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Marine Habitat Classification


Description of biotope or habitat type

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   Laminaria hyperborea forest with dense foliose red seaweeds on exposed upper infralittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Extremely exposed, Very exposed, Exposed
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn)
Substratum Bedrock; large 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.HIR.KFaR.LhypR.Ft <I>Laminaria hyperborea</I> forest with dense foliose red seaweeds on exposed upper 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

Very exposed to exposed upper infralittoral bedrock or large boulders characterised by a dense forest of the kelp Laminaria hyperborea. On the rock surface beneath the kelp canopy is a dense turf of red foliose seaweeds including Cryptopleura ramosa, Plocamium cartilagineum, Phycodrys rubens and Callophyllis laciniata as well as encrusting coralline algae and the foliose brown seaweed Dictyota dichotoma. The red algal turf can be virtually mono-specific, dominated by stands of P. cartilagineum, C. ramosa or Heterosiphonia plumosa, Kallymenia reniformis or in the north, Odonthalia dentata. Other sites may contain a dense mixed turf of these and other species. The dense turf is due, in part, to the relatively low grazing pressure from the urchin Echinus esculentus in such shallow exposed conditions. The shallowest kelp plants are often short or stunted, while deeper plants are taller and the stipes are heavily epiphytised by red seaweeds such as Delesseria sanguinea and Membranoptera alata. The bryozoan Electra pilosa can form colonies on the foliose red seaweeds, while the bryozoan Membranipora membranacea more often can be found on the L. hyperborea fronds along with the ascidian Botryllus schlosseri and the hydroid Obelia geniculata. The gastropods Gibbula cineraria and Calliostoma zizyphinum are found grazing among the kelp holdfasts, while a few individuals of the barnacle Balanus crenatus can present along with the white calcareous tubes of the polychaete Pomatoceros triqueter, where substratum is available. The starfish Asterias rubens can be found predating on polychaetes, mussels and small crustaceans. The soft coral Alcyonium digitatum can be present covering the rock surface as well as the anthozoan Urticina felina.

Situation

This kelp forest biotope most commonly occurs beneath a zone of Alaria esculenta/Mytilus edulis (Ala.Myt) and above a L. hyperborea park (LhypR.Pk). At very exposed sites, such as some areas of Shetland and St Kilda, the lower infralittoral zone is often characterised by a park of Laminaria saccharina and/or Saccorhiza polyschides (LsacSac). This zone presumably develops due to the mobility of nearby cobbles, boulders and sediment during winter storms, removing the slower growing L. hyperborea. Occasionally, a band of dense foliose seaweeds, with no kelp, occurs below the kelp forest (FoR or FoR.Dic).

Temporal variation

Unknown.

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 Frequent 21-40 %
Alcyonium digitatum 1 Occasional 41-60 %
Urticina felina 1 Occasional 41-60 %
Pomatoceros triqueter 1 Frequent 61-80 %
Balanus crenatus 1 Frequent 21-40 %
Gibbula cineraria 1 Occasional 41-60 %
Calliostoma zizyphinum 1 Occasional 41-60 %
Membranipora membranacea 2 Frequent 41-60 %
Electra pilosa 2 Frequent 41-60 %
Asterias rubens 2 Occasional 41-60 %
Echinus esculentus 2 Frequent 41-60 %
Botryllus schlosseri 2 Occasional 41-60 %
Corallinaceae 5 Frequent 61-80 %
Callophyllis laciniata 3 Frequent 61-80 %
Kallymenia reniformis 1 Occasional 61-80 %
Plocamium cartilagineum 5 Frequent 61-80 %
Heterosiphonia plumosa 1 Frequent 41-60 %
Cryptopleura ramosa 6 Frequent 61-80 %
Delesseria sanguinea 6 Frequent 81-100 %
Hypoglossum hypoglossoides 1 Occasional 41-60 %
Membranoptera alata 2 Occasional 41-60 %
Phycodrys rubens 4 Frequent 61-80 %
Dictyota dichotoma 4 Frequent 61-80 %
Laminaria hyperborea 18 Abundant 81-100 %

Similar biotopes

IR.HIR.KFaR.LhypFa
Occurs in areas with more wave-surge. The cushion fauna in this biotope is markedly more abundant than kelp forests in areas with less wave surge.

Photos

IR.HIR.KFAR.LhypR.Ft Laminaria hyperborea forest with dense foliose red seaweeds on exposed upper infralittoral rock, S of Skrowa Skerry, SW Mainland, Orkney. Sheila Woodman © JNCC
IR.HIR.KFAR.LhypR.Ft Laminaria hyperborea forest with dense foliose red seaweeds on exposed upper infralittoral rock, S of Skrowa Skerry, SW Mainland, Orkney. Sheila Woodman © JNCC

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