Description of biotope or habitat type
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Polyides rotunda, Ahnfeltia plicata and Chondrus crispus on sand-covered infralittoral rock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Exposed, Moderately exposed |
| Tidal streams | Moderately strong (1-3 kn), Weak (>1 kn) |
| Substratum | Bedrock, cobbles and pebbles with mobile sand |
| Zone | Infralittoral |
| Depth Band | 5-10 m |
| Other Features | Sand-covered rock |
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
Low-lying rock surrounded by mobile sand and often subject to burying by the sand, with a turf of resilient red seaweeds Chondrus crispus, Polyides rotunda and Ahnfeltia plicata typically protruding through the sand on the upper surfaces of the rock. Other scour-tolerant seaweeds include Rhodomela confervoides, Phyllophora pseudoceranoïdes, Phyllophora crispa, Furcellaria lumbricalis, Gracilaria gracilis, Ceramium rubrum, Plocamium cartilagineum, Heterosiphonia plumosa, Cryptopleura ramosa and Dilsea carnosa. Coralline crusts typically cover the rock, while scattered individuals of the brown seaweeds Halidrys siliquosa, Cladostephus spongiosus, Dictyota dichotoma and Saccharina latissima can be present. The large anthozoan Urticina felina can occur in this biotope but there are few other conspicuous animals.
Situation
This biotope occurs on shallow sand-covered rock, often below bedrock and boulders supporting kelp forest, which is above the effect of, sand scour (Lhyp) or abutting sand-scoured kelp on bedrock (XKScrR). It may also be found adjacent to the shallow kelp and Chorda filum biotope (LsacChoR) and similarly can be surrounded by a variety of sediment biotopes.
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 |
|---|---|---|---|
| Chondrus crispus | 15 | Frequent | 81-100% |
| Polyides rotunda | 10 | Frequent | 61-80% |
| Corallinaceae | 9 | Frequent | 61-80% |
| Ahnfeltia plicata | 6 | Frequent | 41-60% |
| Dilsea carnosa | 6 | Occasional | 41-60% |
| Furcellaria lumbricalis | 4 | Occasional | 41-60% |
| Saccharina latissima | 4 | Occasional | 41-60% |
| Cryptopleura ramosa | 3 | Occasional | 41-60% |
| Heterosiphonia plumosa | 3 | Frequent | 41-60% |
| Phyllophora crispa | 3 | Occasional | 41-60% |
| Phyllophora pseudoceranoides | 3 | Frequent | 41-60% |
| Rhodomela confervoides | 3 | Frequent | 41-60% |
| Dictyota dichotoma | 2 | Occasional | 21-40% |
| Plocamium cartilagineum | 2 | Occasional | 41-60% |
| Ceramium nodulosum | 1 | Frequent | 21-40% |
| Cladostephus spongiosus | 1 | Occasional | 21-40% |
| Gracilaria gracilis | 1 | Frequent | 21-40% |
| Halidrys siliquosa | 1 | Occasional | 21-40% |
| Urticina felina | 1 | Occasional | 21-40% |
| Ulva | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
IR.HIR.KSed.XKHal
Lack of large boulders or prominent bedrock in IR.HIR.KSed.ProtAhn prevents dominance by H. siliquosa or kelps.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 2015 (15.03) | IR.HIR.KSed.ProtAhn |
| 1997 (97.06) | MIR.PolAhn |