Description of biotope or habitat type
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Hediste diversicolor in littoral mud
Physical habitat description
| Salinity | Reduced (18-30ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Extremely sheltered |
| Tidal streams | |
| Substratum | Sandy mud |
| Zone | |
| Depth Band | Lower shore, Mid 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
Mud and sandy mud shores in sheltered marine inlets and estuaries subject to variable or reduced salinity. The biotope is typically found on the mid and lower shores in the upper and mid estuary. If present on the upper shore, the sediment may become firm and compacted as water drains out, though usually the biotope occurs lower on the shore and the sediment remains water saturated during low tide. An anoxic layer occurs within the upper 5 cm of the sediment. The infauna is dominated by abundant or superabundant ragworms Hediste diversicolor. Other species that occur in a significant number of samples include oligochaetes such as Baltidrilus costatus and Tubificoides spp., polychaetes such as Streblospio shrubsolii and Manayunkia aestuarina, the mud shrimp Corophium volutator, and the spire shell Peringia ulvae.
Situation
Hed may occur on the same shores as HedMac, HedMacScr, or NhomAph. Higher up on the shore, and/or further towards the upper extreme of the estuary, Tben may occur.
Temporal variation
Enteromorpha spp. and Ulva lactuca may form mats on the surface of the sediment during the summer months, particularly in areas of freshwater influence and/or where there is 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 |
|---|---|---|---|---|
| Hediste diversicolor | 45 | Super abundant | 1937 | 81-100% |
| Oligochaeta | 12 | Common | 4100 | 41-60% |
| Corophium volutator | 9 | Common | 2220 | 41-60% |
| Streblospio shrubsolii | 8 | Abundant | 1510 | 41-60% |
| Tubificoides benedii | 7 | Abundant | 2289 | 21-40% |
| Baltidrilus costatus | 5 | Abundant | 2065 | 21-40% |
| Manayunkia aestuarina | 3 | Common | 2247 | 41-60% |
| Peringia ulvae | 1 | Common | 360 | 21-40% |
| Tubificoides pseudogaster | 1 | Common | 506 | 1-20% |
Similar biotopes or habitat types
LS.LMu.UEst.NhomStr
Occurs on slightly more marine shores, in sediments with a smaller sand fraction, with a higher diversity of polychaete and oligochaete species. C. volutator is absent.
LS.LMu.MEst.HedMac
Occurs in similar physical environments. The infauna of this biotope is more diverse, most notably a range of bivalves occur, including the baltic tellin Macoma balthica, in addition to H. diversicolor and the occasionally abundant C. volutator.
LS.LMu.UEst.Tben
Occurs in slightly muddier sediments and lower salinities, further towards the head of estuaries. The species assemblage is much poorer, consisting only of oligochaetes and, in some cases, Capitella capitata. H. diversicolor does not occur.
LS.LMu.MEst.HedMacScr
Occurs in similar physical environments. The infauna of this biotope is more diverse, characterised by a range of polychaetes including the ragworm H. diversicolor and a range of bivalves including the baltic tellin M. balthica and the peppery furrow shell Scrobicularia plana.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | LMU.MU.HedOl |
| 1997 (97.06) | LMU.MU.HedStr (part) |
| 1995 | LMUD.HO (part) |