Description of biotope or habitat type
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Corynactis viridis and a mixed turf of crisiids, Bugula, Scrupocellaria, and Cellaria on moderately tide-swept exposed circalittoral rock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Very exposed, Exposed, Moderately exposed |
| Tidal streams | Strong (3-6 kn), Moderately strong (1-3 kn) |
| Substratum | Bedrock; very large boulders |
| Zone | Circalittoral - lower, Circalittoral - upper |
| Depth Band | 10-20 m, 20-30 m |
| Other Features | Often on vertical or steep 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
This biotope typically occurs on wave-exposed, vertical or steep, circalittoral bedrock or large boulders, usually subject to moderate or strong tidal streams. It is characterised by dense aggregations of the anemone Corynactis viridis and the cup coral Caryophyllia smithii intermixed with a short bryozoan turf of one or more Crisia spp., Scrupocellaria spp., Bugula spp. and Cellaria spp. Occasionally, this turf obscures the underlying C. virdis and C. smithii. Cushion and encrusting sponges, particularly Pachymatisma johnstonia, Cliona celata, Amphilectus fucorum and Dysidea fragilis, are present in moderate amounts at many sites. The axinellid sponges Stelligera spp. and Raspailia spp. are less frequently recorded. Clumps of large hydroids such as Nemertesia antennina and Nemertesia ramosa as well as the soft coral Alcyonium digitatum and the bryozoan Alcyonidium diaphanum may be found covering the hard substratum. The anemones Actinothoe sphyrodeta and Cylista elegans are typically present in low numbers, while the hard `coral' Pentapora foliacea is also occasionally observed. The most frequently recorded echinoderms are Marthasterias glacialis and Asterias rubens, although other species such as Echinus esculentus may also be seen. The rocky substratum may have a patchy covering of encrusting red seaweeds/algae. The crabs Necora puber and Cancer pagurus may be seen in crevices or under overhangs. This biotope is regularly recorded around south west England and Wales, often on vertical rock faces.
Situation
Due to its wave-exposed nature, kelp park and forest biotopes (LhypR and Ala) are commonly found in the infralittoral zone shallower than this biotope, and feature species such as Laminaria hyperborea, Sacchoriza polyschides and Alaria esculenta.
Temporal variation
Not known.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Alcyonium digitatum | 10 | Common | 81-100% |
| Corynactis viridis | 9 | Common | 81-100% |
| Caryophyllia smithii | 8 | Frequent | 81-100% |
| Cliona celata | 5 | Occasional | 81-100% |
| Asterias rubens | 4 | Frequent | 61-80% |
| Crisiidae | 4 | Common | 61-80% |
| Marthasterias glacialis | 4 | Frequent | 81-100% |
| Actinothoe sphyrodeta | 3 | Occasional | 61-80% |
| Bryozoa | 3 | Frequent | 61-80% |
| Nemertesia antennina | 3 | Common | 61-80% |
| Alcyonidium diaphanum | 2 | Occasional | 41-60% |
| Dysidea fragilis | 2 | Occasional | 41-60% |
| Necora puber | 2 | Occasional | 61-80% |
| Nemertesia ramosa | 2 | Occasional | 41-60% |
| Pachymatisma johnstonia | 2 | Occasional | 61-80% |
| Pentapora foliacea | 2 | Occasional | 41-60% |
| Echinus esculentus | 2 | Occasional | 61-80% |
| Corallinaceae | 1 | Occasional | 41-60% |
| Porifera | 1 | Occasional | 41-60% |
| Cancer pagurus | 1 | Rare | 41-60% |
| Cellaria sinuosa | 1 | Frequent | 21-40% |
| Amphilectus fucorum | 1 | Occasional | 41-60% |
| Raspailia ramosa | 1 | Occasional | 41-60% |
| Cylista elegans | 1 | Occasional | 41-60% |
| Scrupocellaria | 1 | Common | 21-40% |
Similar biotopes or habitat types
CR.HCR.XFa.ByErSp.Cyl
This variant is found on slightly less exposed coasts and in slightly weaker tides than CR.HCR.XFa.CvirCri. In addition, CR.HCR.XFa.ByErSp.Cyl is characterised by a greater diversity of sponges, hydroids and anemones and also has small amounts of polyclinid ascidians, which in CR.HCR.XFa.CvirCri are rare. CR.HCR.XFa.ByErSp.Cyl may sometimes be found below CR.HCR.XFa.CvirCri.
CR.MCR.EcCr.CarSp.PenPcom
This variant is subject to weaker tides than CR.HCR.XFa.CvirCri, but is found on similar wave-exposed upward-facing bedrock. The general appearance of CR.MCR.EcCr.CarSp.PenPcom is of a fairly sparse but diverse fauna and it lacks the bryozoan turf of CR.HCR.XFa.CvirCri, having larger amounts of brittle and encrusting bryozoans such as Porella compressa and Parasmittina trispinosa.
CR.HCR.XFa.ByErSp.Eun
This variant occurs under similar conditions as CR.HCR.XFa.CvirCri. It is characterised by the presence of Eunicella verrucosa and Alcyonium glomeratum, in combination with diverse sponges and hydroids. It also contains a much wider range of ascidians than CR.HCR.XFa.CvirCri.
CR.HCR.XFa.ByErSp.DysAct
This sub-biotope occurs on similar wave-exposed bedrock and boulders as CR.HCR.XFa.CvirCri, but is found in slightly stronger tidal streams. The sponge D. fragilis and the anemone A. sphyrodeta are present in much higher abundances than in CR.HCR.XFa.CvirCri. A more diverse range of ascidians is present in CR.HCR.XFa.ByErSp.DysAct.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | CR.ECR.EFa.CorCri |
Photos
