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Marine Habitat Classification

Description of biotope or habitat type

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   Mediomastus fragilis and cirratulids in infralittoral mixed sediment

Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt) 
Wave exposure Moderately exposed, Sheltered, Very sheltered 
Tidal streams Strong (3-6 kn), Moderately strong (1-3 kn), Weak (>1 kn) 
Substratum Mixed sediments (Gravelly muddy sand, Muddy sandy gravel)
Zone Infralittoral
Depth Band 5-10 m
Other Features

Biotope origin

Derived using data from Day grab
Faunal group Infauna

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.SMx.IMx.MedCirr  <I> Mediomastus fragilis</I> and cirratulids in infralittoral mixed sediment

  • 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.


Infralittoral shallow mixed sediment, characterised by diverse number of cirratulid polychaetes, bivalves and amphipods. This biotope has been found in Bembridge (recommended MCZ), located in the Eastern English Channel adjacent to the eastern end of the Isle of Wight. The description of this biotope is based on infauna recorded from the above location but could be found in other areas with similar environmental conditions. The most characterising species include Mediomastus fragilisand a wider cirratulid genera i.e.Chaetozone, Aphelochaeta, Caulleriella and Cirrfiromia) often with nuculid bivalves Nucula nucleus and Melinna palmata. The other polychaetes include Lumbrineris aniara, Nephtys kersivalensis, Galathowenia oculata followed by amphipods Harpinia and Ampelisca. This biotope was described using Day grab infaunal data and the characterising species listed will partly reflect the method used to collect data.


No situation data available.

Temporal variation

No temporal data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) % of core records where taxon was recorded Relative frequency %
Nucula nucleus 11 1-20% 7.4
Melinna palmata 9 1-20% 7
Chaetozone gibber 7 1-20% 3.3
Mediomastus fragilis 7 1-20% 4.7
Notomastus 6 1-20% 2.2
Euclymene oerstedi 5 1-20% 3.3
Lumbrineris aniara 4 1-20% 2.1
Ampharete finmarchica 3 1-20% 1
Chaetozone zetlandica 3 1-20% 1.8
Aphelochaeta marioni 3 1-20% 2.7
Cirriformia tentaculata 2 1-20% 0.9
Galathowenia oculata 2 1-20% 1.6
Dendrodoa grossularia 2 21-40% 23.1
Caulleriella alata 2 1-20% 0.7
Nemertea 2 1-20% 0.7
Nucula nitidosa 2 1-20% 2
Ampelisca tenuicornis 2 1-20% 2.5
Nephtys kersivalensis 2 1-20% 0.4
Harpinia pectinata 1 1-20% 0.6
Diastylis rugosa 1 1-20% 0.4
Pisidia longicornis 1 1-20% 3.8
Sthenelais boa 1 1-20% 0.3
Spirobranchus lamarcki 1 1-20% 3.2
Scoloplos 1 1-20% 0.3
Maera grossimana 1 1-20% 0.6
Abra alba 1 1-20% 0.3
Amphipholis squamata 1 1-20% 0.7
Escharella immersa 1 1-20% 0.1

Similar biotopes or habitat types

Not applicable or unknown.

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