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Marine Habitat Classification


Description of biotope or habitat type

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   Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock


Habitat (physical) description

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.

Distribution of habitat CR.HCR.XFa.ByErSp.Eun <I>Eunicella verrucosa</I> and <I>Pentapora foliacea</I> on wave-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 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

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 %
Polymastia boletiformis 1 Occasional 41-60 %
Stelligera stuposa 2 Occasional 41-60 %
Cliona celata 5 Frequent 81-100 %
Axinella dissimilis 2 Occasional 61-80 %
Raspailia hispida 2 Occasional 61-80 %
Raspailia ramosa 2 Occasional 61-80 %
Dysidea fragilis 1 Occasional 41-60 %
Nemertesia antennina 5 Frequent 81-100 %
Nemertesia ramosa 4 Occasional 61-80 %
Alcyonium digitatum 6 Frequent 81-100 %
Alcyonium glomeratum 2 Occasional 41-60 %
Eunicella verrucosa 7 Frequent 81-100 %
Parazoanthus axinellae 1 Occasional 41-60 %
Actinothoe sphyrodeta 2 Occasional 61-80 %
Caryophyllia smithii 7 Common 81-100 %
Crisiidae 1 Occasional 41-60 %
Alcyonidium diaphanum 4 Frequent 61-80 %
Bugula plumosa 1 Common 41-60 %
Pentapora foliacea 7 Frequent 81-100 %
Marthasterias glacialis 4 Frequent 61-80 %
Echinus esculentus 3 Occasional 61-80 %
Holothuria forskali 3 Frequent 41-60 %
Clavelina lepadiformis 2 Occasional 41-60 %
Stolonica socialis 2 Common 41-60 %

Similar biotopes

CR.MCR.EcCr.CarSp.PenPcom
This 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.Sag
This 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.PhaAxi
This 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.CvirCri
This 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.

Biotope history

Classification Habitat code
97.06 CR.MCR.XFa.ErSEun

Photos

CR.HCR.XFA.ByErSp.Eun Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock, 2 miles S of Plymouth Breakwater. Rohan Holt © JNCC
CR.HCR.XFA.ByErSp.Eun Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock, 2 miles S of Plymouth Breakwater. Rohan Holt © JNCC
CR.HCR.XFA.ByErSp.Eun Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock, Offshore SE of Nare Point, Coverack. Francis Bunker © JNCC
CR.HCR.XFA.ByErSp.Eun Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock, Offshore SE of Nare Point, Coverack. Francis Bunker © JNCC
CR.HCR.XFA.ByErSp.Eun Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock, Offshore Pencra Head, Coverack. Rohan Holt © JNCC
CR.HCR.XFA.ByErSp.Eun Eunicella verrucosa and Pentapora foliacea on wave-exposed circalittoral rock, Offshore Pencra Head, Coverack. Rohan Holt © JNCC

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