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IR.HIR.KSed.ProtAhn
Polyides rotundus, Ahnfeltia plicata and Chondrus crispus on sand-covered infralittoral rock

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Habitat (physical) description

Distribution

 Salinity: Full (30-35 ppt) 
 Wave exposure: Exposed, Moderately exposed 
 Tidal streams: Moderately strong (1-3 kn), Weak (>1 kn) 
 Substratum: Bedrock, cobbles and pebbles with mobile sand 
 Zone: Infralittoral 
 Depth Band: 5-10 m 
 Other Features: Sand-covered 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.

Previous code

This biotope occurred in previous versions of the classification as:
MIR.PolAhn - Version: 97.06

Distribution of habitat IR.HIR.KSed.ProtAhn  Polyides rotundus, Ahnfeltia plicata and Chondrus crispus on sand-covered infralittoral rock
Distribution of habitat IR.HIR.KSed.ProtAhn Polyides rotundus, Ahnfeltia plicata and Chondrus crispus on sand-covered infralittoral 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

Low-lying rock surrounded by mobile sand and often subject to burying by the sand, with a turf of resilient red seaweeds Chondrus crispus, Polyides rotundus and Ahnfeltia plicata typically protruding through the sand on the upper surfaces of the rock. Other scour-tolerant seaweeds include Rhodomela confervoides, Phyllophora pseudoceranoides, Phyllophora crispa, Furcellaria lumbricalis, Gracilaria gracilis, Ceramium rubrum, Plocamium cartilagineum, Heterosiphonia plumosa, Cryptopleura ramosa and Dilsea carnosa. Coralline crusts typically cover the rock, while scattered individuals of the brown seaweeds Halidrys siliquosa, Cladostephus spongiosus, Dictyota dichotoma and Laminaria saccharina can be present. The large anthozoan Urticina felina can occur in this biotope but there are few other conspicuous animals.

Situation

This biotope occurs on shallow sand-covered rock, often below bedrock and boulders supporting kelp forest, which is above the effect of, sand scour (Lhyp) or abutting sand-scoured kelp on bedrock (XKScrR). It may also be found adjacent to the shallow kelp and Chorda filum biotope (LsacChoR) and similarly can be surrounded by a variety of sediment biotopes.

Temporal variation

Unknown.

Similar biotopes

IR.HIR.KSed.XKHalLack of large boulders or prominent bedrock in ProtAhn prevents dominance by H. siliquosa or kelps.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity
Urticina felina O 1
Ahnfeltia plicata F 6
Corallinaceae F 9
Dilsea carnosa O 6
Furcellaria lumbricalis O 4
Chondrus crispus F 15
Phyllophora crispa O 3
Phyllophora pseudoceranoides F 3
Polyides rotundus F 10
Gracilaria gracilis F 1
Plocamium cartilagineum O 2
Ceramium nodulosum F 1
Heterosiphonia plumosa F 3
Cryptopleura ramosa O 3
Rhodomela confervoides F 3
Cladostephus spongiosus O 1
Dictyota dichotoma O 2
Laminaria saccharina O 4
Halidrys siliquosa O 1
Ulva O 1
Ulva O 1

Example photographs of biotope

No characteristic photos currently available. If you are able to provide a photograph of this biotope please contact .


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