Description of biotope or habitat type
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Hediste diversicolor, Macoma balthica and Scrobicularia plana in littoral sandy mud
Physical habitat description
| Salinity | Variable (18-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed, Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | |
| Substratum | Mud or sandy mud |
| Zone | |
| Depth Band | Lower shore, Mid shore, Upper shore |
| Other Features |
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'
Point data based on records in the UK Marine Recorder Snapshot.
Description
Mainly mid shore mud or sandy mud subject to variable salinity on sheltered estuarine shores. Typically, the sediment is wet in appearance and has an anoxic layer below 1 cm depth. The surface of the mud has the distinctive 'crow's foot' pattern formed by the peppery furrow shell Scrobicularia plana. The infauna is additionally characterised by a range of polychaete and bivalve species, including the ragworm Hediste diversicolor, Pygospio elegans, Streblospio shrubsolii, Tharyx killariensis and the baltic tellin Macoma balthica. Oligochaetes, most notably Tubificoides benedii, and the spire shell Peringia ulvae may be abundant. Other species that sometimes occur in this biotope are the cockle Cerastoderma edule, the sand gaper Mya arenaria and the polychaetes Eteone longa and Nephtys hombergii.
Situation
HedMacScr may occur on the same shores as NhomMacStr, HedMac, NhomAph, Hed.Str and Hed.Cvol. Higher up on the shore, and/or further towards the head of the estuary, Hed.Ol may occur, changing to Tben at the upper extreme of the estuary.
Temporal variation
Enteromorpha spp. and Ulva lactuca may form mats on the surface of the mud during the summer months, particularly in areas of nutrient enrichment.
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 |
|---|---|---|---|---|
| Tubificoides benedii | 25 | Abundant | 2699 | 41-60% |
| Peringia ulvae | 19 | Abundant | 4118 | 81-100% |
| Hediste diversicolor | 14 | Abundant | 798 | 81-100% |
| Pygospio elegans | 8 | Common | 929 | 61-80% |
| Oligochaeta | 7 | Super abundant | 1677 | 21-40% |
| Macoma balthica | 5 | Common | 438 | 61-80% |
| Scrobicularia plana | 5 | Super abundant | 250 | 81-100% |
| Streblospio shrubsolii | 4 | Common | 392 | 41-60% |
| Tharyx killariensis | 3 | Common | 537 | 21-40% |
Similar biotopes or habitat types
LS.LMu.UEst.Hed.Ol
Tends to occur in sandier sediments, in slightly more exposed conditions, on the lower shore. There is a reduced infaunal diversity, H. diversicolor is not always present, and the cockle C. edule does not occur.
LS.LMu.UEst.NhomStr
Tends to occur lower down on slightly more exposed, marine shores, with a reduced infaunal diversity. Bivalves are absent.
LS.LMu.UEst.Hed.Str
Occurs under more sheltered estuarine conditions. The infauna is less diverse, most notably bivalve species are rare.
LS.LMu.UEst.Hed.Cvol
Tends to occur slightly higher on the shore, in more sheltered conditions. The infauna is less diverse, with lower numbers of oligochaete and polychaete species. Bivalves are virtually absent.
LS.LMu.MEst.HedMac
Occurs in similar physical conditions. S. plana is absent.
LS.LMu.MEst.NhomMacStr
Occurs further towards inner estuaries, in less saline conditions. The infauna is similar, though the ragworm H. diversicolor is often absent, and both N. hombergii and S. shrubsolii are almost always abundant. No bivalves except M. balthica occur.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 2015 (15.03) | LS.LMu.MEst.HedMacScr |
| 1997 (97.06) | LMS.SMu.HedMac (part) |
| 1997 (97.06) | LMU.SMU.HedScr |
| 1995 | LMUD.HS |
Photos
