Description of biotope or habitat type
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Porphyra purpurea and Ulva spp. on sand-scoured mid or lower eulittoral rock
Physical habitat description
| Salinity | Full (30-35 ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Exposed, Moderately exposed |
| Tidal streams | |
| Substratum | Bedrock; boulders |
| Zone | Eulittoral |
| Depth Band | Mid shore |
| Other Features | Sand-scour |
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
Exposed and moderately exposed mid-shore bedrock and boulders occurring adjacent to areas of sand which significantly affects the rock. As a consequence of sand-abrasion, wracks such as Fucus vesiculosus or Fucus spiralis are scarce and the community is typically dominated by ephemeral red or green seaweeds, particularly the foliose red seaweed Porphyra purpurea and green seaweeds such as Ulva spp. Under the blanket of ephemeral seaweeds, the barnacles Semibalanus balanoides or Austrominius modestus and the limpet Patella vulgata may occur in the less scoured areas, along with the occasional winkles Littorina littorea and Littorina saxatilis. Few other species are present.
Situation
Usually found below the species impoverished biotope dominated by Ulva spp. (Ent) and above the F. spiralis zone (Fspi). It may replace the zone dominated by the wrack Pelvetia canaliculata (PelB). In areas where sand abrasion is less severe, the sand-binding red alga Rhodothamniella floridula occurs with other sand-tolerant seaweeds and the wrack Fucus serratus (Rho), along with the mussel Mytilus edulis.
Temporal variation
Seasonal fluctuations in the abundance of the Enteromorpha spp. and the P. purpurea will occur, especially as a result of storm action.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Ulva | 48 | Abundant | 41-60% |
| Porphyra purpurea | 11 | Frequent | 41-60% |
| Littorina littorea | 7 | Occasional | 41-60% |
| Semibalanus balanoides | 6 | Occasional | 41-60% |
| Ulva intestinalis | 3 | 21-40% | |
| Littorina saxatilis | 3 | Occasional | 21-40% |
| Patella vulgata | 3 | Occasional | 21-40% |
| Fucus vesiculosus | 3 | Occasional | 21-40% |
| Austrominius modestus | 2 | Occasional | 21-40% |
| Ulva prolifera | 2 | 21-40% | |
| Mytilus edulis | 2 | Frequent | 21-40% |
| Ulva lactuca | 2 | Frequent | 21-40% |
| Porphyra | 2 | Frequent | 21-40% |
Similar biotopes or habitat types
LR.FLR.Eph.Ulv
Occurs from the mid eulittoral to the supralittoral zone, often in freshwater influenced habitats. It has a lower species richness and the red seaweed P. purpurea and the wracks F. spiralis or F. vesiculosus are usually not present. The winkle L. littorea is also absent.
LR.FLR.Eph.EphX
Occurs in more estuarine conditions and on mixed substrata. A very similar biotope.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 2015 (15.03) | LR.FLR.Eph.EntPor |
| 1996 (6.95) | MLR.Eph.Por |
| 1995 | LRK.EPH |
Photos
