Description of biotope or habitat type
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Pontocrates arenarius in littoral mobile sand
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Extremely exposed, Very exposed, Exposed, Moderately exposed |
| Tidal streams | |
| Substratum | Medium sand; fine sand |
| 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 on the mid and lower shore on wave-exposed or moderately wave-exposed coasts of medium and fine sand, sometimes with a fraction of coarse sand, which remains damp throughout the tidal cycle and contains little organic matter. The sediment is often rippled and typically lacks an anoxic sub-surface layer. The infauna is dominated by burrowing amphipods, most notably Pontocrates arenarius, as well as Bathyporeia pelagica, Haustorius arenarius and the isopod Eurydice pulchra. The polychaete fauna is poor, dominated by Scolelepis (Scolelepis) squamata, which tolerates the exposed and mobile sediment conditions. The presence of polychaetes may be seen as coloured burrows running down from the surface of the sediment.
Situation
This biotope may be present on the lower shore, where BarSa, AmSco.Eur, or AmSco.Sco are present higher up. Where AmSco.Pon occurs on the mid shore in relatively sheltered conditions, Po may be present on the lower shore. Tal may be present where driftlines of fucoids and other debris occur on the upper shore.
Temporal variation
This biotope may change to AmSco.Eur, which is very similar in character, if P. arenarius decreases in abundance. Winter storms may reduce the number of or temporarily remove macroinvertebrates from exposed sandy beaches, with the sediment becoming re-colonised during the summer months.
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 |
|---|---|---|---|---|
| Pontocrates arenarius | 62 | Common | 90 | 81-100% |
| Scolelepis squamata | 11 | Common | 39 | 21-40% |
| Eurydice pulchra | 7 | Frequent | 49 | 41-60% |
| Bathyporeia pelagica | 6 | Common | 37 | 21-40% |
| Scolelepis | 3 | Abundant | 22 | 21-40% |
| Haustorius arenarius | 2 | Common | 27 | 21-40% |
Similar biotopes or habitat types
LS.LSa.MoSa.AmSco.Eur
Occurs in similar physical environments, under slightly more sheltered conditions, and tending to be present higher up on the shore. Infauna is more sparse, dominated by E. pulchra, with P. arenarius absent.
LS.LSa.FiSa.Po.Pful
Occurs in more sheltered, occasionally estuarine, conditions, where sediments are more stable. The infauna is dominated by polychaete species, while burrowing amphipods occur less frequently.
LS.LSa.FiSa.Po.Mten
Occurs in more sheltered conditions. The sediments are even more stable than in the case of LS.LSa.FiSa.Po.Pful and therefore support bivalves, especially Macomangulus tenuis, in addition to a range of polychaete species similar to the LS.LSa.FiSa.Po.Pful assemblage. Burrowing amphipods occur less frequently than in LS.LSa.MoSa.AmSco.Pon.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | LGS.AP.Pon (part) |
| 1997 (97.06) | LGS.S.AEur (part) |
| 1997 (97.06) | LGS.S.AP.P (part) |
| 1995 | LSND.AE (part) |
| 1995 | LSND.AP (part) |
Photos
