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Marine Habitat Classification

Description of biotope or habitat type

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   Brissopsis lyrifera and Amphiura chiajei in circalittoral mud

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed, Sheltered, Very sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Silty mud
Zone Circalittoral
Depth Band 20-30 m, 30-50 m, 50-100 m
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 SS.SMu.CFiMu.BlyrAchi <I>Brissopsis lyrifera</I> and <I>Amphiura chiajei</I> in circalittoral 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'
  • 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.


Mud in deep offshore, or shallower stable nearshore, waters can be characterised by the urchin Brissopsis lyrifera and the brittle star Amphiura chiajei. Where intense benthic dredge fishing activity occurs, populations of the indicator species, Brissopsis lyrifera may be depressed, although broken tests may still remain (E.I.S. Rees pers. comm. 1997; M. Costello pers. comm. 1997). Low numbers of the seapen Virgularia mirabilis may be found in many examples of this biotope. In addition, in certain areas of the UK such as the northern Irish Sea, this community may also contain Nephrops norvegicus and can consequently be the focus for fishing activity (Mackie, Oliver & Rees 1995). Infaunal species in this community are similar to those found in SpnMeg and include the polychaetes Nephtys hystricis, Pectinaria belgica, Glycera spp. and Lagis koreni and the bivalves Myrtea spinifera and Nucula sulcata. This community is the 'Boreal Offshore Mud Association' and 'Brissopsis - Chiajei' communities described by other workers (Petersen 1918; Jones 1950).


No situation data available.

Temporal variation

No temporal data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Virgularia mirabilis 3 Occasional 41-60 %
Nephtys hystricis 1 21-40 %
Pectinaria belgica 2 41-60 %
Amphiura chiajei 56 Abundant 81-100 %
Amphiura filiformis 27 Abundant 81-100 %
Ophiura ophiura 3 Occasional 41-60 %
Brissopsis lyrifera 2 21-40 %

Similar biotopes or habitat types

SpnMeg is closely allied to BriAchi and may show strong similarities in infaunal species composition. However, epifaunally they differ in the abundance of characterising species such as Pennatula phosphorea and Amphiura spp.

This community is similar to AfilMysAnit but tends to occur in deeper and siltier muds. Transitional communities between the two may contain large numbers of Turritella communis.

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