Description of biotope or habitat type
To understand more about what this page is describing, see How to use the classification. See also How to cite.
Sparse sponges, Nemertesia spp. and Alcyonidium diaphanum on circalittoral mixed substrata
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed |
| Tidal streams | Moderately strong (1-3 kn) |
| Substratum | Boulders; cobbles; pebbles |
| Zone | Circalittoral |
| 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 sand-scoured, circalittoral boulders, cobbles and pebbles that are subject to moderately strong tidal streams (referred to as lag-cobbles locally). It is characterised by sparse sponges and a diverse bryozoan and hydroid turf. The sparse sponge community is primarily composed of Dysidea fragilis and Sycon ciliatum. The mixed faunal turf is composed of Nemertesia antennina, Nemertesia ramosa, Halecium halecinum, Sertularia argentea, Alcyonium digitatum, Bugulina flabellata, Bugulina turbinata, Crisularia plumosa, Flustra foliacea, Cellepora pumicosa, Alcyonidium diaphanum, Cellaria fistulosa and crisiid bryozoans. The anemones Epizoanthus couchii, Cylista elegans and Cerianthus lloydii may also be recorded. Echinoderms such as the starfish Asterias rubens, Crossaster papposus, Henricia oculata and the crinoid Antedon bifida. Other species present include the colonial ascidian Clavelina lepadiformis, the barnacle Balanus crenatus, the top shell Steromphala cineraria, the polychaete Spirobranchus triqueter, the ascidian Morchellium argus, Prosthecareus vittatus and the crab Cancer pagurus. It is distributed off Pen Llyn and over considerable areas of the Irish Sea.
Situation
No situation data available.
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 |
|---|---|---|---|
| Nemertesia antennina | 10 | Occasional | 81-100% |
| Alcyonium digitatum | 6 | Occasional | 81-100% |
| Clavelina lepadiformis | 5 | Occasional | 61-80% |
| Epizoanthus couchii | 5 | Occasional | 61-80% |
| Bugulina flabellata | 4 | Occasional | 61-80% |
| Asterias rubens | 3 | Occasional | 61-80% |
| Flustra foliacea | 3 | Occasional | 61-80% |
| Nemertesia ramosa | 3 | Occasional | 61-80% |
| Alcyonidium diaphanum | 2 | Occasional | 61-80% |
| Antedon bifida | 2 | Occasional | 41-60% |
| Balanus crenatus | 2 | Common | 41-60% |
| Bugulina turbinata | 2 | Occasional | 41-60% |
| Cerianthus lloydii | 2 | Occasional | 41-60% |
| Crossaster papposus | 2 | Occasional | 41-60% |
| Dysidea fragilis | 2 | Occasional | 41-60% |
| Cylista elegans | 2 | Frequent | 41-60% |
| Crisularia plumosa | 1 | Occasional | 21-40% |
| Cancer pagurus | 1 | Occasional | 21-40% |
| Cellaria fistulosa | 1 | Common | 21-40% |
| Cellepora pumicosa | 1 | Occasional | 21-40% |
| Crisiidae | 1 | Frequent | 21-40% |
| Steromphala cineraria | 1 | Occasional | 41-60% |
| Halecium halecinum | 1 | Occasional | 41-60% |
| Henricia oculata | 1 | Occasional | 41-60% |
| Morchellium argus | 1 | Frequent | 21-40% |
| Spirobranchus triqueter | 1 | Occasional | 41-60% |
| Prostheceraeus vittatus | 1 | Rare | 41-60% |
| Sycon ciliatum | 1 | Occasional | 21-40% |
| Sertularia argentea | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
CR.HCR.XFa.FluCoAs.X
This biotope occurs under more wave-exposed conditions subject to slightly weaker tidal streams. Flustra foliacea is present in higher abundances in CR.HCR.XFa.FluCoAs.X.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | CR.MCR.ByH.SNemAdia |