Description of biotope or habitat type
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Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Extremely exposed, Very exposed, Exposed, Moderately exposed |
| Tidal streams | Moderately strong (1-3 kn) |
| Substratum | Bedrock |
| Zone | Circalittoral - lower, Circalittoral - upper |
| Depth Band | 10-20 m, 20-30 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 variant typically occurs on wave-exposed, steep, circalittoral bedrock, boulder slopes and outcrops, subject to varying tidal streams. This silty variant contains a diverse faunal community, dominated by the seafan Eunicella verrucosa, the bryozoan Pentapora foliacea and the cup coral Caryophyllia smithii. There are frequently numerous Alcyonium digitatum, and these may become locally abundant under more tide-swept conditions. Alcyonium glomeratum may also be present. A diverse sponge community is usually present, including numerous erect sponges; species present include Cliona celata, Raspailia ramosa, Raspailia (Clathriodendron) hispida, Axinella dissimilis, Stelligera stuposa, Dysidea fragilis and Polymastia boletiformis. Homaxinella subdola may be present in the south west. A hydroid/bryozoan turf may develop in the understorey of this rich sponge assemblage, with species such as Nemertesia antennina, Nemertesia ramosa, crisiids, Alcyonidium diaphanum and Crisularia plumosa. The sea cucumber Holothuria (Panningothuria) forskali may be locally abundant, feeding on the silty deposits on the rock surface. Other echinoderms encountered include the starfish Marthasterias glacialis and the urchin Echinus esculentus. Other fauna includes aggregations of colonial ascidians Clavelina lepadiformis and Stolonica socialis. Anemones such as Actinothoe sphyrodeta and Parazoanthus axinellae may be seen dotted across the rock surface. This biotope is present in south west England and Wales.
Situation
This biotope is commonly found on rocky outcrops, surrounded by coarse sediment. This may be in the form of shelly gravel or muddy gravel, supporting Urticina felina, Cerianthus lloydi and Neopentadactyla mixta. Above ByErSp.Eun, dense kelp forest containing Saccorhiza polyschides is usually found.
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 |
|---|---|---|---|
| Eunicella verrucosa | 7 | Frequent | 81-100% |
| Caryophyllia smithii | 7 | Common | 81-100% |
| Pentapora foliacea | 7 | Frequent | 81-100% |
| Alcyonium digitatum | 6 | Frequent | 81-100% |
| Cliona celata | 5 | Frequent | 81-100% |
| Nemertesia antennina | 5 | Frequent | 81-100% |
| Alcyonidium diaphanum | 4 | Frequent | 61-80% |
| Marthasterias glacialis | 4 | Frequent | 61-80% |
| Nemertesia ramosa | 4 | Occasional | 61-80% |
| Holothuria (Panningothuria) forskali | 3 | Frequent | 41-60% |
| Echinus esculentus | 3 | Occasional | 61-80% |
| Actinothoe sphyrodeta | 2 | Occasional | 61-80% |
| Axinella dissimilis | 2 | Occasional | 61-80% |
| Clavelina lepadiformis | 2 | Occasional | 41-60% |
| Raspailia (Clathriodendron) hispida | 2 | Occasional | 61-80% |
| Raspailia ramosa | 2 | Occasional | 61-80% |
| Stelligera stuposa | 2 | Occasional | 41-60% |
| Stolonica socialis | 2 | Common | 41-60% |
| Alcyonium glomeratum | 2 | Occasional | 41-60% |
| Porifera | 1 | Occasional | 41-60% |
| Crisularia plumosa | 1 | Common | 41-60% |
| Crisiidae | 1 | Occasional | 41-60% |
| Dysidea fragilis | 1 | Occasional | 41-60% |
| Polymastia boletiformis | 1 | Occasional | 41-60% |
| Parazoanthus axinellae | 1 | Occasional | 41-60% |
Similar biotopes or habitat types
CR.MCR.EcCr.CarSp.PenPcom
This biotope occurs under similar wave-exposure conditions as CR.HCR.XFa.ByErSp.Eun but is found in sites subject to only very weak tidal streams. CR.HCR.XFa.ByErSp.Eun has a more diverse array of sponges (including erect sponges) and 'turf-forming' bryozoans.
CR.HCR.XFa.ByErSp.Cyl
This biotope occurs under similar conditions and depths as CR.HCR.XFa.ByErSp.Eun. A diverse group of sponges, hydroids and bryozoans are found in both biotopes, but it is the absence of E. verrucosa and species such as Parazoanthus axinellae and Isozoanthus sulcatus that distinguishes CR.HCR.XFa.ByErSp.Cyl from CR.HCR.XFa.ByErSp.Eun.
CR.HCR.DpSp.PhaAxi
This biotope occurs under similar wave-exposure conditions as CR.HCR.XFa.ByErSp.Eun but is found in sites subject to only very weak tidal streams and much deeper with a mean depth range of 32-37 m. Although E. verrucosa is present in this biotope, it is not as abundant as in CR.HCR.XFa.ByErSp.Eun. It is the presence of significant numbers of axinellid sponges that distinguishes this biotope.
CR.HCR.XFa.CvirCri
This biotope occurs under similar conditions as CR.HCR.XFa.ByErSp.Eun, but may occur at slightly deeper water depths. CR.HCR.XFa.CvirCri lacks E. verrucosa but has a similar bryozoan and hydroid turf to CR.HCR.XFa.ByErSp.Eun. The latter does have a slightly more diverse range of sponges and ascidians than CR.HCR.XFa.CvirCri.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | CR.MCR.XFa.ErSEun |
Photos
