Description of biotope or habitat type
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Sparse Modiolus modiolus, dense Cerianthus lloydii and burrowing holothurians on sheltered circalittoral stones and mixed sediment
Physical habitat description
| Salinity | Full (30-35 ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | Weak (>1 kn), Very weak (negligible) |
| Substratum | Pebbles, boulders and cobbles on mud or muddy gravel |
| Zone | Infralittoral - lower, Circalittoral |
| Depth Band | 10-20 m, 20-30 m, 30-50 m |
| Other Features |
Biotope origin
| Derived using data from | Various |
| Faunal group | 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
Pebbles and cobbles on mud or muddy gravel in sea lochs with frequent Cerianthus lloydii and occasional Modiolus modiolus. Large burrowing holothurians may include Psolus phantapus, Panningia hyndmani, Thyonidium commune, Thyone fusus and Leptopentacta elongate. Many of these species only extend their tentacles above the sediment surface seasonally and are likely to be under recorded by epifaunal surveys. Other more conspicuous characterising taxa include Pagurus bernhardus, Asterias rubens, and Buccinum undatum. This biotope is well developed in the Clyde sea lochs, although many examples are rather species-poor. Some examples in south-west Scottish sea lochs have greater quantities of boulders and cobbles and therefore have a richer associated biota (compared with other sheltered Modiolus bed biotopes such as SS.SBR.SMus.ModHAs). Examples in Shetland are somewhat different in having the cucumber Cucumaria frondosa amongst sparse Modiolus beds and a slightly different balance in abundance of other species; for example the brittlestar Ophiopholis aculeata is more abundant in these far northern examples in the voes and narrows.
Situation
No situation data available.
Temporal variation
No temporal data available.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Pagurus bernhardus | 16 | Frequent | 81-100% |
| Cerianthus lloydii | 15 | Frequent | 81-100% |
| Modiolus modiolus | 9 | Occasional | 61-80% |
| Asterias rubens | 8 | Occasional | 61-80% |
| Buccinum undatum | 5 | Occasional | 61-80% |
| Psammechinus miliaris | 5 | Occasional | 41-60% |
| Spirobranchus triqueter | 4 | Occasional | 41-60% |
| Echinus esculentus | 4 | Occasional | 41-60% |
| Liocarcinus depurator | 3 | Occasional | 41-60% |
| Ophiura albida | 3 | Frequent | 41-60% |
| Aequipecten opercularis | 2 | Occasional | 41-60% |
| Alcyonium digitatum | 2 | Rare | 41-60% |
| Carcinus maenas | 2 | Occasional | 41-60% |
| Hydractinia echinata | 2 | Occasional | 21-40% |
| Seraphsidae | 2 | Occasional | 41-60% |
| Corallinaceae | 1 | Occasional | 21-40% |
| Hyas araneus | 1 | Occasional | 21-40% |
| Munida rugosa | 1 | Occasional | 21-40% |
| Thyone fusus | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
SS.SBR.SMus.ModHAs
SS.SBR.SMus.ModHAs occurs in similar physiographic features, although SS.SMx.CMx.ClloModHo is in softer sediment in some cases, and with a much lower abundance of Modiolus, and a lower diversity in general. There may some overlap in these two biotopes as several of the holothurians extend their tentacles above the surface of the sediment for only a limited amount of time during the year.Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SMx.CMx.ClloModHo | Sparse Modiolus modiolus, dense Cerianthus lloydii and burrowing holothurians on sheltered circalittoral stones and mixed sediment |
| 2004 (04.05) | SS.SMx.CMx.ClloModHo | Sparse Modiolus modiolus, dense Cerianthus lloydii and burrowing holothurians on sheltered circalittoral stones and mixed sediment |
| 1997 (97.06) | SS.CMX.ModHo | Sparse Modiolus modiolus, dense Cerianthus lloydii and burrowing holothurians on sheltered circalittoral stones and mixed sediment |
| 1996 (6.95) | SCR.ModHo |