Description of biotope or habitat type
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Nephtys hombergii and Macoma balthica in infralittoral sandy mud
Physical habitat description
| Salinity | Full (30-35 ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible) |
| Substratum | Sandy mud |
| Zone | Circalittoral, Infralittoral |
| Depth Band | 0-5 m, 5-10 m, 10-20 m |
| Other Features | Organically enriched |
Biotope origin
| Derived using data from | 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.
- 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
Near-shore shallow sandy muds and muds, and sometimes mixed sediments, may be characterised by the presence of the polychaete Nephtys hombergii and the bivalve Macoma balthica. Abra alba, and Nucula nitidosa may also be important although they may not necessarily occur simultaneously or in high numbers. Other taxa include Spiophanes bombyx, Lagis koreni, and Echinocardium cordatum. In some areas Scoloplos armiger and Crangon crangon may also be present. The community appears to be quite stable (Dewarumez et al. 1992) and the substratum is typically rich in organic content. This community has been included in the 'Boreal Offshore Muddy Sand Association' of Jones (1950) and is also described by several other authors (Petersen 1918; Cabioch & Glaçon 1975). A similar community may occur in deep water in the Baltic (Thorson 1957). This biotope may occur in slightly reduced salinity estuarine conditions where Mya sp. may become a significant member of the community (Thorson 1957).
Situation
The community may occur in small patches or swathes in shallow waters parallel to the shore (Jones 1950; Cabioch & Glaçon 1975) or in shallow nearshore depressions or trenches where finer material collects e.g. off the Suffolk coast (IECS 1991). This biotope is known to occur in patches between Denmark and the western English Channel.
Temporal variation
Sites with SS.SMu.ISaMu.NhomMac may develop into Amphiura biotopes with time (E.I.S. Rees pers. comm. 1996).
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | Typical abundance - (count per m2) | % of core records where taxon was recorded |
|---|---|---|---|---|
| Nephtys hombergii | 37 | Common | 57 | 81-100% |
| Macoma balthica | 20 | Frequent | 41 | 61-80% |
| Nucula nitidosa | 18 | Frequent | 109 | 41-60% |
| Abra alba | 6 | 13 | 41-60% | |
| Echinocardium cordatum | 3 | 16 | 21-40% | |
| Lagis koreni | 3 | 9 | 21-40% | |
| Spiophanes bombyx | 3 | 11 | 21-40% | |
| Ophiura ophiura | 2 | 9 | 21-40% | |
| Magelona mirabilis | 1 | 4 | 1-20% |
Similar biotopes or habitat types
SS.SSa.CMuSa.AalbNuc
In deeper, less muddy areas SS.SMu.ISaMu.NhomMac may grade into SS.SSa.CMuSa.AalbNuc and it is possible that this biotope is part of the Abra dominated muddy sand biotopes.Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SMu.ISaMu.NhomMac | Nephtys hombergii and Macoma balthica in infralittoral sandy mud |
| 2004 (04.05) | SS.SMu.ISaMu.NhomMac | Nephtys hombergii and Macoma balthica in infralittoral sandy mud |
| 1997 (97.06) | SS.IMS.FaMS.MacAbr | Macoma balthica and Abra alba in infralittoral muddy sand or mud |
| 1996 (6.95) | IMS.AbrLag |