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IR.HIR.KSed.XKHal
Halidrys siliquosa and mixed kelps on tide-swept infralittoral rock with coarse sediment

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Habitat (physical) description

Distribution

 Salinity: Full (30-35 ppt) 
 Wave exposure: Moderately exposed 
 Tidal streams: Moderately strong (1-3 kn), Weak (>1 kn) 
 Substratum: Bedrock, boulders or cobbles with coarse sediment 
 Zone: Infralittoral 
 Depth Band: 0-5 m, 5-10 m, 10-20 m 
 Other Features: Sediment abrasion 

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.HalXK - Version: 97.06
MIR.HalXK.Ft - Version: 96.7
MIR.HalXK.Pk - Version: 96.7

Distribution of habitat IR.HIR.KSed.XKHal  Halidrys siliquosa and mixed kelps on tide-swept infralittoral rock with coarse sediment
Distribution of habitat IR.HIR.KSed.XKHal Halidrys siliquosa and mixed kelps on tide-swept infralittoral rock with coarse sediment, 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

Tide-swept boulders and cobbles, often with a mobile component to the substrata (pebbles, gravel and sand), characterised by dense stands of the brown seaweed Halidrys siliquosa. It is can be mixed with the foliose brown seaweed Dictyota dichotoma and kelp such as Laminaria saccharina and Laminaria hyperborea. Below the canopy is an undergrowth of red seaweeds that are tolerant of sand-scour such as Phyllophora crispa, Phyllophora pseudoceranoides, Rhodomela confervoides, Corallina officinalis and Chondrus crispus. Other red seaweeds such as Plocamium cartilagineum, Calliblepharis ciliata, Cryptopleura ramosa, Delesseria sanguinea, Heterosiphonia plumosa, Dilsea carnosa, Hypoglossum hypoglossoides and Brongniartella byssoides may be locally abundant, particularly in the summer months. There may be a rich epibiota on H. siliquosa, including the hydroid Aglaophenia pluma, ascidians such as Botryllus schlosseri. There is generally a sparse faunal component colonising the boulders and cobbles, comprising the tube-building polychaete Pomatoceros triqueter, the crab Cancer pagurus, the starfish Asterias rubens, the gastropod Gibbula cineraria and the sea anthozoan Urticina felina. The bryozoan Electra pilosa can form colonies on the kelp.

Situation

XKHal can occur below the tide-swept Laminaria digitata zone of the sublittoral fringe bedrock or boulders (LdigT). Less stable substrata of boulders, cobbles or pebbles may support kelp and Chorda filum in the shallows (LsacChoR) or dense ephemeral seaweeds (EphR). Sand-influenced rocky outcrops in deeper water may support a Flustra foliacea community (FluCoAs). This biotope is widespread and is found on the open coast in Wales, the south-west and the English Channel as well as more sheltered tidal rapids in the Scottish sealochs. It can form extensive forests or parks in certain areas (Dorset, Sarns). In Wales, the south-west and west of England the red seaweeds Spyridia filamentosa and Halarachnion ligulatum and brown seaweeds Dictyopteris membranacea and Taonia atomaria are frequent. In Scotland, kelp occur at a greater proportion of sites, solitary ascidians such as Ascidiella spp. are more common and the featherstar Antedon bifida and brittlestars Ophiothrix fragilis are found.

Temporal variation

Higher diversity of red seaweeds during the summer.

Similar biotopes

IR.HIR.KSed.XKScrRThis biotope is distinguished from XKHal by its greater scour.
IR.MIR.KT.XKTThis biotope is distinguished from XKHal by occurring at more sheltered shores and by the occurrence of species like the urchin Echinus esculentus, the brittlestar Ophiothrix fragilis and the crab Carcinus maenas (all typical abundance of Occasional).
IR.MIR.KT.XKTXUsually at more sheltered shores with a mixed substratum, variable salinity and stronger tidal streams. Species like the urchin E. esculentus, the brittlestar Ophiothrix fragilis and the crap C. maenas and encrusting red algae Lithothamnion graciale (Frequent) occurs in this biotope.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity
Aglaophenia pluma F 1
Urticina felina O 1
Pomatoceros triqueter F 3
Cancer pagurus O 1
Gibbula cineraria O 2
Electra pilosa F 2
Asterias rubens F 3
Botryllus schlosseri F 3
Corallinaceae F 3
Corallina officinalis O 1
Calliblepharis ciliata O 2
Dilsea carnosa O 2
Chondrus crispus O 2
Phyllophora crispa O 1
Phyllophora pseudoceranoides F 2
Plocamium cartilagineum F 4
Heterosiphonia plumosa F 3
Cryptopleura ramosa O 2
Hypoglossum hypoglossoides O 1
Brongniartella byssoides F 3
Rhodomela confervoides O 2
Dictyota dichotoma F 4
Laminaria hyperborea F 1
Laminaria saccharina O 2
Halidrys siliquosa C 15

Example photographs of biotope


Halidrys siliquosa on sand and cobble sea bed, Off Churn Rock, Farnes, Teresa Bennett, © JNCC Close up of Halidrys with sponge and Anemonia, Tob Valasay rapids, Tob Valasay, Lewis., Robert Irving, © JNCC Halidrys and Dilsea, Bun Sruth, Western Isles, ANON, © 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