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CR.HCR.XFa.ByErSp.Eun
Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock

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Habitat (physical) description

Distribution

 Salinity: Full (30-35 ppt) 
 Wave exposure: Extremely exposed, Very exposed, Exposed, Moderately exposed 
 Tidal streams: Moderately strong (1-3 kn) 
 Substratum: Bedrock 
 Zone: Circalittoral - lower, Circalittoral - upper 
 Depth Band: 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.

Previous code

This biotope occurred in previous versions of the classification as:
CR.MCR.XFa.ErSEun - Version: 97.06

Distribution of habitat CR.HCR.XFa.ByErSp.Eun  Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock
Distribution of habitat CR.HCR.XFa.ByErSp.Eun Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock, based on records on the UK Marine Recorder database and EUSeaMap. Red dots represent records on which the biotope is based. Blue dots show other certain records, black dots show records tentatively assigned to this biotope. Yellow areas show level 2 and 3 sublittoral and deep-sea habitats prediced by EUSeaMap within UK waters.

Biotope description

This variant typically occurs on wave-exposed, steep, circalittoral bedrock, boulder slopes and outcrops, subject to varying tidal streams. This silty variant contains a diverse faunal community, dominated by the seafan Eunicella verrucosa, the bryozoan Pentapora foliacea and the cup coral Caryophyllia smithii. There are frequently numerous Alcyonium digitatum, and these may become locally abundant under more tide-swept conditions. Alcyonium glomeratum may also be present. A diverse sponge community is usually present, including numerous erect sponges; species present include Cliona celata, Raspailia ramosa, Raspailia hispida, Axinella dissimilis, Stelligera stuposa, Dysidea fragilis and Polymastia boletiformis. Homaxinella subdola may be present in the south west. A hydroid/bryozoan turf may develop in the understorey of this rich sponge assemblage, with species such as Nemertesia antennina, Nemertesia ramosa, crisiids, Alcyonidium diaphanum and Bugula plumosa. The sea cucumber Holothuria forskali may be locally abundant, feeding on the silty deposits on the rock surface. Other echinoderms encountered include the starfish Marthasterias glacialis and the urchin Echinus esculentus. Other fauna includes aggregations of colonial ascidians Clavelina lepadiformis and Stolonica socialis. Anemones such as Actinothoe sphyrodeta and Parazoanthus axinellae may be seen dotted across the rock surface. This biotope is present in south west England and Wales.

Situation

This biotope is commonly found on rocky outcrops, surrounded by coarse sediment. This may be in the form of shelly gravel or muddy gravel, supporting Urticina felina, Cerianthus lloydi and Neopentadactyla mixta. Above ByErSp.Eun, dense kelp forest containing Saccorhiza polyschides is usually found.

Temporal variation

Not known

Similar biotopes

CR.MCR.EcCr.CarSp.PenPcomThis biotope occurs under similar wave-exposure conditions as ByErSp.Eun but is found in sites subject to only very weak tidal streams. ByErSp.Eun has a more diverse array of sponges (including erect sponges) and 'turf-forming' bryozoans.
CR.HCR.XFa.ByErSp.SagThis biotope occurs under similar conditions and depths as ByErSp.Eun. A diverse group of sponges, hydroids and bryozoans are found in both biotopes, but it is the absence of E. verrucosa and species such as Parazoanthus axinellae and Isozoanthus sulcatus that distinguishes ByErSp.Sag from ByErSp.Eun.
CR.HCR.DpSp.PhaAxiThis biotope occurs under similar wave-exposure conditions as ByErSp.Eun but is found in sites subject to only very weak tidal streams and much deeper with a mean depth range of 32m-37m. Although E. verrucosa is present in this biotope, it is not as abundant as in ByErSp.Eun. It is the presence of significant numbers of axinellid sponges that distinguishes this biotope.
CR.HCR.XFa.CvirCriThis biotope occurs under similar conditions as ByErSp.Eun, but may occur at slightly deeper water depths. CvirCri lacks E. verrucosa but has a similar bryozoan and hydroid turf to ByErSp.Eun. The latter does have a slightly more diverse range of sponges and ascidians than CvirCri.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity
Porifera O 1
Polymastia boletiformis O 1
Stelligera stuposa O 2
Cliona celata F 5
Axinella dissimilis O 2
Raspailia hispida O 2
Raspailia ramosa O 2
Dysidea fragilis O 1
Nemertesia antennina F 5
Nemertesia ramosa O 4
Alcyonium digitatum F 6
Alcyonium glomeratum O 2
Eunicella verrucosa F 7
Parazoanthus axinellae O 1
Actinothoe sphyrodeta O 2
Caryophyllia smithii C 7
Crisiidae O 1
Alcyonidium diaphanum F 4
Bugula plumosa C 1
Pentapora foliacea F 7
Marthasterias glacialis F 4
Echinus esculentus O 3
Holothuria forskali F 3
Clavelina lepadiformis O 2
Stolonica socialis C 2

Example photographs of biotope


Dense Alcyonium and Eunicella, 2 miles S of Plymouth Breakwater., Rohan Holt, © JNCC Forest of Eunicella verrucosa, Offshore SE of Nare Point, Coverack., Francis Bunker, © JNCC Forest of Eunicella with Alcyonium, erect sponges and hydroids, Offshore Pencra Head, Coverack., Rohan Holt, © JNCC
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Version 15.03 of the classification adds a deep-sea section to version 04.05; therefore superseding version 04.05, 97.06 and 03.02.

This online classification should be cited as:

JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed]. Available from: jncc.defra.gov.uk/MarineHabitatClassification

Information from the shallower section (up to sublittoral sediment, taken from Version 04.05) be cited as the report accompanying Version 04.05, as follows:

CONNOR, D.W., J.H. ALLEN, N.GOLDING, K.L.HOWELL, L.M. LIEBERKNECHT, K.O. NORTHEN AND J.B. REKER (2004) The Marine Habitat Classification for Britain and Ireland Version 04.05. In: JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed].
Available from: jncc.defra.gov.uk/MarineHabitatClassification
ISBN 1 861 07561 8


Information from the deep-sea section (added in March 2015) should be cited as the report accompanying the deep-sea section, as follows:

PARRY, M.E.V., K.L. HOWELL, B.E. NARAYANASWAMY, B.J. BETT, D.O.B. JONES, D.J. HUGHES, N. PIECHAUD, T.D. NICKELL, H. ELLWOOD, N. ASKEW, C. JENKINS and E. MANCA (2015) A Deep-sea Section for the Marine Habitat Classification of Britain and Ireland. JNCC report 530. In: JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed].
Available from: jncc.defra.gov.uk/MarineHabitatClassification
ISSN 0963 8901