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Marine Habitat Classification

Description of biotope or habitat type

To understand more about what this page is describing, see How to use the classification. See also How to cite.

   Neocrania anomala, Dendrodoa grossularia and Sarcodictyon roseum 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.

Distribution of habitat CR.LCR.BrAs.NeoPro.VS <I>Neocrania anomala</I>, <I>Dendrodoa grossularia</I> and <I>Sarcodictyon roseum</I> on variable salinity circalittoral rock

  • 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.


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 Neocrania 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 ramosa and Lafoea dumosa, the cup-coral Caryophilia smithii and Sarcodictyon roseum 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 Pomatoceros 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.


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
Bougainvillia ramosa 2 Occasional 41-60 %
Lafoea dumosa 2 Occasional 21-40 %
Sarcodictyon roseum 2 Occasional 41-60 %
Protanthea simplex 3 Occasional 41-60 %
Caryophyllia smithii 1 Occasional 21-40 %
Sabella pavonina 3 Occasional 41-60 %
Pomatoceros triqueter 4 Frequent 41-60 %
Protula tubularia 1 Occasional 21-40 %
Pagurus bernhardus 2 Occasional 41-60 %
Hyas araneus 1 Rare 21-40 %
Buccinum undatum 3 Rare 41-60 %
Neocrania anomala 10 Frequent 61-80 %
Terebratulina retusa 2 Occasional 41-60 %
Crossaster papposus 2 Occasional 41-60 %
Henricia oculata 1 Rare 21-40 %
Asterias rubens 1 Occasional 41-60 %
Psammechinus miliaris 1 Occasional 21-40 %
Psolus phantapus 2 Occasional 41-60 %
Ciona intestinalis 6 Occasional 61-80 %
Corella parallelogramma 6 Occasional 61-80 %
Ascidiella scabra 3 Occasional 41-60 %
Ascidia mentula 3 Occasional 41-60 %
Ascidia virginea 5 Frequent 41-60 %
Polycarpa pomaria 2 Frequent 41-60 %
Dendrodoa grossularia 14 Common 41-60 %
Corallinaceae 2 Frequent 21-40 %

Similar biotopes or habitat types

This sub-biotope is found under similar physical conditions as NeoPro.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 NeoPro.VS. However, the anemone P. simplex is recorded in higher abundances in NeoPro.FS.


CR.LCR.BRAS.NeoPro.VS Neocrania anomala, Dendrodoa grossularia and Sarcodictyon roseum on variable salinity circalittoral rock, Eilean Rairidh, Loch a'Chairn Bhain. Bernard Picton © JNCC
CR.LCR.BRAS.NeoPro.VS Neocrania anomala, Dendrodoa grossularia and Sarcodictyon roseum on variable salinity circalittoral rock, Eilean Rairidh, Loch a'Chairn Bhain. Bernard Picton © JNCC

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