Description of biotope or habitat type
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Laminaria digitata, ascidians and bryozoans on tide-swept sublittoral fringe rock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | Very strong (>6 kn), Strong (3-6 kn), Moderately strong (1-3 kn) |
| Substratum | Bedrock; boulders and cobbles |
| Zone | Sublittoral fringe |
| Depth Band | 0-5 m, Lower 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'
- 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
Sheltered bedrock, boulders and cobbles that are subject to moderate to strong tidal water movement characterised by dense Laminaria digitata, coralline crusts and sponges such as Halichondria panicea. Other seaweeds present include the foliose red seaweeds Chondrus crispus, Palmaria palmata, Cryptopleura ramosa and Mastocarpus stellatus as well as the calcareous Corallina officinalis. Green seaweeds present include Ulva lactuca, Ulva intestinalis and Cladophora rupestris. The increased water movement encourages several filter-feeding faunal groups to occur. The sponges Leucosolenia spp., Sycon ciliatum and Hymeniacidon perlevis frequently occur on steep and overhanging rock faces. The bryozoans Electra pilosa, Membranoptera membranipora and Alcyonidium hirsutum encrust the kelp and other foliose seaweeds. In addition, ascidians such as Ascidiella scabra, Dendrodoa grossularia and colonial ascidians Botryllus byssoides and Botryllus leachi often thrive in this environment encrusting both the rock and the seaweeds. The tube-building polychaete Spirobranchus triqueter can be found on the rock and on the kelp holdfasts along with the barnacle Balanus crenatus. More mobile species such as the gastropods Steromphala cineraria and Calliostoma zizyphinum, the crab Carcinus maenas and the starfish Asterias rubens are also common. Areas where increased tidal movement influences this community can be found in the narrows and/or intertidal sills of sealochs.
Situation
This biotope often occurs immediately below the tide-swept Fucus serratus biotope (SLR.Fserr.T) consequently, some F. serratus may occur in this biotope (typically only Occasional). The sublittoral fringe of similarly sheltered shores that are not tide-swept are generally characterised by mixed Saccharina latissima and L. digitata (Lsac.Ldig) or L. saccharina (Lsac). Below LdigT, at these sheltered, tide-swept sites, a canopy of mixed kelp species often occurs (see XKT and XKTX).
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 |
|---|---|---|---|
| Laminaria digitata | 20 | Abundant | 81-100% |
| Corallinaceae | 8 | Common | 61-80% |
| Halichondria panicea | 5 | Frequent | 61-80% |
| Botryllus schlosseri | 3 | Occasional | 61-80% |
| Chondrus crispus | 3 | Occasional | 41-60% |
| Fucus serratus | 3 | Occasional | 41-60% |
| Palmaria palmata | 3 | Occasional | 41-60% |
| Spirobranchus triqueter | 3 | Occasional | 61-80% |
| Ulva lactuca | 3 | Occasional | 61-80% |
| Membranipora membranacea | 2 | Occasional | 41-60% |
| Alcyonidium hirsutum | 2 | Frequent | 41-60% |
| Bryozoa indet crusts | 2 | Frequent | 41-60% |
| Carcinus maenas | 2 | Rare | 61-80% |
| Corallina officinalis | 2 | Occasional | 41-60% |
| Dynamena pumila | 2 | Occasional | 41-60% |
| Steromphala cineraria | 2 | Occasional | 41-60% |
| Spirorbinae | 2 | Frequent | 41-60% |
| Ascidiella scabra | 1 | Frequent | 21-40% |
| Asterias rubens | 1 | Occasional | 41-60% |
| Balanus crenatus | 1 | Occasional | 21-40% |
| Botrylloides leachii | 1 | Rare | 21-40% |
| Calliostoma zizyphinum | 1 | Rare | 41-60% |
| Cladophora rupestris | 1 | Frequent | 21-40% |
| Cryptopleura ramosa | 1 | Occasional | 41-60% |
| Dendrodoa grossularia | 1 | Occasional | 41-60% |
| Ulva | 1 | Occasional | 41-60% |
| Mastocarpus stellatus | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
IR.MIR.KR.Ldig
Occur in non tide-swept areas and lacks the characteristic community of filter-feeders, though the individual species may be present.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1995 | LRK.LDIG.T |
Photos
