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Marine Habitat Classification


Description of biotope or habitat type

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   Mytilus edulis beds on littoral mud


Habitat (physical) description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Moderately exposed, Sheltered
Tidal streams
Substratum Sandy mud and mud
Zone
Depth Band Lower shore, 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.LBR.LMus.Myt.Mu <I>Mytilus edulis</I> beds on littoral mud

  • 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

Dense mussel beds found in sheltered conditions on mud. There is a build up of pseudofaeces that results in a bed that is very soft to walk on, and sediment which is anoxic to the surface. Pools are often present in the mussel bed but they tend to contain few species. The sediment infauna is very poor as a result of anoxic conditions. The mussel valves are usually clean, without epifaunal growth. Where this biotope occurs naturally, all age classes are found within the mussel bed. This biotope also includes commercially laid mussel beds on soft sediments, which tend to be of uniform age structure. The species diversity of this sub-biotope is a lot lower than that of the other Myt sub-biotopes.

Situation

Occurs on sheltered mudflats, or areas that were previously rocky or cobble fields, but where pseudofaeces have accumulated, leading to the presence of a thick layer of mud.

Temporal variation

Mussels may settle on areas of cobble or mixed sediment (Myt.Mx), and lead to the build-up of a thick layer of pseudofaeces, changing the biotope to Myt.Mu over time. The layer of mud can prevent the attachment of mussels to the underlying stable substratum, thus making the mussel bed liable to be washed away during storms. This is known to occur in areas of Morecambe Bay.

Characterising Species

Characterising species data not applicable.

Similar biotopes

LS.LBR.LMus.Myt.Mx
Occurs on mixed substrata, often in more exposed conditions near predominantly rocky areas. Species diversity is higher, with cobbles and boulders supporting epifaunal species typical of rocky shores, and limited infauna present in sediment patches.

LS.LBR.LMus.Myt.Sa
Occurs on sand and muddy sand. As well as mussel beds, there is a diverse infaunal community including a range of bivalves such as Cerastoderma edule and Macoma balthica, and a range of polychaetes.

Biotope history

Classification Habitat code
6.95 LMXD.MYT (part)
97.06 SLR.MX.MytX (part)

Photos

LS.LMX.LMUS.Myt.Mu Mytilus edulis beds on littoral mud, Burry Inlet. Aethne Cooke © NRW
LS.LMX.LMUS.Myt.Mu Mytilus edulis beds on littoral mud, Burry Inlet. Aethne Cooke © NRW
LS.LMX.LMUS.Myt.Mu Mytilus edulis beds on littoral mud, Burry Inlet. Aethne Cooke © NRW
LS.LMX.LMUS.Myt.Mu Mytilus edulis beds on littoral mud, Burry Inlet. Aethne Cooke © NRW

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