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Marine Habitat Classification

Description of biotope or habitat type

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   Polydora ciliata and Corophium volutator in variable salinity infralittoral firm mud or clay

Physical habitat description

Salinity Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams Weak (>1 kn)
Substratum Hard clay, relict peat, mud with fine sand fraction
Zone Infralittoral
Depth Band 0-5 m, 5-10 m
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 SS.SMu.SMuVS.PolCvol <I>Polydora ciliata</I> and <I>Corophium volutator</I> in variable salinity infralittoral firm mud or clay

  • 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.


Variable salinity clay and firm mud characterised by a turf of the polychaete Polydora ciliata along with the amphipod Corophium volutator. Other important taxa include the polychaetes Pygospio elegans, Hediste diversicolor, Streblospio shrubsolii and the oligochaete Tubificoides benedii. P. ciliata also occurs in high densities elsewhere (see MCR.Pol) and may be a specific feature of the Humber Estuary in these conditions. This biotope occurs only in very firm mud and clay and possibly submerged relict saltmarsh with a high detrital content. It is characterised, and can be separated from other biotopes, by a combination of the sediment characteristics and the very high density of Polydora ciliata. In some areas, such as the Humber estuary, cyclical behaviour with regard its characteristic taxa has been reported with either P. ciliata or C. volutator increasing in dominance at the expense of the other (Gameson 1982). It is possible that changes in water quality or the sediment regime may be responsible for this.


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 Typical abundance - (count per m2) % of core records where taxon was recorded
Eteone longa 2 Common 32 41-60 %
Hediste diversicolor 5 Common 84 61-80 %
Polydora ciliata 43 Abundant 6407 81-100 %
Pygospio elegans 9 Frequent 152 61-80 %
Streblospio shrubsolii 6 Common 642 41-60 %
Tharyx 2 Common 877 21-40 %
Tubificoides benedii 4 Frequent 616 61-80 %
Tubificoides pseudogaster 2 Abundant 2850 21-40 %
Gammarus salinus 1 Common 6 21-40 %
Corophium volutator 21 Common 556 61-80 %
Hydrobia ulvae 1 Common 332 21-40 %

Similar biotopes or habitat types

These two biotopes are similar in characteristics but can be distinguished on the relative abundances of the characterising species Polydora ciliata, Corophium volutator and Aphelochaeta marioni.

Classification history of this biotope or habitat type

Classification version Code
97.06 IMU.PolVS

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