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Marine Habitat Classification

Description of biotope or habitat type

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   Mytilus edulis beds on sublittoral sediment

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed, Sheltered
Tidal streams Moderately strong (1-3 kn)
Substratum Mixed muddy sediment
Zone Circalittoral, Infralittoral
Depth Band 0-5 m, 5-10 m, 10-20 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 SS.SBR.SMus.MytSS <I>Mytilus edulis</I> beds on sublittoral sediment

  • Records used to define the biotope (core records)
  • Other records assigned to this biotope, marked as 'certain'
  • Other records assigned to this biotope, marked as 'uncertain'
  • Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat

Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.


Shallow sublittoral mixed sediment, in fully marine coastal habitats or sometimes in variable salinity conditions in the outer regions of estuaries, are characterised by beds of the common mussel Mytilus edulis. Other characterising infaunal species may include the amphipod Gammarus salinus and oligochaetes of the genus Tubificoides. The polychaetes Harmothoe spp., Kefersteinia cirrata and Heteromastus filiformis are also important. Epifaunal species in addition to the M. edulis include the whelks Nucella lapillus and Buccinum undatum, the common starfish Asterias rubens the spider crab Maja squinado and the anemone Urticina felina. Relatively few records are available for this biotope and it is possible that as more data is accumulated separate estuarine and fully marine sub-biotopes may be described. Further clarification may also be required with regard to the overlap between littoral and sublittoral mussel beds and with regard to mussel beds biotopes on hard substratum.


No situation data available.

Temporal variation

No temporal data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Anthozoa 2 Abundant 61-80 %
Urticina felina 7 Occasional 41-60 %
Actinothoe sphyrodeta 2 Occasional 21-40 %
Turbellaria 2 Frequent 81-100 %
Nemertea 6 Abundant 81-100 %
Harmothoe imbricata 2 Super abundant 61-80 %
Harmothoe impar 4 Abundant 81-100 %
Pholoe inornata 1 Common 61-80 %
Eteone longa 2 Abundant 61-80 %
Kefersteinia cirrata 2 Super abundant 81-100 %
Nereididae 1 81-100 %
Scoloplos armiger 1 Abundant 61-80 %
Capitella capitata 2 Common 61-80 %
Heteromastus filiformis 3 Common 61-80 %
Pomatoceros triqueter 2 Abundant 61-80 %
Oligochaeta 15 Abundant 81-100 %
Cirripedia 2 Common 61-80 %
Gammarus salinus 11 Super abundant 81-100 %
Paguridae 1 Occasional 21-40 %
Pagurus bernhardus 3 Frequent 21-40 %
Maja squinado 6 Frequent 41-60 %
Cancer pagurus 4 Occasional 41-60 %
Necora puber 2 Occasional 21-40 %
Crepidula fornicata 1 Occasional 21-40 %
Nucella lapillus 2 Common 61-80 %
Buccinum undatum 1 Occasional 21-40 %
Mytilus edulis 25 Super abundant 81-100 %
Mytilus edulis 60 Abundant 81-100 %
Flustra foliacea 1 Occasional 21-40 %
Asterias rubens 2 Abundant 61-80 %
Asterias rubens 3 Occasional 21-40 %
Pleuronectes platessa 2 Rare 21-40 %

Similar biotopes or habitat types

MytSS may be an extension of the littoral biotope Myt

AphPol may be separated from MytSS by the dominance of M. edulis in 'beds' rather than scattered individuals. Care must be taken with data to ensure juvenile spat recruitments are not classified as mussel beds.

Classification history of this biotope or habitat type

Classification version Code
97.06 IMX.MytV

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