Zostera Biotope Classification

The MNCR Biotope classification scheme

‘Bio Mar’ Biotope classification scheme

The MNCR Biotope classification scheme

The Marine Nature Conservation Review (MNCR) biotope classification provides a hierarchical framework for differentiating and classifying the shallow-water benthic habitats and biological communities of the British Isles (Connor et al., 1997). The basic unit of classification is the Biotope, a recognizable Community of conspicuous species occurring in a Habitat, defined according to parameters of the physical environment such as substratum type or degree of wave exposure. Groups of biotopes with similar overall character, suitable for local mapping where biotopes consistently occur together and are relatively restricted in their extent, are termed Biotope complexes. The current version of the MNCR biotope classification (Connor et al., 1997) lists two main biotopes characterized by Zostera beds. The defining characteristics of these are summarized in the table below:

MNCR biotopes characterized by Zostera spp.

LMS.Znol : Zostera noltii beds in upper to mid shore muddy sand
Salinity

Wave exposure

Substratum

 

Zone

Height band

Characterizing species

 

 

 

 

 

Frequency of occurrence

 Full - variable (8-30 %0)

Sheltered - very sheltered - extremely sheltered

Muddy fine sand - sandy mud

A black layer in sediments usually present below 5 cm depth

Eulittoral

Upper shore - mid shore

Infaunal community: bristle worm (Pygospio elegans) & lugworm (Arenicola marina), sludge worms (Tubificoides), amphipods Corophium volutator and bivalves - cockles (Cerastoderma edule), Baltic tellin (Macoma baltica) and peppery furrow shell (Scrobicularia plana)

Epifaunal community: mud snail (Hydrobia ulvae), common periwinkle (L. littorea), shore crab (Carcinus maenus) and ribbon weed (Enteromorpha)

Scarce
IMS.Zmar:

Zostera marina / Z. angustifolia beds in lower shore or infralittoral clean or muddy sand
Salinity

Wave exposure

Tidal streams

Substratum

Zone

Height band

Depth band

Characterizing species

 

 

 

 

 

 

 

 

 

Frequency of occurrence

Full

Sheltered - very sheltered

Very weak

Clean sand - muddy fine sand - mud

Infralittoral

Lower shore

0 - 5 m

Infaunal community: burrowing urchin (Echinocardium cordatum), razor shells (Ensis sp.) and other bivalves, lugworm (Arenicola marina), sandmason worm ( Lanice conchilega).

Epifaunal community: snakelocks anemone (Anemonia viridis), hermit crab (Pagarus bernhardus), shore crab (C. maenus), grey topshell (Gibbula cineraria), netted dogwhelk (Hinia reticulata) as well the algae, Laminaria saccharina, Chorda filum and Ulva.

In SW Britain, the community composition may be dominated by Lusitanian species such as the hydroid Laomeda angulata, seahorses Hippocampus sp. and stalked jellyfish (Stauromedusae)

Uncommon

 

‘Bio Mar’ Biotope classification scheme:

The ‘BioMar’ classification system is closely related to the MNCR scheme, and is intended for basic mapping of intertidal and subtidal habitats and associated communities. It is based around a number of major physical categories of characterizing organisms, termed ‘Life Forms’, which can be further subdivided according to details of their composition. The treatment of Zostera biotopes within this scheme is outlined in the table below:

BioMar’ biotopes within the overall Life Form SGB - Sea Grass Beds. (Bunker & Foster-Smith, 1996.)

Life Form SGB - Sea Grass Beds
SGB.Z

Seagrass beds: Zostera sp.

Community description:

    • Zostera sp. (Z. angustifolia or Z. noltii) may form sparse to moderately dense stands.
    • Can colonize a wide variety of sediment shores so the underlying faunal communities will vary but usually contains Hediste diversicolor.
  • Habitat description:
    • Sandy mud to mud
    • Whole shore, mainly upper to middle
    • Sheltered to very sheltered

Biotopes of enclosed tidal waterways and estuaries
SGB.ZOS

Seagrass beds: Zostera marina

Community description:

    • Zostera marina may form dense stands
    • Can colonize a wide variety of sediment substrates so the underlying faunal communities will vary but will usually contain polychaetes such as Nephtys hombergii and Scoloplos armiger and bivalves such as Ensis siliqua and Cerastoderma edule.

Habitat description:

    • Fine muddy sand
    • Lower shore and shallow sublittoral
    • Sheltered to very sheltered

Biotopes of enclosed tidal waterways and estuaries

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