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 |
Biotope origin
| Derived using data from | Various |
| Faunal group | Epifauna |
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
Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.
Description
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 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 SS.SMu.CFiMu.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).
Situation
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 |
|---|---|---|---|
| Amphiura chiajei | 56 | Abundant | 81-100% |
| Amphiura filiformis | 27 | Abundant | 81-100% |
| Ophiura ophiura | 3 | Occasional | 41-60% |
| Virgularia mirabilis | 3 | Occasional | 41-60% |
| Brissopsis lyrifera | 2 | 21-40% | |
| Pectinaria belgica | 2 | 41-60% | |
| Nephtys hystricis | 1 | 21-40% |
Similar biotopes or habitat types
SS.SMu.CFiMu.SpnMeg
SS.SMu.CFiMu.SpnMeg is closely allied to SS.SMu.CFiMu.BlyrAchi 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.
SS.SMu.CSaMu.AfilKurAnit
This community is similar to SS.SMu.CSaMu.AfilKurAnit but tends to occur in deeper and siltier muds. Transitional communities between the two may contain large numbers of Turritellinella tricarinata.Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SMu.CFiMu.BlyrAchi | Brissopsis lyrifera and Amphiura chiajei in circalittoral mud |
| 2004 (04.05) | SS.SMu.CFiMu.BlyrAchi | Brissopsis lyrifera and Amphiura chiajei in circalittoral mud |
| 1997 (97.06) | SS.CMU.BriAchi | Brissopsis lyrifera and Amphiura chiajei in circalittoral mud |