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.

   Hediste diversicolor, Macoma balthica and Eteone longa in littoral muddy sand

Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure
Tidal streams
Substratum Muddy sand
Depth Band 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.LSa.MuSa.HedMacEte <I>Hediste diversicolor</I>, <I>Macoma balthica</I> and <I>Eteone longa</I> in littoral muddy 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'

Point data based on records in the UK Marine Recorder Snapshot.


Fine to very fine muddy sand on the mid shore at the lower extreme of estuaries, and in moderately exposed and sheltered bays and marine inlets, sometimes subject to variable salinity. The infauna is characterised by the polychaetes Eteone longa, Hediste diversicolor (ragworm) and Pygospio elegans, oligochaetes (mostly Tubificoides benedii and T. pseudogaster), the crustaceans Corophium volutator and Crangon crangon, the spire shell Peringia ulvae and the baltic tellin Macoma balthica. The cockle Cerastoderma edule may be abundant, and the sand gaper Mya arenaria may be superabundant, though these species are not always present, or may be missed in core samples due to their large size. The polychaetes Arenicola marina, Polydora cornuta and Capitella capitata, the shrimp Crangon crangon, and the Mussel Mytilus edulis are sometimes present.


HedMacEte can occur on the mid shore of sheltered, lower estuaries, with the MEST communities in muddier sediments on the lower shore. Under moderately exposed conditions in lower estuaries and towards open coasts, it may occur alongside other muddy sand biotopes such as CerPo or BatCare.

Temporal variation

Enteromorpha spp. or Ulva lactuca may form mats on the surface of the sediment during the summer months, particularly in areas of freshwater influence and/or where there is nutrient enrichment.

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
Pygospio elegans 17 Common 1043 81-100%
Macoma balthica 16 Common 1722 81-100%
Hediste diversicolor 14 Abundant 665 81-100%
Oligochaeta 13 Abundant 5060 81-100%
Eteone longa 9 Abundant 275 61-80%
Peringia ulvae 6 Abundant 2514 41-60%
Corophium volutator 6 Abundant 2776 61-80%
Nematoda 5 Common 536 61-80%
Cerastoderma edule 4 Abundant 741 41-60%
Mya arenaria 3 Super abundant 346 41-60%
Crangon crangon 1 Common 25 21-40%

Similar biotopes or habitat types

These biotopes occur in slightly more exposed, marine sediments which lack a silt/clay fraction. The principal infaunal difference is the absence of C. edule and M. balthica.

Occurs in more sheltered, less saline, mid-shore or lower shore sandy mud and mud. E. longa and P. elegans are less consistently present, but Tubificoides spp. are abundant.

Occurs in less saline, more sheltered muddy conditions on the lower shore, further towards the head of estuaries. There is a greater diversity of polychaetes, M. balthica is not always present, but Scrobicularia plana occurs in high densities.

Occurs lower down on the shore, in muddier sediments. H. diversicolor occurs only occasionally, but Nephtys hombergii tends to be abundant. Tubificoides spp. are common.

Occurs in similar environmental conditions, though on more sheltered coasts and only rarely where there is freshwater influence. H. diversicolor is absent, and fewer mollusc species are present. M. arenaria and H. ulvae do not occur.

Occurs in less saline, more sheltered muddy conditions on the lower shore, further towards the head of estuaries. P. elegans occurs less frequently, Streblospio shrubsolii is abundant. The only molluscs that occur are occasionally common Peringia ulvae and S. plana.

Occurs in more sheltered, less saline, mid-and lower-shore sandy mud. The polychaete fauna is a lot poorer, and bivalves are virtually absent.

Classification history of this biotope or habitat type

Classification version Code
2015 (15.03) LS.LSa.MuSa.HedMacEte
1997 (97.06) LMS.MS.MacAre (part)
1997 (97.06) LMU.SMu.HedMac.Are (part)
1997 (97.06) LMU.SMu.HedMac.Mare (part)
1996 (6.95) LMS.AreBv (part)

Back to top