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Marine Habitat Classification


Description of biotope or habitat type

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   Bryozoan turf and erect sponges on tide-swept circalittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Extremely exposed, Very exposed, Exposed, Moderately exposed
Tidal streams Strong (3-6 kn), Moderately strong (1-3 kn)
Substratum Bedrock; boulder
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 Bryozoan turf and erect sponges on tide-swept 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 is typically found on wave-exposed circalittoral bedrock or boulders subject to tidal streams ranging from moderately strong to strong. It often has a thin layer of silt covering the seabed, and is characterised by a bryozoan/hydroid turf with erect sponges. Typical bryozoans to be found include crisiids, Alcyonidium diaphanum, Flustra foliacea, Pentapora foliacea, Bugula plumosa and Bugula flabellata, while typical hydroids include Nemertesia antennina, Nemertesia ramosa and Halecium halecinum. The soft coral Alcyonium digitatum is frequently recorded on the tops of boulders and rocky outcrops. Characteristic erect sponges include Raspailia ramosa, Stelligera stuposa and Stelligera rigida; other sponges present include Cliona celata, Dysidea fragilis, Pachymatisma johnstonia, Polymastia boletiformis, Hemimycale columella, Esperiopsis fucorum, Polymastia mamillaris and Tethya aurantium. Other species present include Caryophylia smithii, Actinothoe sphyrodeta, Corynactis viridis, Urticina felina, Balanus crenatus, Asterias rubens, Marthasterias glacialis, Henricia oculata, Echinus esculentus, Clavelina lepadiformis, Calliostoma zizyphinum and Necora puber. Three variants of this biotope have been described, but all are characterised by a bryozoan turf with erect sponges. ByErSp.Eun is found primarily on circalittoral bedrock and is dominated by the seafan Eunicella verrucosa. ByErSp.DysAct is found under slightly stronger tide-swept conditions, and is characterised particularly by the sponge D. fragilis and the anemone A. sphyrodeta. Finally ByErSp.Sag is characterised by the anemone Sagartia elegans.

Situation

No situation data available.

Temporal variation

No temporal variation data available.

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Pachymatisma johnstonia 2 Occasional 61-80 %
Tethya aurantium 1 Occasional 41-60 %
Polymastia boletiformis 2 Frequent 61-80 %
Polymastia mamillaris 1 Occasional 41-60 %
Stelligera rigida 1 Occasional 41-60 %
Stelligera stuposa 2 Occasional 41-60 %
Cliona celata 4 Occasional 81-100 %
Esperiopsis fucorum 2 Frequent 41-60 %
Hemimycale columella 2 Occasional 61-80 %
Raspailia ramosa 2 Occasional 61-80 %
Dysidea fragilis 3 Frequent 61-80 %
Halecium halecinum 1 Frequent 41-60 %
Nemertesia antennina 4 Frequent 81-100 %
Nemertesia ramosa 2 Occasional 61-80 %
Alcyonium digitatum 5 Frequent 81-100 %
Urticina felina 1 Occasional 41-60 %
Actinothoe sphyrodeta 2 Occasional 61-80 %
Corynactis viridis 2 Frequent 41-60 %
Caryophyllia smithii 4 Frequent 61-80 %
Balanus crenatus 2 Occasional 21-40 %
Necora puber 1 Occasional 41-60 %
Calliostoma zizyphinum 2 Occasional 41-60 %
Crisiidae 1 Frequent 41-60 %
Alcyonidium diaphanum 3 Frequent 61-80 %
Flustra foliacea 2 Frequent 41-60 %
Bugula flabellata 1 Occasional 41-60 %
Bugula plumosa 2 Frequent 41-60 %
Pentapora foliacea 1 Occasional 41-60 %
Henricia oculata 1 Occasional 41-60 %
Asterias rubens 3 Frequent 61-80 %
Marthasterias glacialis 1 Occasional 41-60 %
Echinus esculentus 2 Occasional 61-80 %
Clavelina lepadiformis 2 Occasional 61-80 %

Similar biotopes

Not applicable or unknown.

Photos

CR.HCR.XFA.ByErSp Bryozoan turf and erect sponges on tide-swept circalittoral rock, Sligneach Mor, Sunart. Rohan Holt © JNCC
CR.HCR.XFA.ByErSp Bryozoan turf and erect sponges on tide-swept circalittoral rock, Sligneach Mor, Sunart. Rohan Holt © JNCC

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