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CR.MCR.SfR.Pid
Piddocks with a sparse associated fauna in sublittoral very soft chalk or clay

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Habitat (physical) description

Distribution

 Salinity: Full (30-35 ppt) 
 Wave exposure: Moderately exposed 
 Tidal streams: Moderately strong (1-3 kn) 
 Substratum: Bedrock 
 Zone: Circalittoral 
 Depth Band: 5-10 m, 10-20 m 
 Other Features: Soft rock: chalk or clay. Often with vertical faces. 

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:
CR.MCR.SfR.Pid - Version: 97.06

Distribution of habitat CR.MCR.SfR.Pid  Piddocks with a sparse associated fauna in sublittoral very soft chalk or clay
Distribution of habitat CR.MCR.SfR.Pid Piddocks with a sparse associated fauna in sublittoral very soft chalk or clay, 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 biotope occurs on circalittoral soft rock, such as soft chalk or clay, most often in moderately exposed tide-swept conditions. As soft chalk and firm clay are often too soft for sessile filter-feeding animals to attach and thrive in large numbers, an extremely impoverished epifauna results on upward-facing surfaces, although vertical faces may be somewhat richer. The rock is sufficiently soft to be bored by bivalves. Species vary with location, but Pholas dactylus is the most widespread borer and may be abundant. Other species present may include the sponges Dysidea fragilis and Suberites carnosus and the polychaete Bispira volutacornis. Foliose red algae may be present on the harder, more stable areas of rock. Mobile fauna often include the crabs Necora puber and Cancer pagurus.

Situation

Subtidal chalk reefs or clay outcrops, mostly known from south-east England.

Temporal variation

Not known.

Similar biotopes

IR.MIR.KR.Ldig.PidThis biotope is found on sublittoral fringe soft rock on moderately exposed coasts. It is characterised by boring bivalves and the kelp Laminaria digitata.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity
Suberites carnosus F 2
Bispira volutacornis O 2
Necora puber R 1
Pholas dactylus C 83
Rhodophycota O 4

Example photographs of biotope

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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