Description of biotope or habitat type
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Semibalanus balanoides, Patella vulgata and Littorina spp. on exposed to moderately exposed or vertical sheltered eulittoral rock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Very exposed, Exposed, Moderately exposed |
| Tidal streams | |
| Substratum | Bedrock; large boulders |
| Zone | Eulittoral - mid, Eulittoral - upper |
| Depth Band | Mid shore, Upper shore |
| Other Features | Also on sheltered vertical bedrock |
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
Very exposed to sheltered mid to upper eulittoral bedrock and large boulders characterised by dense barnacles Semibalanus balanoides and the limpet Patella vulgata. The community has a relatively low diversity of species though occasional cracks and crevices in the rock can provide a refuge for small individuals of the mussel Mytilus edulis, the winkle Littorina spp. and the whelk Nucella lapillus. Seaweeds are usually not found in high numbers though fissures and crevices in the bedrock can hold a sparse algae community, though patches of the red seaweed Osmundea pinnatifida can be present throughout the zone. On some shores the olive green lichen Verrucaria mucosa can be present in some abundance (Frequent). Records should not be assigned to this species impoverished biotope if there is a significant number or abundance of seaweeds.
Situation
On very exposed to exposed shores Chthamalus spp. (see Cht.Cht for geographical variation) often forms a distinct white band above a darker band of S. balanoides in the mid eulittoral zone. Alternatively, found above Sem are the black lichen Verrucaria maura dominated biotopes (Ver.Ver or Ver.B). In the lower eulittoral and the sublittoral fringe is a community dominated by the wrack Himanthalia elongata and various red seaweeds including Corallina officinalis, Mastocarpus stellatus and Osmundea pinnatifida (Him; Coff; Osm) or the mussel and barnacle dominated biotope MytB. Sem.Sem may occur on steep and vertical faces on more sheltered shores, while fucoids dominate the flatter areas (Sem.FvesR; FvesB).
Temporal variation
Periods with little scour or less severe storms can allow a seaweed community to develop creating a more diverse biotope (i.e. Fves). This is a dynamic process, which will change individual sites over time. More information is required to validate this hypothesis.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Semibalanus balanoides | 35 | Common | 81-100% |
| Patella vulgata | 32 | Common | 61-80% |
| Mytilus edulis | 9 | Occasional | 61-80% |
| Nucella lapillus | 4 | Frequent | 41-60% |
| Verrucaria mucosa | 2 | Frequent | 21-40% |
| Ulva intestinalis | 2 | Occasional | 21-40% |
Similar biotopes or habitat types
LR.HLR.MusB.Sem.FvesR
Occurs on slightly less exposed shores. It has a higher abundance of S. balanoides (Abundant) and has a sparse seaweed community. The anemone Actinia equina is usually present in cracks and crevices.
LR.HLR.MusB.Cht.Cht
Usually occurs above LR.HLR.MusB.Sem in the upper eulittoral zone. It is dominated by the barnacles Chthamalus spp. which often are favoured on very exposed shores. S. balanoides can still be present in significant numbers.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | ELR.BPat.Sem |
