Description of biotope or habitat type
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Circalittoral mixed sediment
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed, Sheltered, Very sheltered |
| Tidal streams | Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible) |
| Substratum | Mixed sediment (with stones and shells) |
| Zone | Circalittoral |
| Depth Band | 5-10 m, 10-20 m, 20-30 m, 30-50 m |
| Other Features |
Biotope origin
| Derived using data from | Various |
| Faunal group | Epifauna/infauna |
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
Mixed (heterogeneous) sediment habitats in the circalittoral zone (generally below 15-20 m) including well mixed muddy gravelly sands or very poorly sorted mosaics of shell, cobbles and pebbles embedded in or lying upon mud, sand or gravel. Due to the variable nature of the seabed a variety of communities can develop which are often very diverse. A wide range of infaunal polychaetes, bivalves, echinoderms and burrowing anemones such as Cerianthus lloydii are often present in such habitats and the presence of hard substrata (shells and stones) on the surface enables epifaunal species to become established, particularly hydroids such as Nemertesia spp. and Hydrallmania falcata. The combination of epifauna and infauna can lead to species rich communities. Coarser mixed sediment communities may show a strong resemblance, in terms of infauna, to biotopes within the SS.SCS complex. However, infaunal data for this biotope complex is limited to that described under the biotope SS.SMx.CMx.KurThyMx, and so are not representative of the infaunal component of this biotope complex.
Situation
No situation data available.
Temporal variation
No temporal data available.
Characterising species
| Taxon | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|
| Prionospio fallax | Abundant | 61-80% |
| Asterias rubens | Occasional | 61-80% |
| Thyasira flexuosa | Common | 81-100% |
| Cerianthus lloydii | Frequent | 41-60% |
| Kurtiella bidentata | Frequent | 81-100% |
| Pagurus bernhardus | Occasional | 41-60% |
| Chaetozone setosa | Common | 81-100% |
| Corallinaceae | Occasional | 21-40% |
| Hilbigneris gracilis | Common | 81-100% |
| Alcyonium digitatum | Occasional | 21-40% |
| Nematoda | Frequent | 61-80% |
| Buccinum undatum | Occasional | 21-40% |
| Scoloplos armiger | Abundant | 81-100% |
| Crossaster papposus | Rare | 21-40% |
| Abra alba | Common | 41-60% |
| Lanice conchilega | Occasional | 21-40% |
| Ampelisca tenuicornis | Frequent | 61-80% |
| Liocarcinus depurator | Occasional | 21-40% |
| Chamelea gallina | Common | 61-80% |
| Nemertesia antennina | Occasional | 21-40% |
| Goniada maculata | Common | 61-80% |
| Nemertesia ramosa | Occasional | 21-40% |
| Mediomastus fragilis | Common | 41-60% |
| Ophiocomina nigra | Frequent | 21-40% |
| Nemertea | Common | 61-80% |
| Ophiothrix fragilis | Common | 21-40% |
| Nephtys hombergii | Common | 61-80% |
| Ophiura albida | Frequent | 21-40% |
| Owenia fusiformis | Common | 61-80% |
| Pecten maximus | Occasional | 21-40% |
| Pholoe inornata | Frequent | 61-80% |
| Spirobranchus triqueter | Occasional | 21-40% |
| Phoronis | Common | 41-60% |
| Psolus phantapus | Occasional | 21-40% |
| Scalibregma inflatum | Common | 61-80% |
| Seraphsidae | Occasional | 21-40% |
| Spiophanes bombyx | Frequent | 61-80% |
| Thyone fusus | Occasional | 21-40% |
| Terebellides stroemii | Abundant | 61-80% |
| Urticina felina | Occasional | 21-40% |
| Amphiura filiformis | Abundant | 41-60% |
| Modiolus modiolus | Occasional | 21-40% |
| Eudorella truncatula | Abundant | 41-60% |
| Echinus esculentus | Occasional | 21-40% |
| Galathowenia oculata | Frequent | 41-60% |
| Flustra foliacea | Occasional | 1-20% |
| Glycera alba | Abundant | 41-60% |
| Hydrallmania falcata | Occasional | 1-20% |
| Levinsenia gracilis | Common | 41-60% |
| Nephtys | Common | 41-60% |
| Phaxas pellucidus | Common | 41-60% |
Similar biotopes or habitat types
Not applicable or unknown.
Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SMx.CMx | Circalittoral mixed sediment |
| 2004 (04.05) | SS.SMx.CMx | Circalittoral mixed sediment |
| 1997 (97.06) | SS.CMX | Circalittoral mixed sediments |