Description of biotope or habitat type
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Verrucaria mucosa and/or Hildenbrandia rubra on upper to mid shore cave walls
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Exposed, Moderately exposed |
| Tidal streams | |
| Substratum | Bedrock |
| Zone | Eulittoral - mid, Eulittoral - upper, Littoral fringe |
| Depth Band | |
| Other Features | Moist, dark caves |
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
The upper walls and ceilings of the entrances and inner reaches of upper shore caves affected by direct wave action (and therefore moistened by sea spray), characterised by a mosaic of the olive green lichen Verrucaria mucosa and the non-calcified encrusting red alga Hildenbrandia rubra. The black lichen Verrucaria maura and red coralline algae can be present, though not dominating. The fauna in these upper shore caves is generally limited, due to problems of desiccation. However, where conditions remain sufficiently moist, and particularly in crevices and fissures, the barnacle Semibalanus balanoides, the limpet Patella vulgata and winkles Littorina saxatilis may occur, particularly towards the rear of the cave. Although the characterising species of this biotope also occur on the shore, they do not generally occur in a distinct band other than in moist dark caves. The turf-forming red seaweed Rhodochorton purpureum may occasionally occur in low abundance (where A. purpurea covers an extensive area, generally on softer rock such as chalk, the biotope should be recorded as AudCla).
Situation
VmucHil generally occurs on upper walls and ceilings towards the rear of dark, moist caves, but can also occur at cave entrances that are directly affected by sea-spray. Where VmucHil occurs at cave entrances and to approximately 5 m into the cave, it is usually found above a zone of Sem and below GCv or AudCla. Further into the cave Sem is replaced completely by VmucHil. There are no records for VmucHil in soft rock caves.
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 |
|---|---|---|---|
| Verrucaria mucosa | 38 | Abundant | 61-80% |
| Hildenbrandia rubra | 30 | Super abundant | 61-80% |
| Patella vulgata | 13 | Common | 61-80% |
| Verrucaria maura | 8 | Common | 41-60% |
| Corallinaceae | 2 | Occasional | 21-40% |
| Semibalanus balanoides | 1 | Occasional | 21-40% |
| Rhodochorton purpureum | 1 | Frequent | 21-40% |
| Littorina saxatilis | 1 | Occasional | 21-40% |
Similar biotopes or habitat types