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Marine Habitat Classification

Description of biotope or habitat type

To understand more about what this page is describing, see How to use the classification. See also How to cite.

   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

Biotope origin

Derived using data from Various
Faunal group Epifauna/infauna

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., Psamathe fusca 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 regarding the overlap between littoral and sublittoral mussel beds and regarding 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
Mytilus edulis 60 Abundant 81-100%
Mytilus edulis 25 Super abundant 81-100%
Oligochaeta 15 Abundant 81-100%
Gammarus salinus 11 Super abundant 81-100%
Urticina felina 7 Occasional 41-60%
Nemertea 6 Abundant 81-100%
Maja squinado 6 Frequent 41-60%
Cancer pagurus 4 Occasional 41-60%
Harmothoe impar 4 Abundant 81-100%
Asterias rubens 3 Occasional 21-40%
Heteromastus filiformis 3 Common 61-80%
Pagurus bernhardus 3 Frequent 21-40%
Anthozoa 2 Abundant 61-80%
Cirripedia 2 Common 61-80%
Turbellaria 2 Frequent 81-100%
Actinothoe sphyrodeta 2 Occasional 21-40%
Asterias rubens 2 Abundant 61-80%
Capitella capitata 2 Common 61-80%
Eteone longa 2 Abundant 61-80%
Harmothoe imbricata 2 Super abundant 61-80%
Psamathe fusca 2 Super abundant 81-100%
Necora puber 2 Occasional 21-40%
Pleuronectes platessa 2 Rare 21-40%
Spirobranchus triqueter 2 Abundant 61-80%
Nucella lapillus 2 Common 61-80%
Buccinum undatum 1 Occasional 21-40%
Crepidula fornicata 1 Occasional 21-40%
Flustra foliacea 1 Occasional 21-40%
Nereididae 1 81-100%
Paguridae 1 Occasional 21-40%
Pholoe inornata 1 Common 61-80%
Scoloplos armiger 1 Abundant 61-80%

Similar biotopes or habitat types

SS.SBR.SMus.MytSS may be an extension of the littoral biotope LS.LBR.LMus.Myt.

SS.SMx.SMxVS.AphPol may be separated from SS.SBR.SMus.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 Habitat name
2015 (15.03) SS.SBR.SMus.MytSS Mytilus edulis beds on sublittoral sediment
2004 (04.05) SS.SBR.SMus.MytSS Mytilus edulis beds on sublittoral sediment
1997 (97.06) Part of SS.IMX.EstMx.MytV Mytilus edulis beds on variable salinity infralittoral mixed sediment

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