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Marine Habitat Classification

Description of biotope or habitat type

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   Hediste diversicolor in littoral gravelly muddy sand and gravelly sandy mud

Physical habitat description

Salinity Reduced (18-30ppt), Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams
Substratum Gravelly sandy mud
Depth Band Lower shore, Mid shore, Strandline, 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 <I>Hediste diversicolor</I> in littoral gravelly muddy sand and gravelly sandy 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.


Sheltered gravelly sandy mud, subject to reduced salinity, mainly on the mid and lower shore. The infaunal community is dominated by abundant ragworms Hediste diversicolor. Other species of the infauna vary for the sub-biotopes described. They include polychaetes such as Pygospio elegans, Streblospio shrubsolii, and Manayunkia aestuarina, oligochaetes such as Baltidrilus costatus and Tubificoides spp., the mud shrimp Corophium volutator, the spire shell Peringia ulvae, the baltic tellin Macoma balthica and the peppery furrow shell Scrobicularia plana. Sub-biotopes described in HedMx have equivalent communities in soft muddy sediments, but the sediment here is much firmer due to the gravel component. There are relatively few records in each sub-type, leading to uncertainty over the precise nature of the habitat, particularly regarding sediment type and salinity regime.


It is probable that there are broad transition areas between the sub-biotopes of HedMx, and the corresponding muddy sediment biotopes. The boundaries may be very indistinct, with the HedMx groups present in patches of gravelly mud on areas of mudflat where the main biotopes are their corresponding mud or sandy mud biotopes. Given the small number of records for each of the sub-biotopes, their spatial distribution is still uncertain.

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 62 Abundant 1406 81-100%
Tubificoides pseudogaster 6 Abundant 1796 41-60%
Corophium volutator 5 Common 2704 41-60%
Streblospio shrubsolii 4 Common 1099 41-60%
Baltidrilus costatus 3 Common 4198 21-40%
Tubificoides benedii 3 Common 1759 41-60%
Peringia ulvae 2 Common 366 21-40%
Macoma balthica 2 Common 72 21-40%
Pygospio elegans 2 Common 207 21-40%
Scrobicularia plana 2 Abundant 62 41-60%
Manayunkia aestuarina 1 Common 1420 21-40%

Similar biotopes or habitat types

Occurs in lower estuarine muds and sandy muds, without a gravel fraction. The infauna is more diverse, particularly containing a greater number of bivalves (though that may be an artefact of greater number of samples in the LS.LMu.MEst.HedMac biotope).

Occurs in estuarine muds, without a gravel fraction. The infauna is dominated by similar species.

Occurs in estuarine muds, without a gravel fraction. The infauna consists virtually entirely of H. diversicolor and C. volutator.

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