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.

   Nephtys cirrosa and Macoma balthica in variable salinity infralittoral mobile sand

Physical habitat description

Salinity Variable (18-35 ppt)
Wave exposure Moderately exposed, Sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn)
Substratum Medium to very fine sand
Zone Infralittoral
Depth Band 0-5 m, 5-10 m, 10-20 m
Other Features Surface veneer of mud may be present at slack water

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.SSaVS.NcirMac <I>Nephtys cirrosa</I> and <I>Macoma balthica</I> in variable salinity infralittoral mobile 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.


Mobile sand in variable salinity conditions where tidal currents create an unstable shifting habitat. Characteristic species include the polychaetes Nephtys cirrosa and Scoloplos armiger along with amphipods of the genus Bathyporeia and Haustorius arenarius. The bivalve Macoma balthica may occur in more stable examples of this biotope, although not in the abundances found in the NhomMac. The biotope contains relatively few species, each typically in low to moderate abundance. It is found in tidal channels with moderate tidal streams. Care should be taken in identification of this biotope due to the presence juveniles and species washed in during slack water.


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
Nephtys cirrosa 59 Common 22 61-80 %
Scoloplos armiger 6 Abundant 5 21-40 %
Capitella capitata 2 4 21-40 %
Bathyporeia pelagica 2 Frequent 9 1-20 %
Bathyporeia pilosa 13 Frequent 90 21-40 %
Haustorius arenarius 4 Frequent 14 21-40 %
Macoma balthica 5 Frequent 7 21-40 %

Similar biotopes or habitat types

As wave exposure and /or current strength decreases and the finer sand and silt fractions begin to sediment out of the water column, the sediment habitat is less mobile and MoSaVS grades into NcirMac

The current biotope is a reduced salinity version of NcirBat, distinguished from this by the absence of species not tolerant of reduced salinities, in particular the polychaete Chaetozone setosa.

Back to top