Description of biotope or habitat type
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Alcyonium digitatum and Metridium senile on moderately wave-exposed circalittoral steel wrecks
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed |
| Tidal streams | Moderately strong (1-3 kn), Weak (>1 kn) |
| Substratum | Artificial, wrecks |
| Zone | Circalittoral - lower |
| 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 biotope is found on moderately wave-exposed circalittoral steel wrecks that are subject to moderately strong to weak tidal streams. The vertical and upward facing sides of the wreck stand proud of the seabed, and may be colonised by dense aggregations of Alcyonium digitatum, Metridium senile and Actinothoe sphyrodeta. Caryophyllia smithii and Corynactis viridis are also recorded with varying abundance. A mixed faunal turf may also be present on the vertical sides, with Nemertesia antennina, Flustra foliacea and Crisularia plumosa. Where tidal stream strength is elevated, for example if the wreck is situated in a straight or sound, the hydroid Tubularia indivisa may prevail. Crustaceans such as the crabs Necora puber, Maja squinado and Cancer pagurus, the lobster Homarus gammarus and barnacles are all recorded. The top shell Calliostoma zizyphinum is also recorded.
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 |
|---|---|---|---|
| Alcyonium digitatum | 24 | Occasional | 81-100% |
| Metridium senile | 16 | Common | 61-80% |
| Necora puber | 10 | 61-80% | |
| Actinothoe sphyrodeta | 8 | Occasional | 61-80% |
| Maja squinado | 8 | Occasional | 41-60% |
| Cancer pagurus | 7 | Rare | 61-80% |
| Hydrozoa | 4 | Frequent | 21-40% |
| Cirripedia | 3 | Frequent | 21-40% |
| Flustra foliacea | 3 | Occasional | 21-40% |
| Caryophyllia smithii | 2 | Occasional | 21-40% |
| Nemertesia antennina | 2 | Occasional | 21-40% |
| Tubularia indivisa | 2 | Common | 1-20% |
| Homarus gammarus | 2 | Rare | 21-40% |
| Crisularia plumosa | 1 | Frequent | 1-20% |
| Calliostoma zizyphinum | 1 | Occasional | 21-40% |
| Corynactis viridis | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
Not applicable or unknown.
