Description of biotope or habitat type
To understand more about what this page is describing, see How to use the classification. See also How to cite.
Hediste diversicolor and Streblospio shrubsolii in littoral gravelly sandy mud
Physical habitat description
| Salinity | Reduced (18-30ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | |
| Substratum | Gravelly 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
Extremely sheltered gravelly sandy mud, subject to variable salinity, on the mid and lower shore. The infaunal community consists of the ragworm Hediste diversicolor, Pygospio elegans, Streblospio shrubsolii, and Ampharete acutifrons, as well as oligochaetes and Corophium volutator. There are often low densities of Scrobicularia plana. Given the low sample numbers for this biotope, more records are needed to confirm the characterising species list.
Situation
It is probable that there are broad transition areas between this biotope and the corresponding muddy sediment biotope Hed.Str. The boundaries may be very indistinct, with HedMx.Str present in patches of gravelly mud on areas of mudflat, where the main biotope is Hed.Str. This biotope has been found along edges of tidal channels in the upper Stour estuary, below its equivalent mud biotope.
Temporal variation
Not known.
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 | 55 | Super abundant | 1719 | 81-100% |
| Oligochaeta | 20 | Common | 1332 | 81-100% |
| Streblospio shrubsolii | 14 | Common | 219 | 81-100% |
| Pygospio elegans | 5 | Common | 279 | 41-60% |
| Ampharete acutifrons | 3 | Abundant | 193 | 41-60% |
| Corophium volutator | 2 | Frequent | 39 | 61-80% |
Similar biotopes or habitat types
LS.LMu.UEst.Hed.Str
Occurs in estuarine muds, without a gravel fraction. The infauna is dominated by similar species.
LS.LMx.GvMu.HedMx.Mac
Occurs in gravelly mud under more exposed conditions. The main differences in the infaunal assemblage are the abundance of Macoma balthica, and the absence of oligochaetes and a range of polychaetes including S. shrubsolii.
LS.LMx.GvMu.HedMx.Scr
Occurs in muddy gravel, higher up on the shore and under less variable salinity conditions. The polychaete fauna is similar, but there are fewer oligochaetes. The bivalve infauna is more diverse, with more abundant S. plana.
LS.LMx.GvMu.HedMx.Cir
Occurs in slightly more exposed gravelly sandy mud. The principal differences in the infaunal assemblage are the greater abundance of Tharyx killariensis, the abundance of oligochaetes, and the absence of S. plana.