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Marine Habitat Classification

Description of biotope or habitat type

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   Hediste diversicolor and Scrobicularia plana in littoral gravelly mud

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Very sheltered, Extremely sheltered
Tidal streams
Substratum Gravelly mud
Depth Band Lower shore, Mid shore, 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.LMx.GvMu.HedMx.Scr <I>Hediste diversicolor</I> and <I>Scrobicularia plana</I> in littoral gravelly mud

  • 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.


Extremely sheltered gravelly mud on the mid and lower shore, containing little sand with occasional cobbles. The infaunal community includes the ragworm Hediste diversicolor and the peppery furrow shell Scrobicularia plana, as well as a range of polychaetes, oligochaetes, and molluscs. Given the low sample numbers for this biotope, more records are needed to confirm the characterising species list.


It is probable that there are broad transition areas between HedMx.Scr and the corresponding muddy sediment biotope HedMacScr. The boundaries may be very indistinct, with HedMx.Scr present in patches of gravelly mud on areas of mudflat, where the main biotope is HedMacScr.

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
Hediste diversicolor 35 Abundant 558 81-100%
Scrobicularia plana 21 Abundant 131 81-100%
Tubificoides pseudogaster 20 Abundant 1119 21-40%
Streblospio shrubsolii 7 Abundant 594 21-40%
Tubificoides benedii 5 Common 797 41-60%
Macoma balthica 3 13 21-40%
Peringia ulvae 2 Frequent 84 41-60%
Chaetozone vivipara 2 Common 169 21-40%
Pygospio elegans 2 Abundant 616 21-40%
Arenicola marina 1 Common 17 41-60%
Manayunkia aestuarina 1 Common 116 21-40%

Similar biotopes or habitat types

Occurs in lower estuarine muds and sandy muds, without a gravel fraction. The infauna is dominated by the same species, but is more diverse (though that may be an artefact of greater sample numbers in the LS.LMu.MEst.HedMacScr biotope).

Occurs lower down on the shore under more exposed conditions. The infaunal assemblage is less diverse, with fewer polychaetes and bivalves. S. plana does not occur, though Macoma balthica is abundant.

Occurs in gravelly sandy mud lower down on the shore, under more variable salinity conditions. The polychaete infauna is similar, though there may be more crustacean species, including frequent Corophium volutator, and the bivalve infauna is much reduced.

Occurs in slightly more exposed gravelly sandy mud. The principal differences in the infaunal assemblage are the greater abundance of Tharyx killariensis, the abundance of oligochaetes, and the comparative rarity of molluscs, most notably the absence of S. plana.

Occurs in more sheltered gravelly sandy mud lower on the shore. The principal differences in the infaunal assemblage are the abundance of oligochaetes and C. volutator, and the low frequency of occurrence of molluscs, most notably the absence of S. plana.

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