %
Pomatoceros triqueter 5 Frequent 61-80 %
Pagurus bernhardus 1 Occasional 21-40 %
Gibbula cineraria 4 Occasional 61-80 %
Calliostoma zizyphinum 3 Occasional 41-60 %
Parasmittina trispinosa 1 Occasional 41-60 %
Antedon bifida 3 Occasional 41-60 %
Crossaster papposus 1 Rare 41-60 %
Asterias rubens 5 Occasional 61-80 %
Ophiothrix fragilis 2 Occasional 41-60 %
Ophiocomina nigra 2 Occasional 21-40 %
Echinus esculentus 14 Common 81-100 %
Clavelina lepadiformis 2 Occasional 41-60 %
Corallinaceae 12 Abundant 81-100 %
Delesseria sanguinea 1 Occasional 41-60 %
Phycodrys rubens 3 Occasional 41-60 %
Cutleria multifida 4 Frequent 21-40 %
Dictyota dichotoma 2 Occasional 41-60 %
Laminaria hyperborea 9 Frequent 81-100 %
Laminaria saccharina 1 Occasional 21-40 %

Similar biotopes

IR.MIR.KR.Lhyp.GzFt
Found above the kelp park and has a higher abundance of kelps but similar species composition to the park (Lhyp.GzPk).

IR.HIR.KSed.XKScrR
Bare rock surfaces beneath the kelp canopy may also be caused by sand-scour and should not be confused with the barren appearance of a community decimated (reduced) by grazing.

Photos

IR.MIR.KR.Lhyp.GzPk Grazed Laminaria hyperborea park with coralline crusts on lower infralittoral rock, S of Skrowa Skerry, SW Mainland, Orkney. Keith Hiscock © JNCC
IR.MIR.KR.Lhyp.GzPk Grazed Laminaria hyperborea park with coralline crusts on lower infralittoral rock, S of Skrowa Skerry, SW Mainland, Orkney. Keith Hiscock © JNCC
IR.MIR.KR.Lhyp.GzPk Grazed Laminaria hyperborea park with coralline crusts on lower infralittoral rock, Headland near Geodh a' Bhodaich, Loch Ewe. Rohan Holt © JNCC
IR.MIR.KR.Lhyp.GzPk Grazed Laminaria hyperborea park with coralline crusts on lower infralittoral rock, Headland near Geodh a' Bhodaich, Loch Ewe. Rohan Holt © JNCC

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