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 Scrobicularia plana in littoral gravelly mud
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Very sheltered, Extremely sheltered |
| Tidal streams | |
| Substratum | Gravelly 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
Extremely sheltered gravelly mud on the mid and lower shore, containing little sand with occasional cobbles. The infaunal community includes the ragworm Hediste diversicolor and the peppery furrow shell Scrobicularia plana, as well as a range of polychaetes, oligochaetes, and molluscs. 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 HedMx.Scr and the corresponding muddy sediment biotope HedMacScr. The boundaries may be very indistinct, with HedMx.Scr present in patches of gravelly mud on areas of mudflat, where the main biotope is HedMacScr.
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 | 35 | Abundant | 558 | 81-100% |
| Scrobicularia plana | 21 | Abundant | 131 | 81-100% |
| Tubificoides pseudogaster | 20 | Abundant | 1119 | 21-40% |
| Streblospio shrubsolii | 7 | Abundant | 594 | 21-40% |
| Tubificoides benedii | 5 | Common | 797 | 41-60% |
| Macoma balthica | 3 | 13 | 21-40% | |
| Peringia ulvae | 2 | Frequent | 84 | 41-60% |
| Chaetozone vivipara | 2 | Common | 169 | 21-40% |
| Pygospio elegans | 2 | Abundant | 616 | 21-40% |
| Arenicola marina | 1 | Common | 17 | 41-60% |
| Manayunkia aestuarina | 1 | Common | 116 | 21-40% |
Similar biotopes or habitat types
LS.LMu.MEst.HedMacScr
Occurs in lower estuarine muds and sandy muds, without a gravel fraction. The infauna is dominated by the same species, but is more diverse (though that may be an artefact of greater sample numbers in the LS.LMu.MEst.HedMacScr biotope).
LS.LMx.GvMu.HedMx.Mac
Occurs lower down on the shore under more exposed conditions. The infaunal assemblage is less diverse, with fewer polychaetes and bivalves. S. plana does not occur, though Macoma balthica is abundant.
LS.LMx.GvMu.HedMx.Str
Occurs in gravelly sandy mud lower down on the shore, under more variable salinity conditions. The polychaete infauna is similar, though there may be more crustacean species, including frequent Corophium volutator, and the bivalve infauna is much reduced.
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 comparative rarity of molluscs, most notably the absence of S. plana.