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Marine Habitat Classification

Description of biotope or habitat type

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   Circalittoral muddy sand

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible)
Substratum Fine to very fine sand with a fine silt fraction
Zone Circalittoral
Depth Band 10-20 m, 20-30 m, 30-50 m
Other Features

Biotope origin

Derived using data from Various
Faunal group 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.SSa.CMuSa Circalittoral muddy sand

  • 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.


Circalittoral non-cohesive muddy sands with the silt content of the substratum typically ranging from 5% to 20%. This habitat is generally found in water depths of over 15-20m and supports animal-dominated communities characterised by a wide variety of polychaetes, bivalves such as Abra alba and Nucula nitidosa, and echinoderms such as Amphiura spp and Ophiura spp., and Astropecten irregularis. These circalittoral habitats tend to be more stable than their infralittoral counterparts and as such support a richer infaunal community.


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
Acrocnida brachiata 18 Common 61-80%
Asterias rubens 14 Occasional 61-80%
Abra alba 12 Abundant 81-100%
Nucula nitidosa 11 Frequent 81-100%
Pagurus bernhardus 8 Occasional 61-80%
Fabulina fabula 7 Common 61-80%
Astropecten irregularis 6 Occasional 41-60%
Chaetozone setosa 6 Common 61-80%
Ophiura ophiura 6 Occasional 41-60%
Spiophanes bombyx 6 Frequent 61-80%
Echinocardium cordatum 5 Rare 41-60%
Metridium senile 5 Rare 21-40%
Nephtys 5 Common 61-80%
Lanice conchilega 4 Occasional 41-60%
Scoloplos armiger 3 61-80%
Pomatoschistus minutus 3 Occasional 21-40%
Abra prismatica 2 Frequent 41-60%
Corystes cassivelaunus 2 Occasional 21-40%
Goniada maculata 2 41-60%
Lanice conchilega 2 41-60%
Liocarcinus depurator 2 Rare 21-40%
Macropodia rostrata 2 Rare 21-40%
Nemertea 2 41-60%
Nephtys hombergii 2 Common 41-60%
Ophiura albida 2 Occasional 21-40%
Owenia fusiformis 2 41-60%
Philine aperta 2 Occasional 21-40%
Scalibregma inflatum 2 41-60%
Solenidae 2 Super abundant 21-40%
Bathyporeia tenuipes 1 41-60%
Cerianthus lloydii 1 Frequent 41-60%
Chamelea gallina 1 41-60%
Corystes cassivelaunus 1 41-60%
Gari fervensis 1 41-60%
Oestergrenia digitata 1 Occasional 21-40%
Ophiura albida 1 Abundant 41-60%
Prionospio fallax 1 41-60%
Cylista undata 1 Occasional 21-40%
Sthenelais limicola 1 41-60%
Seraphsidae 1 Occasional 21-40%

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code Habitat name
2015 (15.03) SS.SSa.CMuSa Circalittoral muddy sand
2004 (04.05) SS.SSa.CMuSa Circalittoral muddy sand
1997 (97.06) Part of SS.CMS Circalittoral muds

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