Description of biotope or habitat type
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Circalittoral mussel beds on rock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed |
| Tidal streams | Strong (3-6 kn), Moderately strong (1-3 kn) |
| Substratum | Bedrock |
| Zone | Circalittoral - upper, Circalittoral |
| Depth Band | 5-10 m, 10-20 m |
| 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'
- Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat
Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.
Description
This biotope complex occurs on moderately wave-exposed upper circalittoral bedrock subject to strong or moderately strong tidal streams. This complex is characterised by dense aggregations of the mussels Mytilus edulis or Musculus discors carpeting the underlying substrata. Sponges that may be recorded in this complex are Sycon ciliatum, Tethya aurantium, Pachymatisma johnstonia, Dysidea fragilis and Cliona celata. A sparse hydroid/bryozoan turf composed primarily of Nemertesia antennina, Alcyonidium diaphanum and Flustra foliacea is often recorded. Anemones present are Urticina felina and Cylista elegans. Other species recorded are the crabs Cancer pagurus, Carcinus maenas and Necora puber, the starfish Crossaster papposus and Asterias rubens, and Alcyonium digitatum. In this upper circalittoral complex, algae species such as Dictyota dichotoma, Cryptopleura ramosa and Plocamium cartilagineum. Two biotopes have been identified: CMyt (M. edulis dominated) and Mdis (M. discors dominated).
Situation
No situation data available.
Temporal variation
No temporal variation data available.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Mytilus edulis | 18 | Abundant | 41-60% |
| Asterias rubens | 15 | Frequent | 61-80% |
| Musculus discors | 13 | Super abundant | 41-60% |
| Urticina felina | 6 | Occasional | 41-60% |
| Cancer pagurus | 4 | Occasional | 41-60% |
| Flustra foliacea | 4 | Occasional | 41-60% |
| Cylista elegans | 3 | Occasional | 41-60% |
| Balanus crenatus | 2 | Frequent | 21-40% |
| Crossaster papposus | 2 | Occasional | 21-40% |
| Necora puber | 2 | Rare | 21-40% |
| Nemertesia antennina | 2 | Occasional | 21-40% |
| Pachymatisma johnstonia | 2 | Occasional | 21-40% |
| Sycon ciliatum | 2 | Occasional | 21-40% |
| Tethya aurantium | 2 | Occasional | 21-40% |
| Alcyonidium diaphanum | 1 | Frequent | 21-40% |
| Alcyonium digitatum | 1 | Occasional | 21-40% |
| Carcinus maenas | 1 | Common | 1-20% |
| Cliona celata | 1 | Rare | 21-40% |
| Cryptopleura ramosa | 1 | Frequent | 21-40% |
| Dictyota dichotoma | 1 | Frequent | 21-40% |
| Dysidea fragilis | 1 | Occasional | 21-40% |
| Plocamium cartilagineum | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
Not applicable or unknown.