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Marine Habitat Classification


Description of biotope or habitat type

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   Neocrania anomala and Protanthea simplex on very wave-sheltered circalittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Bedrock, boulders
Zone Circalittoral
Depth Band 5-10 m, 10-20 m, 20-30 m, 30-50 m
Other Features Steep, often near vertical slopes

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.FS <I>Neocrania anomala</I> and <I>Protanthea simplex</I> on very wave-sheltered 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.

Description

This variant typically occurs on deep, lower circalittoral bedrock or boulder slopes (often-vertical walls) in the landward, very sheltered basins of fjordic sealochs. In these very sheltered conditions, there are frequently dense populations of the anemone Protanthea simplex growing on the silty boulder or rock slope, and on the tubes of the parchment worm Chaetopterus variopedatus. The underlying rock surfaces are usually covered with encrusting red algae, the polychaete Pomatoceros triqueter, the brachiopod Neocrania anomala, the saddle oyster Pododesmus patelliformis and the conspicuous fan worm Sabella pavonina. Scattered colonies of Alcyonium digitatum are occasionally present along with the hydroid Bougainvillia ramosa. The barnacle Balanus balanus and the hermit crab Pagurus bernhardus is occasionally seen on boulder or rock surface, whilst underneath in crevices, the squat lobster Munida rugosa may be present. A diverse range of solitary ascidians, typically found in sheltered conditions, are often present including Ciona intestinalis, Corella parallelogramma, Polycarpa pomaria, Ascidia mentula and Ascidia virginea. Echinoderms such as brittlestars Ophiothrix fragilis are frequently seen with their arms protruding from crevices in the rock, whilst the starfish Asterias rubens, the sea urchin Echinus esculentus and Psammechinus miliaris are occasionally found on the boulder or rock surface. The whelk Buccinum undatum is often present but in very low numbers.

Situation

Where this biotope occurs on vertical rock cliffs, you tend to find silted sugar kelp Laminaria saccharina communities above NeoPro, in the infralittoral zone (Lsac). Where NeoPro occurs on a rock or boulder slope and due to the very sheltered nature of the habitat, it is common to find a mud plain community where slope ends (CMU). 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 1 Occasional 21-40 %
Alcyonium digitatum 1 Occasional 41-60 %
Protanthea simplex 9 Common 61-80 %
Sabella pavonina 4 Occasional 61-80 %
Pomatoceros triqueter 12 Frequent 81-100 %
Balanus balanus 1 Occasional 21-40 %
Pagurus bernhardus 1 Occasional 41-60 %
Munida rugosa 2 Occasional 41-60 %
Buccinum undatum 1 Rare 41-60 %
Pododesmus patelliformis 6 Occasional 61-80 %
Neocrania anomala 9 Frequent 61-80 %
Asterias rubens 4 Occasional 61-80 %
Ophiothrix fragilis 4 Frequent 61-80 %
Psammechinus miliaris 4 Occasional 61-80 %
Echinus esculentus 3 Rare 61-80 %
Ciona intestinalis 5 Occasional 61-80 %
Corella parallelogramma 2 Occasional 41-60 %
Ascidia mentula 6 Occasional 61-80 %
Ascidia virginea 2 Rare 41-60 %
Polycarpa pomaria 2 Occasional 41-60 %
Corallinaceae 7 Common 61-80 %

Similar biotopes

CR.LCR.BrAs.AntAsH
This biotope is found under slightly more exposed conditons and tends to have a more diverse range of cnidarians and echinoderms than NeoPro.FS. In AntAsH, Antedon spp. are occasionally recorded, but they are absent in NeoPro.FS.

CR.LCR.BrAs.NeoPro.VS
This sub-biotope is found under similar physical conditions as NeoPro.FS, but is only found in stable, reduced salinity environments. The ascidian Dendrodoa grossularia is commonly recorded in this sub-biotope, but is absent in NeoPro.FS. However, the anemone Protanthea simplex is recorded in higher abundances in NeoPro.FS.

Photos

CR.LCR.BRAS.NeoPro.FS Neocrania anomala and Protanthea simplex on very wave-sheltered circalittoral rock, S of Gertrude Rock, Loch Duich. Sue Hiscock © JNCC
CR.LCR.BRAS.NeoPro.FS Neocrania anomala and Protanthea simplex on very wave-sheltered circalittoral rock, S of Gertrude Rock, Loch Duich. Sue Hiscock © JNCC

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