Description of biotope or habitat type
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Hartlaubella gelatinosa and Conopeum reticulum on low salinity infralittoral mixed substrata
Physical habitat description
| Salinity | Reduced (18-30ppt), Low (<18ppt) |
|---|---|
| Wave exposure | Very sheltered, Extremely sheltered |
| Tidal streams | Moderately strong (1-3 kn) |
| Substratum | Boulders, cobbles and mixed sediments |
| Zone | Infralittoral |
| Depth Band | 0-5 m |
| Other Features |
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 estuarine mixed hard substrata colonised by very sparse communities of animals with low species richness and with a few seaweeds in very shallow water. In the Tamar estuary the hydroid Hartlaubella gelatinosa and bryozoan Conopeum reticulum are found on stones. In the River Dart the bryozoan Amathia imbricata is most abundant. The mussel Mytilus edulis, the crab Carcinus maenas and the hydroid Obelia dichotoma can be present. A similar brackish-water rocky biotope is recorded from the Bann Estuary, Northern Ireland. There are considerable differences in species composition between sites, but all occur in brackish turbid-water conditions. More information required to validate this description.
Situation
Insufficient information to describe neighbouring biotopes.
Temporal variation
Unknown.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Hartlaubella gelatinosa | 33 | Frequent | 81-100% |
| Obelia dichotoma | 22 | Rare | 81-100% |
| Conopeum reticulum | 11 | 81-100% | |
| Amathia imbricata | 11 | 81-100% | |
| Carcinus maenas | 11 | Occasional | 81-100% |
| Mytilus edulis | 11 | Rare | 81-100% |
Similar biotopes or habitat types
Not applicable or unknown.
Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1996 (6.95) | SCR.HarCon (part) |