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Marine Habitat Classification


Description of biotope or habitat type

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   Corynactis viridis and a mixed turf of crisiids, Bugula, Scrupocellaria, and Cellaria on moderately tide-swept exposed circalittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Very exposed, Exposed, Moderately exposed
Tidal streams Strong (3-6 kn), Moderately strong (1-3 kn)
Substratum Bedrock; very large boulders
Zone Circalittoral - lower, Circalittoral - upper
Depth Band 10-20 m, 20-30 m
Other Features Often on vertical or steep rock

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.HCR.XFa.CvirCri <I>Corynactis viridis</I> and a mixed turf of crisiids, <I>Bugula</I>, <I>Scrupocellaria</I>, and <I>Cellaria</I> on moderately tide-swept exposed 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 biotope typically occurs on wave-exposed, vertical or steep, circalittoral bedrock or large boulders, usually subject to moderate or strong tidal streams. It is characterised by dense aggregations of the anemone Corynactis viridis and the cup coral Caryophyllia smithii intermixed with a short bryozoan turf of one or more Crisia spp., Scrupocellaria spp., Bugula spp. and Cellaria spp. Occasionally, this turf obscures the underlying C. virdis and C. smithii. Cushion and encrusting sponges, particularly Pachymatisma johnstonia, Cliona celata, Esperiopsis fucorum and Dysidea fragilis, are present in moderate amounts at many sites. The axinellid sponges Stelligera spp. and Raspailia spp. are less frequently recorded. Clumps of large hydroids such as Nemertesia antennina and Nemertesia ramosa as well as the soft coral Alcyonium digitatum and the bryozoan Alcyonidium diaphanum may be found covering the hard substratum. The anemones Actinothoe sphyrodeta and Sagartia elegans are typically present in low numbers, while the hard `coral' Pentapora foliacea is also occasionally observed. The most frequently recorded echinoderms are Marthasterias glacialis and Asterias rubens, although other species such as Echinus esculentus may also be seen. The rocky substratum may have a patchy covering of encrusting red seaweeds/algae. The crabs Necora puber and Cancer pagurus may be seen in crevices or under overhangs. This biotope is regularly recorded around south west England and Wales, often on vertical rock faces.

Situation

Due to its wave-exposed nature, kelp park and forest biotopes (LhypR and Ala) are commonly found in the infralittoral zone shallower than this biotope, and feature species such as Laminaria hyperborea, Sacchoriza polyschides and Alaria esculenta.

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
Porifera 1 Occasional 41-60 %
Pachymatisma johnstonia 2 Occasional 61-80 %
Cliona celata 5 Occasional 81-100 %
Esperiopsis fucorum 1 Occasional 41-60 %
Raspailia ramosa 1 Occasional 41-60 %
Dysidea fragilis 2 Occasional 41-60 %
Nemertesia antennina 3 Common 61-80 %
Nemertesia ramosa 2 Occasional 41-60 %
Alcyonium digitatum 10 Common 81-100 %
Sagartia elegans 1 Occasional 41-60 %
Actinothoe sphyrodeta 3 Occasional 61-80 %
Corynactis viridis 9 Common 81-100 %
Caryophyllia smithii 8 Frequent 81-100 %
Cancer pagurus 1 Rare 41-60 %
Necora puber 2 Occasional 61-80 %
Bryozoa 3 Frequent 61-80 %
Crisiidae 4 Common 61-80 %
Alcyonidium diaphanum 2 Occasional 41-60 %
Scrupocellaria 1 Common 21-40 %
Cellaria sinuosa 1 Frequent 21-40 %
Pentapora foliacea 2 Occasional 41-60 %
Asterias rubens 4 Frequent 61-80 %
Marthasterias glacialis 4 Frequent 81-100 %
Echinus esculentus 2 Occasional 61-80 %
Corallinaceae 1 Occasional 41-60 %

Similar biotopes

CR.HCR.XFa.ByErSp.Sag
This variant is found on slightly less exposed coasts and in slightly weaker tides than CvirCri. In addition, ByErSp.Sag is characterised by a greater diversity of sponges, hydroids and anemones and also has small amounts of polyclinid ascidians, which in CvirCri are rare. ByErSp.Sag may sometimes be found below CvirCri.

CR.MCR.EcCr.CarSp.PenPcom
This variant is subject to weaker tides than CvirCri, but is found on similar wave-exposed upward-facing bedrock. The general appearance of CarSp.PenPcom is of a fairly sparse but diverse fauna and it lacks the bryozoan turf of CvirCri, having larger amounts of brittle and encrusting bryozoans such as Porella compressa and Parasmittina trispinosa.

CR.HCR.XFa.ByErSp.Eun
This variant occurs under similar conditions as CvirCri. It is characterised by the presence of Eunicella verrucosa and Alcyonium glomeratum, in combination with diverse sponges and hydroids. It also contains a much wider range of ascidians than CvirCri.

CR.HCR.XFa.ByErSp.DysAct
This sub-biotope occurs on similar wave-exposed bedrock and boulders as CvirCri, but is found in slightly stronger tidal streams. The sponge D. fragilis and the anemone A. sphyrodeta are present in much higher abundances than in CvirCri. A more diverse range of ascidians is present in ByErSp.DysAct.

Biotope history

Classification Habitat code
97.06 CR.ECR.EFa.CorCri

Photos

CR.HCR.XFA.CvirCri Corynactis viridis and a mixed turf of crisiids, Bugula, Scrupocellaria, and Cellaria on moderately tide-swept exposed circalittoral rock, Top of Hand Deeps reef, Plymouth. Paul Brazier © JNCC
CR.HCR.XFA.CvirCri Corynactis viridis and a mixed turf of crisiids, Bugula, Scrupocellaria, and Cellaria on moderately tide-swept exposed circalittoral rock, Top of Hand Deeps reef, Plymouth. Paul Brazier © JNCC
CR.HCR.XFA.CvirCri Corynactis viridis and a mixed turf of crisiids, Bugula, Scrupocellaria, and Cellaria on moderately tide-swept exposed circalittoral rock, W of Wagland Reef, Coverack. Eleanor Murray © JNCC
CR.HCR.XFA.CvirCri Corynactis viridis and a mixed turf of crisiids, Bugula, Scrupocellaria, and Cellaria on moderately tide-swept exposed circalittoral rock, W of Wagland Reef, Coverack. Eleanor Murray © JNCC
CR.HCR.XFA.CvirCri Corynactis viridis and a mixed turf of crisiids, Bugula, Scrupocellaria, and Cellaria on moderately tide-swept exposed circalittoral rock, Near Seals Rock, East coast of Lundy. Keith Hiscock © JNCC
CR.HCR.XFA.CvirCri Corynactis viridis and a mixed turf of crisiids, Bugula, Scrupocellaria, and Cellaria on moderately tide-swept exposed circalittoral rock, Near Seals Rock, East coast of Lundy. Keith Hiscock © JNCC

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