Description of biotope or habitat type
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Melinna palmata with Magelona spp. and Thyasira spp. in infralittoral sandy mud
Physical habitat description
| Salinity | Full (30-35 ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed, Sheltered, Extremely sheltered |
| Tidal streams | Weak (>1 kn) |
| Substratum | Sandy mud |
| Zone | Infralittoral |
| Depth Band | 5-10 m, 10-20 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
In infralittoral cohesive sandy mud, in sheltered marine inlets, and occasionally variable salinity environments or coarser sediments, dense populations of the polychaete Melinna palmata may occur, often with high numbers of Magelona spp. and the bivalve Thyasira flexuosa (although the latter may be present in variable abundances or absent in some cases). Other important taxa may include Chaetozone gibber, Nephtys hombergii, Galathowenia oculata, Euclymene oerstedii, Ampelisca tenuicornis, Ampharete lindstroemi, Abra alba, and Phoronis spp. In addition the polychaete Aphelochaeta spp. and the gastropod Turritellinella tricarinata may be common or abundant in some areas. At the sediment surface visible taxa may include occasional Virgularia mirabilis, and mobile epifauna such as Pagurus bernhardus. This biotope is characteristic in many southern UK marine inlets and in some areas, e.g. Plymouth Sound, during high levels of recruitment when M. palmata often occurs in abundances between 500 to 1000 per m2 moderate numbers of the species often 'overspill' into adjacent biotopes. This biotope may also exist in a continuum with SS.SMu.CSaMu.AfilKurAnit.
Situation
In many areas this biotope is found on or near the boundary between euryhaline and polyhaline waters and in such areas moderately high numbers of Aphelochaeta spp. are often recorded.
Temporal variation
Numbers of M. palmata tend to vary considerably from year to year presumably due to recruitment and/or adult mortality.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Pagurus bernhardus | 23 | Occasional | 61-80% |
| Virgularia mirabilis | 20 | Occasional | 41-60% |
| Melinna palmata | 19 | Abundant | 81-100% |
| Myxicola infundibulum | 12 | Frequent | 41-60% |
| Mya truncata | 10 | 41-60% | |
| Chaetozone gibber | 10 | Abundant | 61-80% |
| Cerianthus lloydii | 8 | Occasional | 41-60% |
| Hydractinia echinata | 8 | Occasional | 41-60% |
| Magelona filiformis | 7 | Common | 61-80% |
| Amphiura filiformis | 5 | 41-60% | |
| Kurtiella bidentata | 5 | 41-60% | |
| Thyasira flexuosa | 5 | 41-60% | |
| Carcinus maenas | 4 | Rare | 41-60% |
| Nemertea | 4 | Common | 81-100% |
| Ampharete lindstroemi | 3 | Frequent | 61-80% |
| Euclymene oerstedii | 3 | Abundant | 61-80% |
| Galathowenia oculata | 3 | Common | 61-80% |
| Nephtys hombergii | 3 | Common | 61-80% |
| Thyasira flexuosa | 3 | Frequent | 81-100% |
| Abra alba | 2 | Common | 61-80% |
| Ampelisca tenuicornis | 2 | Common | 61-80% |
| Harpinia antennaria | 2 | Frequent | 61-80% |
| Magelona alleni | 2 | Frequent | 61-80% |
| Nucula nitidosa | 2 | 61-80% | |
| Phoronis | 2 | Common | 61-80% |
| Spio filicornis | 2 | Frequent | 61-80% |
| Nematoda | 1 | Frequent | 61-80% |
| Aphelochaeta marioni | 1 | Common | 41-60% |
| Varicorbula gibba | 1 | 61-80% | |
| Notomastus latericeus | 1 | Occasional | 61-80% |
| Phaxas pellucidus | 1 | 61-80% | |
| Tharyx | 1 | Common | 41-60% |
| Turritellinella tricarinata | 1 | Common | 41-60% |
Similar biotopes or habitat types
SS.SSa.CMuSa.AalbNuc
The current biotope displays some similarity to SS.SSa.CMuSa.AalbNuc but is found in shallower water, muddier sediments and often in estuarine influenced areas.
SS.SMu.SMuVS.AphTubi
In some areas the current biotope may resemble a more diverse, marine version of SS.SMu.SMuVS.AphTubi and it is possible that SS.SMu.ISaMu.MelMagThy occupies an intermediate position between SS.SMu.SMuVS.AphTubi and SS.SSa.CMuSa.AalbNuc.Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SMu.ISaMu.MelMagThy | Melinna palmata with Magelona spp. and Thyasira spp. in infralittoral sandy mud |
| 2004 (04.05) | SS.SMu.ISaMu.MelMagThy | Melinna palmata with Magelona spp. and Thyasira spp. in infralittoral sandy mud |
| 1997 (97.06) | Part of SS.IMS.FaMS.SpiSpi | Spio filicornis and Spiophanes bombyx in infralittoral clean or muddy sand |