Skip to Content

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 and Fabricia stellaris in littoral mixed sediment

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams
Substratum Mixed sediment, shell debris
Depth Band
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 LS.LSa.St.MytFab <I>Mytilus edulis</I> and <I>Fabricia stellaris</I> in littoral mixed 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'

Point data based on records in the UK Marine Recorder Snapshot.


Pebbles, gravel, sand and shell debris with mud in sheltered Firths with a strandline of fucoid algae. The fauna is characterised by juvenile mussels Mytilus edulis, often in very high numbers. The nemertean worm Lineus spp. may be abundant and oligochaetes are common. Polychaetes such as Pygospio elegans, Scoloplos armiger and Fabricia stellaris may be present in high densities. Fabricia stellaris is typically found amongst algal holdfasts and between cobbles on rocky shores. The bivalves Macoma balthica and Cerastoderma edule, typical of muddy sediments, characterise the community. The validity of this biotope is uncertain, as the only available data, from the Dornoch Firth and the Moray Firth, are poor. Its position within the classification, as a strandline community, is also very uncertain, but there is not enough information available for a better description or classification at this stage.


Occurs on sheltered shores of the Dornoch Firth and Moray Firth.

Temporal variation

Not known.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale Typical abundance - (count per m2) % of core records where taxon was recorded
Macoma balthica 37 Abundant 37 81-100%
Pygospio elegans 13 Abundant 100 81-100%
Oligochaeta 12 Common 83 81-100%
Peringia ulvae 11 Abundant 67 61-80%
Mytilus edulis 11 Abundant 100 81-100%
Fabricia stellaris 6 Common 89 81-100%
Scoloplos armiger 6 Super abundant 72 61-80%
Cerastoderma edule 2 Abundant 50 41-60%
Lineus 2 Abundant 75 61-80%

Similar biotopes or habitat types

Occurs on mixed substrates, often under variable salinity, lower on the shore. Adult M. edulis form beds on the surface of the sediment. LR.LLR.Few polychaetes are recorded for LS.LBR.LS.LMus.Myt, though that may result from a lack of infaunal sampling. A range of rocky shore species occur attached to scattered cobbles and boulders, including LR.HLR.MusB.Semibalanus balanoides, Austrominius modestus, Littorina spp., and Fucus vesiculosus.

Classification history of this biotope or habitat type

Classification version Code
2015 (15.03) LS.LSa.St.MytFab

Back to top