Description of biotope or habitat type
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Thyasira spp. and Ennucula tenuis in circalittoral sandy mud
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed, Sheltered |
| Tidal streams | Very weak (negligible) |
| Substratum | Mud occasionally with scattered shells or gravel |
| Zone | Circalittoral |
| Depth Band | 20-30 m, 30-50 m, 50-100 m |
| Other Features |
Biotope origin
| Derived using data from | Various |
| 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.
- 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
Circalittoral cohesive sandy muds with small quantities of gravel, off sheltered or moderately exposed coasts may support populations characterised by Thyasira spp., in particular Thyasira flexuosa. Other characteristic taxa may include Ennucula tenuis, Goniada maculate and in some areas Rhodine gracilior. Kurtiella bidentata, Abra alba, Harpinia antennaria and Amphiura filiformis may be abundant in some examples of this biotope. Whilst moderately diverse, animal abundances are often low and it is possible that the biotope is the result of sedimentary disturbance e.g. from trawling and is possibly an impoverished version of SS.SMu.CSaMu.AfilEten. Collectively the biotopes SS.SMu.CSaMu.ThyEten, SS.SMu.CSaMu.AfilKurAnit, SS.SMu.CSaMu.AfilEten, SS.SMu.OMu.PjefThyAfil, and SS.SSa.OSa.OfusAfil, may form the Amphiura dominated components of the 'off-shore muddy sand association' described by other workers (Jones 1951; Thorson 1957; Mackie 1990) and the infralittoral etage described by Glemarec (1973).
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 |
|---|---|---|---|
| Thyasira flexuosa | 50 | Occasional | 81-100% |
| Abra alba | 25 | 81-100% | |
| Mya arenaria | 25 | 81-100% | |
| Thyasira flexuosa | 12 | Frequent | 61-80% |
| Nemertea | 7 | 61-80% | |
| Goniada maculata | 5 | 61-80% | |
| Ennucula tenuis | 4 | Frequent | 41-60% |
| Rhodine gracilior | 4 | Common | 41-60% |
| Abra alba | 3 | 41-60% | |
| Amphiura filiformis | 3 | Abundant | 41-60% |
| Galathowenia oculata | 3 | 21-40% | |
| Harpinia antennaria | 3 | Frequent | 41-60% |
| Abyssoninoe hibernica | 3 | 21-40% | |
| Kurtiella bidentata | 3 | Frequent | 41-60% |
| Terebellides stroemii | 3 | 21-40% | |
| Chaetozone setosa | 2 | 41-60% | |
| Cylichna cylindracea | 2 | 41-60% | |
| Diplocirrus glaucus | 2 | 41-60% | |
| Glycera unicornis | 2 | 21-40% | |
| Lucinoma borealis | 2 | 41-60% | |
| Nephtys | 2 | 41-60% | |
| Owenia fusiformis | 2 | Common | 21-40% |
| Paraonidae | 2 | 21-40% | |
| Anobothrus gracilis | 1 | 21-40% | |
| Phaxas pellucidus | 1 | 21-40% | |
| Pholoe inornata | 1 | 21-40% | |
| Scalibregma inflatum | 1 | Common | 21-40% |
| Spiophanes bombyx | 1 | 21-40% | |
| Spiophanes kroyeri | 1 | 21-40% | |
| Virgularia mirabilis | 1 | 21-40% | |
| Thyasira | 1 | Common | 1-20% |
Similar biotopes or habitat types
SS.SMu.CSaMu.AfilEten
The current biotope may be distinguished from SS.SMu.CSaMu.AfilEten by the differing abundances of the characterising species Amphiura filiformis and Thyasira flexuosa in the two biotopes.Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SMu.CSaMu.ThyNten | Thyasira spp. and Nuculoma tenuis in circalittoral sandy mud |
| 2004 (04.05) | SS.SMu.CSaMu.ThyNten | Thyasira spp. and Nuculoma tenuis in circalittoral sandy mud |