Description of biotope or habitat type
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Osmundea pinnatifida on moderately exposed mid eulittoral rock
Physical habitat 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.
- 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 |
|---|---|---|---|
| Osmundea pinnatifida | 41 | Abundant | 81-100% |
| Littorina littorea | 11 | Common | 61-80% |
| Semibalanus balanoides | 9 | Frequent | 61-80% |
| Corallinaceae | 6 | Occasional | 61-80% |
| Patella vulgata | 6 | Frequent | 41-60% |
| Mytilus edulis | 4 | Occasional | 41-60% |
| Nucella lapillus | 4 | Occasional | 41-60% |
| Fucus serratus | 3 | Occasional | 41-60% |
| Mastocarpus stellatus | 3 | Occasional | 41-60% |
| Actinia equina | 2 | Frequent | 21-40% |
| Corallina officinalis | 2 | Occasional | 41-60% |
| Littorina saxatilis | 2 | Occasional | 41-60% |
Similar biotopes or habitat types
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 perlevis can be present in LR.HLR.LR.LLR.FR.Coff. C. officinalis (Abundant) dominates instead of O. pinnatifida (Frequent ).
LR.HLR.MusB.Sem
Occurs in the mid eulittoral zone above LR.HLR.FR.Osm. It has a similar species composition, but lacks the red algae community.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1996 (6.95) | MLR.R.Osm |
| 1995 | LRK.RED.LAU |
Photos
