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Marine Habitat Classification


Description of biotope or habitat type

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   Zostera noltii beds in littoral muddy sand


Habitat (physical) description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams
Substratum Muddy sand
Zone
Depth Band Mid 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.LMp.LSgr.Znol <I>Zostera noltii</I> beds 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.

Description

Mid and upper shore wave-sheltered muddy fine sand or sandy mud with narrow-leafed eel grass Zostera noltii at an abundance of frequent or above. It should be noted that the presence of Z. noltii as scattered fronds does not change what is otherwise a muddy sand biotope. Exactly what determines the distribution of Z. noltii is not entirely clear. It is often found in small lagoons and pools, remaining permanently submerged, and on sediment shores where the muddiness of the sediment retains water and stops the roots from drying out. An anoxic layer is usually present below 5 cm sediment depth. The infaunal community is characterised by the polychaetes Scoloplos armiger, Pygospio elegans and Arenicola marina, oligochaetes, the spire shell Hydrobia ulvae, and the bivalves Cerastoderma edule and Macoma balthica. The green algae Enteromorpha spp. may be present on the sediment surface. The characterising species lists below give an indication both of the epibiota and of the sediment infauna that may be present in intertidal seagrass beds. The biotope is described in more detail in the National Vegetation Classification (see the chapter on saltmarsh communities in Rodwell, 2000) (*** this will be a hyperlink to an electronic copy of the mentioned chapter).

Situation

Znol is most frequently found on lower estuary and sheltered coastal muddy sands, together with biotopes such as CerPo.

Temporal variation

There may be seasonal variation in the area covered by intertidal seagrass beds, as plants die back during cold temperatures in winter. Intertidal seagrass beds may also be subject to heavy grazing by geese, which can reduce the extent of the plant cover significantly. The rhizomes of the plants will remain in place within the sediment in both situations.

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Scoloplos armiger 23 Super abundant 61-80 %
Pygospio elegans 5 Common 41-60 %
Arenicola marina 11 Abundant 81-100 %
Arenicola marina 7 Abundant 21-40 %
Oligochaeta 1 Common 21-40 %
Hydrobia ulvae 2 Common 21-40 %
Cerastoderma edule 4 Abundant 41-60 %
Macoma balthica 47 Common 81-100 %
Enteromorpha 2 21-40 %
Zostera 82 61-80 %
Zostera noltii 2 Common 21-40 %

Similar biotopes

LS.LSa.MuSa.CerPo
Occurs under more estuarine but otherwise similar conditions. The infaunal communities are similar, but Zostera spp. are absent.

Biotope history

Classification Habitat code
96.7 LMS.PCer.Znol
97.06 LMS.Zos.Znol
6.95 LMUD.HS.Z

Photos

LS.LMP.LSGR.Znol Zostera noltii beds in littoral muddy sand, Rough Island Causeway and Flats, Inner Solway. Mark Davies © JNCC
LS.LMP.LSGR.Znol Zostera noltii beds in littoral muddy sand, Rough Island Causeway and Flats, Inner Solway. Mark Davies © JNCC
LS.LMP.LSGR.Znol Zostera noltii beds in littoral muddy sand, Rough Island Causeway and Flats, Inner Solway. Mark Davies © JNCC
LS.LMP.LSGR.Znol Zostera noltii beds in littoral muddy sand, Rough Island Causeway and Flats, Inner Solway. Mark Davies © JNCC
LS.LMP.LSGR.Znol Zostera noltii beds in littoral muddy sand, Rough Island Causeway and Flats, Inner Solway. Mark Davies © JNCC
LS.LMP.LSGR.Znol Zostera noltii beds in littoral muddy sand, Rough Island Causeway and Flats, Inner Solway. Mark Davies © JNCC

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