Description of biotope or habitat type
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Modiolus modiolus beds with hydroids and red seaweeds on tide-swept circalittoral mixed substrata
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed, Sheltered, Very sheltered |
| Tidal streams | Strong (3-6 kn), Moderately strong (1-3 kn) |
| Substratum | Cobbles, pebbles and Modiolus shells |
| Zone | Infralittoral - lower, 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 |
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
Modiolus beds on mixed substrata (cobbles, pebbles and coarse muddy sediments) in moderately strong currents or wave exposed areas, typically on the open coast but also in tide-swept channels of marine inlets. Ophiothrix fragilis are often common in this biotope along with the calcareous tubes of Spirobranchus triqueter, anemones such as Alcyonium digitatum and Urticina felina and hydroids such as Abietinaria abietina and Sertularia argentea. Buccinum undatum may also be important and in some areas the clam Mimachlamys varia may be frequent but not in the same abundances as in SS.SBR.SMus.ModMvar. Little information on the infaunal component is given here although it is likely that it is very rich and may highlight more subtle differences in the Modiolus biotopes. This biotope is typified by examples off the north-west Lleyn Peninsula in north Wales and off Co. Down, Northern Ireland.
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 |
|---|---|---|---|
| Modiolus modiolus | 27 | Abundant | 81-100% |
| Ophiothrix fragilis | 13 | Common | 61-80% |
| Alcyonium digitatum | 10 | Common | 61-80% |
| Asterias rubens | 8 | Occasional | 81-100% |
| Buccinum undatum | 4 | Occasional | 61-80% |
| Spirobranchus triqueter | 4 | Frequent | 41-60% |
| Abietinaria abietina | 3 | Frequent | 41-60% |
| Pagurus bernhardus | 3 | Occasional | 61-80% |
| Ophiocomina nigra | 2 | Frequent | 41-60% |
| Phycodrys rubens | 2 | Common | 21-40% |
| Psammechinus miliaris | 2 | Common | 21-40% |
| Urticina felina | 2 | Occasional | 41-60% |
| Echinus esculentus | 2 | Occasional | 41-60% |
| Balanus crenatus | 1 | Frequent | 21-40% |
| Ciona intestinalis | 1 | Rare | 21-40% |
| Crossaster papposus | 1 | Rare | 21-40% |
| Sertularia argentea | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
SS.SBR.SMus.ModMx
Tends to occur in deeper water than SS.SBR.SMus.ModT and has a more divesre infauna as a result of the lower tidal current strength.Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SBR.SMus.ModT | Modiolus modiolus beds with hydroids and red seaweeds on tide-swept circalittoral mixed substrata |
| 2004 (04.05) | SS.SBR.SMus.ModT | Modiolus modiolus beds with hydroids and red seaweeds on tide-swept circalittoral mixed substrata |
| 1997 (97.06) | SS.MCR.M.ModT | Modiolus modiolus beds with hydroids and red seaweeds on tide-swept circalittoral mixed substrata |