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Marine Habitat Classification

Description of biotope or habitat type

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   Polychaete/bivalve-dominated muddy sand shores

Physical habitat description

Salinity Full (30-35 ppt), Reduced (18-30ppt), Variable (18-35 ppt)
Wave exposure Moderately exposed, Sheltered, Very sheltered, Extremely sheltered
Tidal streams
Substratum Fine sand or muddy sand
Depth Band Lower shore, Mid shore, Strandline, Upper shore
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.MuSa Polychaete/bivalve-dominated muddy sand shores

  • 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.


Muddy sand or fine sand, often occurring as extensive intertidal flats on open coasts and in marine inlets. The sediment generally remains water-saturated during low water. The habitat may be subject to variable salinity conditions in marine inlets. An anoxic layer may be present below 5 cm of the sediment surface, sometimes seen in the worm casts on the surface. The infauna consists of a diverse range of amphipods, polychaetes, bivalves and gastropods.


Muddy sand communities are found predominantly on the mid and lower shore, though they may span the entire intertidal. Fine sand or mobile sand communities may be present on the upper shore with muddy sand communities present lower down. In sheltered mid estuarine conditions, muddy sand communities may be present on the upper part of the shore with mid estuarine muddy shore communities (MEST) lower down.

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 22 Common 786 81-100%
Pygospio elegans 15 Common 670 61-80%
Peringia ulvae 11 Abundant 2829 41-60%
Cerastoderma edule 10 Abundant 504 61-80%
Oligochaeta 6 Abundant 1703 41-60%
Eteone longa 6 Abundant 114 41-60%
Hediste diversicolor 5 Common 229 41-60%
Bathyporeia pilosa 3 Common 446 21-40%
Corophium arenarium 3 Common 437 21-40%
Corophium volutator 3 Common 1074 21-40%
Scoloplos armiger 3 Abundant 66 21-40%
Nematoda 2 Common 213 21-40%
Crangon crangon 2 Common 25 21-40%
Capitella capitata 1 Frequent 78 21-40%

Similar biotopes or habitat types

Not applicable or unknown.

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