Description of biotope or habitat type
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Mixed kelps with scour-tolerant and opportunistic foliose red seaweeds on scoured or sand-covered infralittoral rock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Exposed, Moderately exposed |
| Tidal streams | Moderately strong (1-3 kn), Weak (>1 kn) |
| Substratum | Bedrock; boulders |
| Zone | Infralittoral |
| Depth Band | 0-5 m, 5-10 m, 10-20 m |
| Other Features | Close proximity to sand |
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
Bedrock and boulders, often in tide-swept areas, that are subject to scouring or periodic burial by sand, characterised by a canopy of mixed kelps such as Saccharina latissima, Laminaria hyperborea and Saccorhiza polyschides and the brown seaweed Desmarestia aculeata; there may also be an understorey of foliose seaweeds that can withstand scour such as Plocamium cartilagineum, Chondrus crispus, Dilsea carnosa, Metacallophyllis laciniata as well as the filamentous Heterosiphonia plumosa and the foliose brown seaweed Dictyota dichotoma. The perennial red seaweed Vertebrata byssoides re-grows in the summer months. The L. hyperborea stipes often support a growth of epiphytes, such as Delesseria sanguinea, Phycodrys rubens and Cryptopleura ramosa. The scour can reduce the rock surface to bare coralline crusts at times; sponge crusts and the colonial ascidian Botryllus schlosseri can also grow on the stipes and holdfasts. The faunal diversity on the rock is usually low and restricted to robust, low-profile animals such as the tube-building polychaete Spirobranchus triqueter, the barnacle Balanus crenatus, encrusting bryozoans such as Membranipora membranacea, the anthozoan Urticina felina, the starfish Asterias rubens and the urchin Echinus esculentus. Deeper sites support more hydroids and bryozoans, particularly Bugula spp. Where this biotope occurs in very shallow water Laminaria digitata may be found in combination with the other kelp species. Other species present only in shallow water include the red algae Corallina officinalis and the sand-binding alga Rhodothamniella floridula.
Situation
This biotope often occurs below a L. hyperborea forest (LhypR.Ft, Lhyp.Ft or LhypT.Ft), close to a rock-sediment boundary. It is also found on low-lying rock outcrops surrounded by sand or mixed sediment and nearby biotopes on mixed substrata may include EphR, ProtAhn or in very shallow water LsacChoR. A Flustra foliacea community (FluCoAs) often dominates deeper sand-scoured circalittoral rock.
Temporal variation
During late autumn and winter seaweeds are sparse, leaving predominantly kelp and encrusting coralline algae. This is due in part to periods of intense scouring during stormy months, which may strip off all but the most tenacious seaweeds. In addition there will be the natural die back of many of the seaweeds such as B. byssoides and C. ciliata during the winter months which become conspicuous again during the summer months.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Laminaria hyperborea | 10 | Common | 61-80% |
| Saccharina latissima | 9 | Frequent | 61-80% |
| Plocamium cartilagineum | 6 | Frequent | 61-80% |
| Corallinaceae | 5 | Frequent | 41-60% |
| Cryptopleura ramosa | 4 | Frequent | 41-60% |
| Asterias rubens | 3 | Occasional | 41-60% |
| Delesseria sanguinea | 3 | Occasional | 41-60% |
| Dictyota dichotoma | 3 | Frequent | 41-60% |
| Dilsea carnosa | 3 | Occasional | 41-60% |
| Steromphala cineraria | 3 | Frequent | 41-60% |
| Membranipora membranacea | 2 | Frequent | 21-40% |
| Balanus crenatus | 2 | Frequent | 21-40% |
| Vertebrata byssoides | 2 | Occasional | 41-60% |
| Metacallophyllis laciniata | 2 | Occasional | 41-60% |
| Heterosiphonia plumosa | 2 | Frequent | 41-60% |
| Phycodrys rubens | 2 | Frequent | 41-60% |
| Spirobranchus triqueter | 2 | Frequent | 41-60% |
| Saccorhiza polyschides | 2 | Frequent | 41-60% |
| Botryllus schlosseri | 1 | Occasional | 21-40% |
| Chondrus crispus | 1 | Occasional | 41-60% |
| Corallina officinalis | 1 | Occasional | 21-40% |
| Desmarestia aculeata | 1 | Occasional | 21-40% |
| Urticina felina | 1 | Occasional | 41-60% |
| Echinus esculentus | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
IR.HIR.KSed.XKHal
A tide-swept biotope dominated by Halidrys siliquosa (typically greater than Common) with mixed kelp species that is subject to greater scour than IR.HIR.KSed.XKScrR.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1996 (6.95) | MIR.LsacScrR |
| 1996 (6.95) | MIR.XK |
