Description of biotope or habitat type
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Lithothamnion glaciale maerl beds in tide-swept variable salinity infralittoral gravel
Physical habitat description
| Salinity | Full (30-35 ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | Strong (3-6 kn), Moderately strong (1-3 kn), Weak (>1 kn) |
| Substratum | Maerl; shell gravel; stones and coarse sediment |
| Zone | Infralittoral |
| Depth Band | 0-5 m, 5-10 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
Upper infralittoral tide-swept channels of coarse sediment in full or variable salinity conditions support distinctive beds of Lithothamnion glaciale maerl 'rhodoliths'. Phymatolithon calcareum may also be present as a more minor maerl component. Associated fauna and flora may include species found in other types of maerl beds (and elsewhere), e.g. Spirobranchus triqueter, Cerianthus lloydii, Sabella pavonina, Chaetopterus variopedatus, Lanice conchilega, Mya truncata, Plocamium cartilagineum and Phycodrys rubens. SS.SMp.Mrl.Lgla, however, also has a fauna that reflects the slightly reduced salinity conditions, e.g. Psammechinus miliaris is often present in high numbers along with other grazers such as chitons and Tectura spp. Hyas araneus, Ophiothrix fragilis, Ophiocomina nigra and the brown seaweed Dictyota dichotoma are also typically present at sites. In Scottish lagoons this biotope may show considerable variation but the community falls within the broad description defined here.
Situation
This biotope can often be found at the upper end of Scottish sea lochs where the variable salinity of the habitat may not be immediately obvious.
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 |
|---|---|---|---|
| Lithothamnion glaciale | 16 | Abundant | 61-80% |
| Ophiocomina nigra | 12 | Abundant | 61-80% |
| Ophiothrix fragilis | 12 | Frequent | 61-80% |
| Asterias rubens | 11 | Occasional | 81-100% |
| Dictyota dichotoma | 6 | Frequent | 41-60% |
| Carcinus maenas | 3 | Occasional | 41-60% |
| Corallina officinalis | 3 | Occasional | 41-60% |
| Psammechinus miliaris | 3 | Frequent | 21-40% |
| Chondrus crispus | 2 | Occasional | 41-60% |
| Pagurus bernhardus | 2 | Frequent | 21-40% |
| Spirobranchus triqueter | 2 | Frequent | 21-40% |
| Phymatolithon calcareum | 2 | Abundant | 1-20% |
| Buccinum undatum | 1 | Occasional | 21-40% |
| Cerianthus lloydii | 1 | Frequent | 21-40% |
| Chorda filum | 1 | Frequent | 21-40% |
| Steromphala cineraria | 1 | Occasional | 21-40% |
| Saccharina latissima | 1 | Occasional | 21-40% |
| Bonnemaisonia hamifera | 1 | Frequent | 21-40% |
| Ostrea edulis | 1 | Frequent | 1-20% |
| Echinus esculentus | 1 | Occasional | 41-60% |
Similar biotopes or habitat types
Not applicable or unknown.
Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | IGS.Lgla |