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.
Modiolus modiolus beds with fine hydroids and large solitary ascidians on very sheltered circalittoral mixed substrata
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Sheltered, Very sheltered |
| Tidal streams | Strong (3-6 kn), Moderately strong (1-3 kn), Weak (>1 kn) |
| Substratum | Pebble, gravel and shells on sandy mud sediments |
| Zone | Circalittoral, Infralittoral |
| Depth Band | 5-10 m, 10-20 m, 20-30 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
Beds or scattered clumps of Modiolus modiolus in generally sheltered conditions with only slight tidal movement. Typically occurs in sea lochs and the Shetland voes. Brittlestars Ophiothrix fragilis and Ophiocomina nigra, as well as Ophiopholis aculeata are often frequent, sometimes forming a dense bed as described in SS.SMx.CMx.OphMx. The queen scallop Aequipecten opercularis is often present in moderate abundances. Large solitary ascidians (Ascidiella aspersa, Corella parallelogramma, Dendrodoa grossularia) and fine hydroids (Kirchenpaueria pinnata) are present attached to the mussel shells. Decapods such as hermit crabs (Pagurus bernhardus) and spider crabs (Hyas araneus) are typically present. Coralline algal crusts may be found on the mussel shells, with some red seaweeds in shallower water such as Phycodrys rubens. 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.
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 | 19 | Common | 81-100% |
| Ophiothrix fragilis | 8 | Frequent | 61-80% |
| Echinus esculentus | 8 | Occasional | 81-100% |
| Aequipecten opercularis | 6 | Frequent | 61-80% |
| Pagurus bernhardus | 6 | Occasional | 61-80% |
| Asterias rubens | 5 | Occasional | 61-80% |
| Spirobranchus triqueter | 4 | Frequent | 21-40% |
| Buccinum undatum | 3 | Occasional | 61-80% |
| Dendrodoa grossularia | 3 | Occasional | 41-60% |
| Hyas araneus | 3 | Occasional | 61-80% |
| Corallinaceae | 2 | Frequent | 41-60% |
| Balanus balanus | 2 | Occasional | 41-60% |
| Balanus crenatus | 2 | Occasional | 41-60% |
| Corella parallelogramma | 2 | Occasional | 41-60% |
| Crossaster papposus | 2 | Rare | 41-60% |
| Liocarcinus depurator | 2 | Occasional | 41-60% |
| Ophiocomina nigra | 2 | Frequent | 21-40% |
| Antedon bifida | 1 | Occasional | 21-40% |
| Ascidiella aspersa | 1 | Frequent | 21-40% |
| Steromphala cineraria | 1 | Occasional | 21-40% |
| Kirchenpaueria pinnata | 1 | Occasional | 41-60% |
| Ophiopholis aculeata | 1 | Occasional | 21-40% |
| Phycodrys rubens | 1 | Occasional | 41-60% |
| Seraphsidae | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
SS.SMx.CMx.ClloModHo
SS.SMx.CMx.ClloModHo occurs in similar physiographic features, although seems to be in softer sediment in some cases and with a much lower abundance of Modiolus and a lower diversity in general.
SS.SBR.SMus.ModMvar
SS.SBR.SMus.ModMvar is a more species rich biotope with far more sponges and hydroids growing on and amongst the Modiolus and large numbers of Mimachlamys varia.Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SBR.SMus.ModHAs | Modiolus modiolus beds with fine hydroids and large solitary ascidians on very sheltered circalittoral mixed substrata |
| 2004 (04.05) | SS.SBR.SMus.ModHAs | Modiolus modiolus beds with fine hydroids and large solitary ascidians on very sheltered circalittoral mixed substrata |
| 1997 (97.06) | SS.CR.SCR.Mod.ModHas | Modiolus modiolus beds with fine hydroids and large solitary ascidians on very sheltered circalittoral mixed substrata |