Description of biotope or habitat type
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Novocrania anomala, Dendrodoa grossularia and Rolandia coralloides on variable salinity circalittoral rock
Physical habitat description
| Salinity | Reduced (18-30ppt), Variable (18-35 ppt), Low (<18ppt) |
|---|---|
| Wave exposure | Sheltered, Very sheltered |
| Tidal streams | Weak (>1 kn), Very weak (negligible) |
| Substratum | Bedrock, boulders |
| Zone | Circalittoral - lower |
| Depth Band | 5-10 m, 10-20 m, 20-30 m, 30-50 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 variant typically occurs on lower circalittoral silty, bedrock or boulder cliffs and ridges in very wave-sheltered fjordic sealochs subjected to variable salinity regimes (such as Loch Etive). In these sheltered conditions, there are frequently dense populations of the ascidian Dendrodoa grossularia, the brachiopod Novocrania anomala and to a lesser extent, the brachiopod Terebratulina retusa, which are able to tolerate the variable salinity. Other solitary ascidians that may be present include Ciona intestinalis, Corella parallelogramma, Ascidiella scabra, Ascidia mentula, Ascidia virginea and Polycarpa pomaria. The anemone Protanthea simplex is occasionally seen, although to a lesser extent than in NeoPro, possibly due to the variable salinity. The hydroids Bougainvillia muscus and Lafoea dumosa, the cup-coral Caryophilia smithii and Rolandia coralloides are occasionally present. The tubes formed by the polychaete Sabella pavonina may be observed standing erect from the rock surface. The rest of the rock surface is usually covered by encrusting red algae and the polychaete Spirobranchus triqueter and Protula tubularia. The sea cucumber Psolus phantapus may be found on the underside of boulders. Other species such as the hermit crab Pagurus bernhardus and the spider crab Hyas araneus may be found amongst the rock/boulders. The starfish Asterias rubens, Crossaster papposus, and Henricia spp. and the sea urchin Psammechinus miliaris are also recorded within this variant. The relatively bare, silty rock supports low numbers of a relatively few species. Although barren rock grazed by the sea urchin Echinus esculentus is found in other sea loch biotopes (see FaAlCr.Pom and FaAlCr.Car), E.esculentus is virtually absent within NeoPro.VS.
Situation
Due to the variable or reduced salinity conditions present where this biotope is found, you tend to find reduced salinity kelp biotopes above NeoPro.VS, such as LsacVSPsa and LsacVSPhy. The very sheltered conditions give rise to muddy sediment slopes or plains beneath NeoPro (CMU) where species such as the seapen Funiculina quadrangularis, the anemone Cerianthus lloydii and the Norway lobster Nephrops norvegicus are typically abundant.
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 |
|---|---|---|---|
| Dendrodoa grossularia | 14 | Common | 41-60% |
| Novocrania anomala | 10 | Frequent | 61-80% |
| Ciona intestinalis | 6 | Occasional | 61-80% |
| Corella parallelogramma | 6 | Occasional | 61-80% |
| Ascidia virginea | 5 | Frequent | 41-60% |
| Spirobranchus triqueter | 4 | Frequent | 41-60% |
| Ascidia mentula | 3 | Occasional | 41-60% |
| Ascidiella scabra | 3 | Occasional | 41-60% |
| Buccinum undatum | 3 | Rare | 41-60% |
| Protanthea simplex | 3 | Occasional | 41-60% |
| Sabella pavonina | 3 | Occasional | 41-60% |
| Corallinaceae | 2 | Frequent | 21-40% |
| Bougainvillia muscus | 2 | Occasional | 41-60% |
| Crossaster papposus | 2 | Occasional | 41-60% |
| Lafoea dumosa | 2 | Occasional | 21-40% |
| Pagurus bernhardus | 2 | Occasional | 41-60% |
| Polycarpa pomaria | 2 | Frequent | 41-60% |
| Psolus phantapus | 2 | Occasional | 41-60% |
| Rolandia coralloides | 2 | Occasional | 41-60% |
| Terebratulina retusa | 2 | Occasional | 41-60% |
| Asterias rubens | 1 | Occasional | 41-60% |
| Caryophyllia smithii | 1 | Occasional | 21-40% |
| Henricia oculata | 1 | Rare | 21-40% |
| Hyas araneus | 1 | Rare | 21-40% |
| Protula tubularia | 1 | Occasional | 21-40% |
| Psammechinus miliaris | 1 | Occasional | 21-40% |
Similar biotopes or habitat types
CR.LCR.BrAs.NovPro.FS
This sub-biotope is found under similar physical conditions as CR.LCR.BrAs.NovPro.VS, but is only in the fully marine, sheltered basins of fjordic sealochs. The ascidian D. grossularia is absent in this sub-biotope, but is commonly recorded in CR.LCR.BrAs.NovPro.VS. However, the anemone P. simplex is recorded in higher abundances in CR.LCR.BrAs.NovPro.FS.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 2015 (15.03) | CR.LCR.BrAs.NeoPro.VS |
