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Marine Habitat Classification

Description of biotope or habitat type

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   Zostera marina/angustifolia beds on lower shore or infralittoral clean or muddy sand

Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Moderately exposed, Sheltered, Very sheltered, Extremely sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible)
Substratum Clean sand to muddy fine sand or mud
Zone Infralittoral
Depth Band 0-5 m, 5-10 m, Lower 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 SS.SMp.SSgr.Zmar <I>Zostera marina</I>/<I>angustifolia</I> beds on lower shore or infralittoral clean or 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'
  • 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.


Expanses of clean or muddy fine sand and sandy mud in shallow water and on the lower shore (typically to about 5 m depth) can have dense stands of Zostera marina/angustifolia [Note: the taxonomic status of Z. angustifolia is currently under consideration]. In Zmar the community composition may be dominated by these Zostera species and therefore characterised by the associated biota. Other biota present can be closely related to that of areas of sediment not containing Zostera marina, for example, Laminaria saccharina, Chorda filum and infaunal species such as Ensis spp. and Echinocardium cordatum (e.g. Bamber 1993). From the available data it would appear that a number of sub-biotopes may be found within this biotope dependant on the nature of the substratum and it should be noted that sparse beds of Zostera marina may be more readily characterised by their infaunal community. For example, coarse marine sands with seagrass have associated communities similar to MoeVen, SLan or Glap whilst muddy sands may have infaunal populations related to EcorEns, AreISa and FfabMag. Muddy examples of this biotope may show similarities to SundAasp, PhiVir, Are or AfilMysAnit. At present the data does not permit a detailed description of these sub-biotopes but it is likely that with further study the relationships between these assemblages will be clarified. Furthermore, whilst the Zostera biotope may be considered an epibiotic overlay of established sedimentary communities it is likely that the presence of Zostera will modify the underlying community to some extent. For example, beds of this biotope in the south-west of Britain may contain conspicuous and distinctive assemblages of Lusitanian fauna such as Laomedea angulata, Hippocampus spp. and Stauromedusae. In addition, it is known that seagrass beds play an important role in the trophic status of marine and estuarine waters, acting as an important conduit or sink for nutrients and consequently some examples of Zostera marina beds have markedly anoxic sediments associated with them.


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 % of core records where taxon was recorded
Anemonia viridis 3 Occasional 21-40 %
Nemertea 6 Common 41-60 %
Nematoda 5 Common 21-40 %
Exogone hebes 2 21-40 %
Platynereis dumerilii 3 Frequent 21-40 %
Scoloplos armiger 5 Abundant 41-60 %
Pygospio elegans 3 Frequent 21-40 %
Spio filicornis 2 Frequent 21-40 %
Spiophanes bombyx 1 21-40 %
Capitella capitata 2 Common 21-40 %
Mediomastus fragilis 1 Common 21-40 %
Notomastus latericeus 2 21-40 %
Arenicola marina 3 Occasional 21-40 %
Euclymene oerstedii 1 Common 1-20 %
Lanice conchilega 3 Occasional 21-40 %
Oligochaeta 1 Frequent 21-40 %
Heterochaeta costata 3 Super abundant 1-20 %
Tubificoides benedii 4 Frequent 21-40 %
Urothoe elegans 2 21-40 %
Atylus swammerdamei 2 21-40 %
Dexamine spinosa 2 Frequent 21-40 %
Dexamine thea 1 Frequent 21-40 %
Ampelisca brevicornis 3 Frequent 21-40 %
Corophium volutator 9 Abundant 21-40 %
Idotea baltica 1 21-40 %
Apseudes latreillii 1 Frequent 21-40 %
Pagurus bernhardus 2 Occasional 21-40 %
Carcinus maenas 3 Occasional 41-60 %
Chironomida 3 Abundant 1-20 %
Gibbula cineraria 1 Occasional 21-40 %
Hinia reticulata 2 Occasional 21-40 %
Thyasira flexuosa 2 1-20 %
Mysella bidentata 3 Common 21-40 %
Fabulina fabula 3 21-40 %
Abra alba 2 Common 21-40 %
Asterias rubens 2 Occasional 21-40 %
Amphipholis squamata 1 Abundant 21-40 %
Chorda filum 4 Frequent 21-40 %
Laminaria saccharina 2 Occasional 21-40 %
Ulva 2 Occasional 21-40 %
Zostera marina 52 Abundant 81-100 %

Similar biotopes or habitat types

The overlap between these two biotopes requires examination

Classification history of this biotope or habitat type

Classification version Code
96.7 IGS.Zmar
97.06 IMS.Zmar
96.7 IMS.ZmarBv

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