Description of biotope or habitat type
Brissopsis lyrifera and Amphiura chiajei in circalittoral mud
Habitat (physical) description
|Salinity||Full (30-35 ppt)|
|Wave exposure||Moderately exposed, Sheltered, Very sheltered|
|Tidal streams||Weak (>1 kn), Very weak (negligible)|
|Depth Band||20-30 m, 30-50 m, 50-100 m|
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.
- 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
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.
No temporal data available.
|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 %|