Description of biotope or habitat type
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Dense Desmarestia spp. with filamentous red seaweeds on exposed infralittoral cobbles, pebbles and bedrock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Exposed |
| Tidal streams | Moderately strong (1-3 kn), Weak (>1 kn) |
| Substratum | Bedrock & boulders |
| Zone | Infralittoral - upper, Sublittoral fringe |
| Depth Band | 5-10 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
Wave-exposed seasonally mobile substrata (pebbles, cobbles) dominated by dense stands of the brown seaweed Desmarestia aculeata and/or Desmarestia ligulata. Infralittoral pebbles and cobbles that are scoured through mobility during storms, but become stable in the summer allowing the growth of such algae as Desmarestia spp. Filamentous red seaweeds such as Bonnemaisonia asparagoides and Vertebrata byssoides are usually present. Stunted individuals of the kelp such as Laminaria hyperborea and Saccharina latissima may be present where bedrock is available. A variety of foliose red seaweeds such as Cryptopleura ramosa, Chondrus crispus, Plocamium cartilagineum, Hypoglossum hypoglossoides and Nitophyllum punctatum may on occasion be present underneath the kelp canopy. Other red algae including Corallina officinalis, Rhodomela confervoides and coralline crusts including Lithothamnion spp. may be present as well as well as the foliose brown seaweed Dictyota dichotoma and the green Ulva intestinalis. Due to the nature of this biotope the faunal component is very impoverished though the gastropod Steromphala cineraria can be found among the cobbles.
Situation
Often a narrow zone on mixed substrata below a stable zone of kelp on bedrock. Where seasonally mobile substrata affect nearby bedrock this biotope may occur in place of kelp forest.
Temporal variation
See biotope description
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Desmarestia aculeata | 24 | Common | 81-100% |
| Bonnemaisonia asparagoides | 9 | Occasional | 21-40% |
| Vertebrata byssoides | 9 | Frequent | 61-80% |
| Dictyota dichotoma | 6 | Frequent | 41-60% |
| Saccharina latissima | 4 | Occasional | 41-60% |
| Plocamium cartilagineum | 4 | Frequent | 41-60% |
| Cryptopleura ramosa | 3 | Occasional | 21-40% |
| Desmarestia ligulata | 3 | Frequent | 21-40% |
| Hypoglossum hypoglossoides | 3 | Rare | 41-60% |
| Lithothamnion | 3 | Common | 21-40% |
| Spirobranchus triqueter | 3 | Occasional | 21-40% |
| Urticina felina | 3 | Occasional | 21-40% |
| Laminaria | 3 | Frequent | 21-40% |
| Corallinaceae | 2 | Frequent | 21-40% |
| Corallina officinalis | 2 | Occasional | 21-40% |
| Steromphala cineraria | 2 | Frequent | 41-60% |
| Rhodophyta | 2 | Frequent | 21-40% |
| Chondrus crispus | 1 | Frequent | 41-60% |
| Delesseria sanguinea | 1 | Rare | 21-40% |
| Ulva | 1 | Occasional | 21-40% |
| Laminaria hyperborea | 1 | Occasional | 21-40% |
| Nitophyllum punctatum | 1 | Occasional | 21-40% |
| Rhodomela confervoides | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
IR.HIR.KSed.Sac
Occurs on bedrock at slightly more exposed coasts. The kelp Saccorhiza polyschides has a higher abundance (Abundant), while the brown seaweed D. aculeata has a lower abundance (Occasional) than in IR.HIR.KSed.DesFilR.
IR.HIR.KSed.SlatSac
Occurs at similar conditions but at slightly more exposed coasts. The two kelps Saccharina latissima and S. polyschides has a higher abundance (both Common), while the brown seaweed D. aculeata has a lower abundance (Occasional) than in IR.HIR.KSed.DesFilR.