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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.

   Sublittoral mud in variable salinity (estuaries)

Physical habitat description

Salinity Variable (18-35 ppt)
Wave exposure Moderately exposed, Sheltered, Very sheltered, Extremely sheltered
Tidal streams Strong (3-6 kn), Moderately strong (1-3 kn), Weak (>1 kn)
Substratum Mud and sandy mud
Zone Infralittoral
Depth Band 0-5 m, 5-10 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.SMu.SMuVS Sublittoral mud in variable salinity (estuaries)

  • 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 muds, extending from the extreme lower shore into the subtidal in variable salinity (estuarine) conditions. Such habitats typically support communities characterised by oligochaetes, and polychaetes such as Aphelochaeta marioni. In lowered salinity conditions the sediments may include a proportion of coarser material, where the silt content is sufficient to yield a similar community to that found in purer muds.


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
Polychaeta 71 21-40%
Cardiidae 18 21-40%
Nephtys hombergii 18 Common 41-60%
Aphelochaeta marioni 17 Common 41-60%
Capitella capitata 9 Frequent 21-40%
Carcinus maenas 7 Rare 21-40%
Crepidula fornicata 7 21-40%
Tubificoides benedii 6 Frequent 41-60%
Streblospio shrubsolii 4 Frequent 21-40%
Tubificoides pseudogaster 3 Common 21-40%
Tubificoides swirencoides 3 Common 21-40%
Corophium volutator 2 Frequent 21-40%
Polydora ciliata 2 Common 21-40%
Pygospio elegans 2 21-40%
Macoma balthica 1 1-20%
Melinna palmata 1 Common 21-40%
Scoloplos armiger 1 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.SMu.SMuVS Sublittoral mud in variable salinity (estuaries)
2004 (04.05) SS.SMu.SMuVS Sublittoral mud in variable salinity (estuaries)
1997 (97.06) SS.IMU.EstMu Estuarine sublittoral muds

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