Description of biotope or habitat type
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Ephemeral green or red seaweed communities (freshwater or sand-influenced)
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Exposed, Moderately exposed, Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | |
| Substratum | Bedrock; boulders |
| Zone | Littoral fringe - lower, Eulittoral |
| Depth Band | Lower shore, Mid shore, Upper shore |
| 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'
Point data based on records in the UK Marine Recorder Snapshot.
Description
Ephemeral seaweeds on disturbed littoral rock in the lower to upper shore. Dominant green seaweeds include Ulva intestinalis, Ulva lactuca and the red seaweeds Rhodothamniella floridula and Porphyra purpurea. Winkles such as Littorina littorea and Littorina saxatilis, the limpet Patella vulgata and the barnacles Semibalanus balanoides can occur, though usually in low abundance. The crab Carcinus maenas can be found where boulders are present, while the barnacle Austrominius modestus is usually present on sites subject to variable salinity. On moderately exposed shores, the biotope is Ulva spp. on freshwater-influenced or unstable upper shore rock (Ent) or P. purpurea and/or Ulva spp. on sand-scoured mid to lower eulittoral rock (EntPor). Eulittoral mixed substrata subject to variations in salinity and/or siltation characterised by dense blankets of ephemeral green and red seaweeds (EphX), or if the substratum is too mobile or disturbed to support a seaweed community (BLitX). These are biotopes with a low species diversity and the relatively high number of species in the characterising species list are due to a variation in the species composition from site to site, not to high species richness on individual sites.
Situation
This biotope complex occurs the splash zone, sometimes on cliff faces, and throughout the main intertidal zone.
Temporal variation
No temporal variation data available.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Ulva intestinalis | 37 | Common | 61-80% |
| Austrominius modestus | 10 | Occasional | 21-40% |
| Littorina littorea | 7 | Occasional | 21-40% |
| Chlorophyceae | 5 | Abundant | 21-40% |
| Littorina saxatilis | 5 | Occasional | 21-40% |
| Carcinus maenas | 4 | Occasional | 21-40% |
| Patella vulgata | 4 | Occasional | 21-40% |
| Semibalanus balanoides | 3 | Occasional | 41-60% |
| Ulva lactuca | 3 | Occasional | 21-40% |
| Fucus vesiculosus | 2 | Occasional | 21-40% |
| Rhodothamniella floridula | 1 | 1-20% | |
| Porphyra purpurea | 1 | 1-20% |
Similar biotopes or habitat types
Not applicable or unknown.
Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | LR.LR (part) |