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SS.SMu.CFiMu.SpnMeg
Seapens and burrowing megafauna in circalittoral fine mud

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Habitat (physical) description

Distribution

 Salinity: Full (30-35 ppt), Variable (18-35 ppt) 
 Wave exposure: Moderately exposed, Sheltered, Very sheltered, Extremely sheltered 
 Tidal streams: Weak (>1 kn), Very weak (negligible) 
 Substratum: Mud 
 Zone: Circalittoral 
 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.

Previous code

This biotope occurred in previous versions of the classification as:
CMU.SpMeg - Version: 97.06
CMU.SpNep - Version: 96.7

Distribution of habitat SS.SMu.CFiMu.SpnMeg  Seapens and burrowing megafauna in circalittoral fine mud
Distribution of habitat SS.SMu.CFiMu.SpnMeg Seapens and burrowing megafauna in circalittoral fine mud, 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

Plains of fine mud at depths greater than about 15 m may be heavily bioturbated by burrowing megafauna; burrows and mounds may form a prominent feature of the sediment surface with conspicuous populations of seapens, typically Virgularia mirabilis and Pennatula phosphorea. The burrowing crustacea present typically include Nephrops norvegicus, which is frequently recorded from surface observations although grab sampling may fail to sample this species. Indeed, some forms of sampling may also fail to indicate seapens as characterising species. This biotope also seems to occur in deep offshore waters in the North Sea, where densities of Nephrops norvegicus may reach 68 per 10 m-2 (see Dyer et al. 1982, 1983), and the Irish Sea. The burrowing anemone Cerianthus lloydii and the ubiquitous epibenthic scavengers Asterias rubens, Pagurus bernhardus and Liocarcinus depurator are present in low numbers in this biotope whilst the brittlestars Ophiura albida and Ophiura ophiura are sometimes present, but are much more common in slightly coarser sediments. Low numbers of the anemone Pachycerianthus multiplicatus may also be found, and this species, which is scarce in the UK, appears to be restricted to this habitat (Plaza & Sanderson 1997). The infauna may contain significant populations of the polychaetes Pholoe spp., Glycera spp., Nephtys spp., spionids, Pectinaria belgica and Terebellides stroemi, the bivalves Nucula sulcata, Corbula gibba and Thyasira flexuosa, and the echinoderm Brissopsis lyrifera.

Situation

These soft mud habitats occur extensively throughout the more sheltered basins of sealochs and voes and are present in quite shallow depths (as little as 15 m) in these areas probably because they are very sheltered from wave action.

Temporal variation

No temporal data available.

Similar biotopes

SS.SMu.IFiMu.PhiVirPhiVir is superficially similar to SpnMeg but is found in shallower, less thermally stable waters and lacks the large burrowing species and the sea pen Pennatula phosphorea.
SS.SMu.CFiMu.SpnMeg.FunIn the deeper fjordic lochs which are protected by an entrance sill, the tall seapen Funiculina quadrangularis may also be present and distinguishes SpnMeg.Fun from SpnMeg.
SS.SMu.CFiMu.BlyrAchiSpnMeg is closely allied to BriAchi and may show strong similarities in infaunal species composition. However, epifaunally they differ in the abundance of characterising species such as Pennatula phosphorea and Amphiura spp.
SS.SMu.CFiMu.MegMaxMegMax is found in similar habitats but has reduced numbers of seapens and a wider range of megafauna.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity Abundance (no.2)
Hydractinia echinata O 1
Virgularia mirabilis F 20
Pennatula phosphorea F 6
Cerianthus lloydii O 13
Chaetopterus variopedatus O 2
Nephrops norvegicus F 18
Pagurus bernhardus O 5
Liocarcinus depurator O 8
Turritella communis F 3
Asterias rubens O 8
Amphiura chiajei C 2

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