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Marine Habitat Classification


Description of biotope or habitat type

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   Osmundea pinnatifida on moderately exposed mid eulittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed
Tidal streams
Substratum Bedrock; boulders
Zone Eulittoral - mid
Depth Band
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 LR.HLR.FR.Osm <I>Osmundea pinnatifida</I> on moderately exposed mid 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 to moderately exposed lower eulittoral rock characterised by extensive areas or a distinct band of Osmundea pinnatifida and Gelidium pusillum (either together or separately). This community usually occurs on shores on which a fucoid canopy is reduced in extent, or even absent. Other turf-forming red seaweeds, such as Corallina officinalis, Mastocarpus stellatus, Ceramium spp. and Callithamnion hookeri may be present, although O. pinnatifida always dominate. On flatter, more sheltered shores, Osmundea hybrida may also occur. Small patches of bare rock amongst the algal turf are occupied by barnacles Semibalanus balanoides, the limpet Patella vulgata, the whelk Nucella lapillus and small individuals of the mussel Mytilus edulis. The winkles Littorina littorea and Littorina saxatilis can be present on the rock or among the seaweeds. A variation of this biotope has been described for the chalk platforms in Kent where extensive turfs of G. pusillum occur in the mid eulittoral above the main O. pinnatifida zone.

Situation

This biotope can be found below barnacles S. balanoides or red seaweed dominated community, which includes the species Palmaria palmata, C. officinalis or M. stellatus (Sem; Coff; Cor). It is found above biotopes dominated by the wrack Fucus serratus and red seaweeds (FcdR; MytFR; Fser.R) or above biotopes dominated by the kelp Laminaria digitata (Ldig.Ldig).

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
Actinia equina 2 Frequent 21-40 %
Semibalanus balanoides 9 Frequent 61-80 %
Patella vulgata 6 Frequent 41-60 %
Littorina littorea 11 Common 61-80 %
Littorina saxatilis 2 Occasional 41-60 %
Nucella lapillus 4 Occasional 41-60 %
Mytilus edulis 4 Occasional 41-60 %
Corallinaceae 6 Occasional 61-80 %
Corallina officinalis 2 Occasional 41-60 %
Osmundea pinnatifida 41 Abundant 81-100 %
Mastocarpus stellatus (petrocelis) 3 Occasional 41-60 %
Fucus serratus 3 Occasional 41-60 %

Similar biotopes

LR.HLR.FR.Coff
Occurs in the lower eulittoral zone, but in otherwise similar physical conditions. The same species can occur in both biotopes although sponges such as Halichondria panicea and Hymeniacidon perleve can be present in Coff. C. officinalis (Abundant) dominates instead of O. pinnatifida (Frequent ).

LR.HLR.MusB.Sem
Occurs in the mid eulittoral zone above Osm. It has a similar species composition, but lacks the red algae community.

Biotope history

Classification Habitat code
6.95 LRK.RED.LAU
96.7 MLR.R.Osm

Photos

LR.HLR.FR.Osm Osmundea pinnatifida on moderately exposed mid eulittoral rock, St. Margarets Bay, South Foreland, Dover. David George © JNCC
LR.HLR.FR.Osm Osmundea pinnatifida on moderately exposed mid eulittoral rock, St. Margarets Bay, South Foreland, Dover. David George © JNCC
LR.HLR.FR.Osm Osmundea pinnatifida on moderately exposed mid eulittoral rock, Friars Bay. Keith Hiscock © JNCC
LR.HLR.FR.Osm Osmundea pinnatifida on moderately exposed mid eulittoral rock, Friars Bay. Keith Hiscock © JNCC
LR.HLR.FR.Osm Osmundea pinnatifida on moderately exposed mid eulittoral rock, Kingsgate-Botany Bay, Thanet. David George © JNCC
LR.HLR.FR.Osm Osmundea pinnatifida on moderately exposed mid eulittoral rock, Kingsgate-Botany Bay, Thanet. David George © JNCC

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