Description of biotope or habitat type
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Balanus crenatus and Tubularia indivisa on extremely tide-swept circalittoral rock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Extremely exposed, Very exposed, Exposed, Moderately exposed, Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | Very strong (>6 kn), Strong (3-6 kn) |
| Substratum | Bedrock, boulder, cobble |
| Zone | Circalittoral - lower, Circalittoral - upper |
| Depth Band | 0-5 m, 5-10 m, 10-20 m, 20-30 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
This biotope typically occurs on upward-facing, extremely tide-swept, circalittoral bedrock, boulders and cobbles found in a broad spectrum of wave-exposures. It is characterised by a few species that are capable of maintaining a foothold in strong tides. These species either form a flat, adherent crust in the case of the barnacle Balanus crenatus, or have strong attachment points and are flexible, bending with the tide, such as the turf of the hydroid Tubularia indivisa. Other species able to tolerate these very strong tides, or just situated slightly out of the main force of the current, include the sponge Halichondria panicea, the robust hydroid Sertularia argentea and current-tolerant anemones such as Cylista elegans, Urticina felina and Metridium senile. Mobile species such as the starfish Asterias rubens, the crab Cancer pagurus and the whelk Nucella lapillus may also be present.
Situation
This biotope is typically occurs in deep, very tide-swept straights, sounds and narrows with a bedrock/boulder/cobble slope. Kelp forest (LhypT) occurs in shallower water.
Temporal variation
Not known.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Balanus crenatus | 28 | Abundant | 81-100% |
| Tubularia indivisa | 18 | Frequent | 81-100% |
| Cylista elegans | 10 | Frequent | 61-80% |
| Asterias rubens | 7 | Occasional | 61-80% |
| Cancer pagurus | 5 | Occasional | 61-80% |
| Sertularia argentea | 5 | Frequent | 41-60% |
| Urticina felina | 4 | Occasional | 61-80% |
| Alcyonidium diaphanum | 3 | Occasional | 41-60% |
| Metridium senile | 3 | Occasional | 41-60% |
| Bryozoa | 2 | Occasional | 41-60% |
| Flustra foliacea | 2 | Occasional | 41-60% |
| Halichondria panicea | 1 | Common | 21-40% |
| Nucella lapillus | 1 | Common | 21-40% |
Similar biotopes or habitat types
CR.HCR.FaT.CTub.CuSp
This biotope occurs under similar conditions to CR.HCR.FaT.BalTub although it tends to be found more on steep and vertical faces. CR.HCR.FaT.CTub.CuSp contains a more diverse range of sponges, bryozoans and ascidians than CR.HCR.FaT.BalTub. They both contain dense carpets of the robust hydroid T. indivisa.
CR.HCR.FaT.CTub.Adig
This biotope occurs under similar wave-exposed conditions to CR.HCR.FaT.BalTub, but is subject to slightly weaker tides, which is perhaps reflected in the greater abundance of Alcyonium digitatum. Both sub-biotopes have a similarly impoverished epifauna, although CR.HCR.FaT.CTub.Adig has a slightly more diverse range of sponges.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | CR.ECR.BS.BalTub |
