Zostera noltii beds on Atlantic littoral mud
|EUNIS habitat type||code MA6231|
|Relation to||Resolution 4 habitat type (used for designation of Emerald sites)|
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 Limecola balthica (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 British National Vegetation Classification (see the chapter on saltmarsh communities in Rodwell, 2000).
Situation: Z. noltii is most frequently found on lower estuary and sheltered coastal muddy sands, together with biotopes such as unit MA5-252.
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.
Source: EUNIS habitat classification
Relation to other habitat types mentioned in legal instruments
Relation to vegetation types (syntaxa)Not available
Species mentioned in habitat description
|Species scientific name||English common name||Species group|
|Zostera noltii||Flowering Plants|
|Classification||Code||Habitat type name||Relationship type|
|EUNIS Habitat Classification 2007 (revised descriptions 2012)||A2.6111||Zostera noltii beds in littoral muddy sand||overlap|
|Classification||Code||Habitat type name||Relationship type||Comment|
|EUNIS Habitat Classification 200410||A2.6111||Zostera noltii beds in littoral muddy sand||same|
|EUNIS Habitat Classification 200308||A2.7111||Zostera noltii beds in littoral muddy sand||same|
|EUNIS Habitat Classification 200202||A2.7111||Zostera noltii beds in upper to mid shore muddy sand||same|
|EUNIS Habitat Classification 199910||A2.7111||Zostera noltii beds in upper to mid shore muddy sand||same|
|MNCR BioMar 97.06 (Britain & Ireland)||LMS.Zos.Znol||Zostera noltii beds in upper to mid shore muddy sand||same|