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Marine Habitat Classification


Description of biotope or habitat type

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   Semibalanus balanoides, Fucus vesiculosus and red seaweeds on exposed to moderately exposed eulittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed
Tidal streams
Substratum Bedrock
Zone Eulittoral - mid, Eulittoral - upper
Depth Band Mid shore
Other Features The growth formFucus vesiculosus f. linearis is often present

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 LR.HLR.MusB.Sem.FvesR <I>Semibalanus balanoides</I>, <I>Fucus vesiculosus</I> and red seaweeds on exposed to moderately exposed eulittoral 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'

Point data based on records in the UK Marine Recorder Snapshot.

Description

Exposed and moderately exposed upper and mid eulittoral bedrock characterised by the barnacle Semibalanus balanoides, the limpet Patella vulgata and the whelk Nucella lapillus with a sparse community of seaweeds. Turfs of the wrack Fucus vesiculosus can be present on the more horizontal parts of the shore though usually in low abundance (Occasional). Individuals of F. vesiculosus can lack the characteristic twin air bladders due to environmental stress (i.e. wave exposure). A sparse seaweed community consisting of foliose red seaweeds such as Osmundea pinnatifida and Mastocarpus stellatus are usually present along with the Corallina officinalis and the green seaweed Enteromorpha intestinalis. The algal community is usually restricted to fissures and cracks in the bedrock surface. Moist cracks and crevices also provide a refuge for small individuals of the mussel Mytilus edulis and the winkles Littorina saxatilis and Littorina littorea. These crevices can also be occupied by encrusting coralline algae and the anemone Actinia equina.

Situation

On exposed and moderately exposed shores Sem.FvesR is found below the black lichen Verrucaria maura and sparse barnacles biotope (Ver.B) and/or below the Chthamalus spp. and P. vulgata biotopes (Cht). Sem.FvesR is found above the biotope dominated by the wrack Himanthalia elongata (Him) or the red seaweed biotopes (Coff).

Temporal variation

On some shores, particularly those which are moderately exposed to wave action, temporal fluctuations in the abundance of limpets, barnacles and fucoid seaweeds may occur. As a result, over a number of years, a single shore may cycle between the barnacle-P. vulgata dominated biotope (Sem.FvesR) and a F. vesiculosus-dominated biotope (Fves). Individuals of F. vesiculosus growing in stressed environmental conditions (i.e. high wave exposure) do not always develop the characteristic twin air bladders.

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Actinia equina 4 Occasional 61-80 %
Semibalanus balanoides 27 Abundant 81-100 %
Patella vulgata 19 Abundant 81-100 %
Littorina 8 Frequent 21-40 %
Littorina littorea 2 Occasional 41-60 %
Littorina saxatilis 2 Occasional 41-60 %
Nucella lapillus 3 Frequent 61-80 %
Mytilus edulis 6 Occasional 61-80 %
Corallinaceae 4 Occasional 61-80 %
Corallina officinalis 2 Occasional 41-60 %
Mastocarpus stellatus 2 Occasional 41-60 %
Osmundea pinnatifida 3 Occasional 61-80 %
Fucus vesiculosus 4 Occasional 61-80 %
Enteromorpha intestinalis 4 Occasional 61-80 %

Similar biotopes

LR.HLR.MusB.Cht
Occurs in the upper eulittoral zone on slightly more exposed shores. It is dominated by the barnacles Chthamalus spp. and has a lower abundance of S. balanoides and N. lapillus. It lacks the sparse flora of seaweeds that are characteristic of Sem.FvesR.

Biotope history

Classification Habitat code
97.06 MLR.BPat.Fvesl

Photos

LR.HLR.MUSB.Sem.FvesR Semibalanus balanoides, Fucus vesiculosus and red seaweeds on exposed to moderately exposed eulittoral rock, S of Rosemullion Head, Helford River. Keith Hiscock © JNCC
LR.HLR.MUSB.Sem.FvesR Semibalanus balanoides, Fucus vesiculosus and red seaweeds on exposed to moderately exposed eulittoral rock, S of Rosemullion Head, Helford River. Keith Hiscock © JNCC
LR.HLR.MUSB.Sem.FvesR Semibalanus balanoides, Fucus vesiculosus and red seaweeds on exposed to moderately exposed eulittoral rock, Tarn Bay, Ravenglass. Roger Covey © JNCC
LR.HLR.MUSB.Sem.FvesR Semibalanus balanoides, Fucus vesiculosus and red seaweeds on exposed to moderately exposed eulittoral rock, Tarn Bay, Ravenglass. Roger Covey © JNCC

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