JNCC is a statutory adviser to UK Government and devolved administrations
  Home  >  Marine  >  Marine Habitats  >  Habitat  >  Biotope classification


CR.HCR.XFa.ByErSp.Sag
Mixed turf of bryozoans and erect sponges with Sagartia elegans on tide-swept ciraclittoral rock

Full Hierarchy  >>  CR >>  CR.HCR >>  CR.HCR.XFa >>  CR.HCR.XFa.ByErSp >>  CR.HCR.XFa.ByErSp.Sag

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; boulder 
 Zone: Circalittoral - lower, Circalittoral - upper 
 Depth Band: 10-20 m, 20-30 m, 30-50 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.Sag  Mixed turf of bryozoans and erect sponges with Sagartia elegans on tide-swept ciraclittoral rock
Distribution of habitat CR.HCR.XFa.ByErSp.Sag Mixed turf of bryozoans and erect sponges with Sagartia elegans on tide-swept ciraclittoral 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 is typically found on wave-exposed circalittoral bedrock and boulders, on steep slopes and upper faces in moderate tidal streams. This species-rich biotope is characterised by a dense sponge, hydroid and bryozoan turf and frequent Alcyonium digitatum. There are frequently large growths of Cliona celata and Pachymatisma johnstonia. Other species present in this diverse sponge community include Polymastia boletiformis, Haliclona viscosa, Polymastia mamilliaris, Scypha ciliata, Hemimycale columella and Dysidea fragilis. Axinellid sponges such as Stelligera stuposa and Raspailia ramosa may be present in low abundance, and are usually more abundant in deeper water. A dense hydroid turf forms a significant part of this biotope, with tufts of large hydroids such as Nemertesia antennina and Nemertesia ramosa frequently recorded. Other hydroid turf component species include Halecium halecinum, Aglaophenia tubulifera and Abietinaria abietina. Anemones are also well represented, with species such as Urticina felina, Sagartia elegans and Metridium senile recorded. The cup coral Caryophyllia smithii and the anemone Corynactis viridis are also frequently seen. The bryozoan turf is composed predominantly of Alcyonidium diaphanum and Flustra foliacea, whilst crustose species such as Parasmittina trispinosa contribute to a lesser extent. The delicate Bugula plumosa may also be present. There is a significant echinoderm component in this biotope. Species such as the starfish Asterias rubens, Henricia oculata, Marthasterias glacialis and Luidia ciliaris, the sea urchin Echinus esculentus and the crinoid Antedon bifida are all regularly recorded. Other species which may be observed include the top shell Calliostoma zizyphinium, the colonial ascidian Clavelina lepadiformis and the barnacle Balanus crenatus. The crab Cancer pagurus is typically found under boulders. This variant has been recorded from from various sites including Pembrokeshire, the Calf of Man and the west coast of Ireland.

Situation

Dense kelp forests containing L. hyperborea and S. polyschides are typically found above ByErSp.Sag.

Temporal variation

Not known

Similar biotopes

CR.HCR.XFa.ByErSp.EunThis biotope occurs under similar conditions and depths as ByErSp.Sag. A diverse group of sponges, hydroids and bryozoans are found in both biotopes, but it is the frequently recorded Eunicella verrucosa and the occasional presence of Parazoanthus axinellae and Isozoanthus sulcatus that distinguishes it from ByErSp.Sag.
CR.HCR.XFa.ByErSp.DysActThis biotope occurs under similar wave-exposure conditions with stronger tides than ByErSp.Sag. Also, ByErSp.DysAct is found at slightly shallower depths than ByErSp.Sag. Both biotopes have similar suites of species but distinct geographical distributions: ByErSp.DysAct only tends to be found off Wales and Lundy whereas ByErSp.Sag is usually found off the west coast of Ireland.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity
Scypha ciliata O 1
Pachymatisma johnstonia O 1
Polymastia boletiformis F 2
Polymastia mamillaris F 1
Stelligera stuposa O 1
Cliona celata F 4
Hemimycale columella O 1
Haliclona viscosa O 2
Dysidea fragilis O 1
Halecium halecinum F 2
Abietinaria abietina O 1
Nemertesia antennina F 5
Nemertesia ramosa F 3
Aglaophenia tubulifera F 1
Alcyonium digitatum F 6
Urticina felina O 3
Metridium senile F 1
Sagartia elegans F 2
Corynactis viridis F 2
Caryophyllia smithii F 3
Balanus crenatus F 2
Cancer pagurus O 1
Calliostoma zizyphinum O 3
Alcyonidium diaphanum O 2
Flustra foliacea F 2
Bugula plumosa O 1
Parasmittina trispinosa F 1
Antedon bifida F 2
Luidia ciliaris O 2
Henricia oculata O 3
Asterias rubens O 3
Marthasterias glacialis O 2
Echinus esculentus O 3
Clavelina lepadiformis O 2

Example photographs of biotope


Overhanging rock with Pachymatisma, other sponges and Alcyonium, Rathlin Island, Rohan Holt, © JNCC
Click on an image for a larger view


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