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Marine Habitat Classification


Description of biotope or habitat type

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   Grazed, mixed Laminaria hyperborea and Laminaria saccharina on sheltered infralittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Sheltered, Very sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Bedrock & boulders
Zone Infralittoral - upper
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.LIR.K.LhypLsac.Gz Grazed, mixed <I>Laminaria hyperborea</I> and <I>Laminaria saccharina</I> 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

Silted infralittoral rock with mixed Laminaria hyperborea and Laminaria saccharina kelp forest, intensively grazed by the echinoderm Echinus esculentus and the gastropods Gibbula cineraria and Calliostoma zizyphinum. Although both kelp species can occur in equal abundance (Common), L. hyperborea usually dominates. The grazing-resistant brown seaweed Desmarestia aculeata and Cutleria multifida may be present. A similar variety of red seaweeds to those found in the ungrazed kelp forest (LhypLsac.Ft) may occur beneath the kelp canopy, but in much lower abundance. As grazing intensity increases the seaweed cover decreases - and some sites are reduced to the bare appearance of encrusting brown and coralline algae beneath the kelp canopy. The L. hyperborea stipes generally support more seaweeds than the rock beneath, including Cryptopleura ramosa, Delesseria sanguinea, Phycodrys rubens and Bonnemaisonia hamifera. The stipes may also support sometimes dense ascidians Clavelina lepadiformis and Ciona intestinalis and the echinoderm Antedon bifida. The kelp fronds are often densely covered by the hydroid Obelia geniculata. At the most intensively grazed sites even the kelp stipes are bare. Although the rock appears bare, between boulders and in crevices there are often the brittlestar Ophiothrix fragilis and the crabs Necora puber and Pagurus bernhardus. The tube-building Pomatoceros triqueter and bryozoan crusts are commonly found on any vertical surfaces.

Situation

This biotope can be found in similar conditions as LhypLsac.Ft and LhypLsac.Pk but where the numbers of grazers present are in high enough numbers to cause substantially community impoverishment through grazing. Generally occurs on isolated rock, surrounded by sediment biotopes. Although it has been recorded from sites astride the ungrazed kelp biotopes (LhypLsac.Ft and LhypLsac.Pk) it is more usually found on bedrock or boulder exposures (XFa) adjacent to sediment seabed characterised by infaunal species.

Temporal variation

If the grazing pressure is reduced (i.e. a decrease in the number of grazing echinoderms present) the community will eventually re-establish itself as a mixed kelp forest or park (LhypLsac).

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Obelia geniculata 1 Occasional 41-60 %
Pomatoceros triqueter 7 Frequent 61-80 %
Pagurus bernhardus 2 Occasional 41-60 %
Necora puber 1 Occasional 41-60 %
Gibbula cineraria 5 Frequent 61-80 %
Calliostoma zizyphinum 2 Occasional 41-60 %
Antedon bifida 1 Occasional 21-40 %
Asterias rubens 6 Occasional 61-80 %
Ophiothrix fragilis 2 Occasional 41-60 %
Echinus esculentus 10 Frequent 81-100 %
Clavelina lepadiformis 1 Occasional 41-60 %
Bonnemaisonia hamifera 1 Occasional 21-40 %
Corallinaceae 7 Abundant 61-80 %
Cryptopleura ramosa 1 Frequent 21-40 %
Delesseria sanguinea 2 Occasional 41-60 %
Phycodrys rubens 2 Frequent 41-60 %
Cutleria multifida 4 Frequent 41-60 %
Desmarestia aculeata 2 Frequent 41-60 %
Laminaria hyperborea 14 Common 81-100 %
Laminaria saccharina 7 Common 61-80 %

Similar biotopes

IR.MIR.KR.Lhyp.GzFt
Found in more wave-exposed conditions, it has a greater range of sponges, hydroids and colonial ascidians. L. hyperborea is typically dense (Abundant) with L. saccharina (Occasional). NB notice the few records for this biotope.

IR.LIR.K.LhypLsac.Ft
Has a greater abundance of foliose red seaweeds and fewer grazing echinoderms with a high abundance of the kelp L. hyperborea (Abundant) and L. saccharina (Abundant).


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