Description of biotope or habitat type
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Mytilus edulis and piddocks on eulittoral firm clay
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Exposed, Moderately exposed |
| Tidal streams | |
| Substratum | Clay; cobbles |
| Zone | Eulittoral |
| Depth Band | Lower 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
Clay outcrops in the mid to lower eulittoral which are bored by a variety of piddocks including Pholas dactylus, Barnea candida and Petricolaria pholadiformis. The surface of the clay is characterised by small clumps of the mussel Mytilus edulis, the barnacle Austrominius modestus and the winkle Littorina littorea. Seaweeds are generally sparse on the clay, although small patches of the red seaweeds Mastocarpus stellatus, Halurus flosculosus and Ceramium spp. can occur, usually attached to loose-lying cobble or mussel shells. Also the green seaweeds Ulva spp. and Ulva lactuca may be present. The sand mason Lanice conchilega can sometimes be present in the clay, while the shore crab Carcinus maenas is present as well. More data are required to validate this description.
Situation
MytPid can usually be found beneath a M. edulis or barnacle and Littorina spp.-dominated biotope (Myt.Myt; BLitX). It is found above a Laminaria digitata and piddocks-dominated biotope (Ldig.Pid).
Temporal variation
The C. maenas population may migrate offshore during the winter season.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Mytilus edulis | 24 | Frequent | 81-100% |
| Carcinus maenas | 16 | Frequent | 81-100% |
| Barnea candida | 11 | Frequent | 41-60% |
| Ulva intestinaloides | 8 | Abundant | 41-60% |
| Ulva lactuca | 6 | Frequent | 41-60% |
| Austrominius modestus | 5 | Occasional | 41-60% |
| Littorina littorea | 5 | Frequent | 41-60% |
| Halurus flosculosus | 4 | Common | 21-40% |
| Petricolaria pholadiformis | 4 | Frequent | 21-40% |
| Mastocarpus stellatus | 2 | Occasional | 21-40% |
| Ceramium | 1 | Frequent | 21-40% |
| Lanice conchilega | 1 | Rare | 21-40% |
| Pholas dactylus | 1 | Frequent | 21-40% |
Similar biotopes or habitat types
LR.HLR.FR.RPid
Occurs on fossilised peat and chalk. It has a higher density of ephemeral seaweeds such as Ulva intestinalis and Ceramium spp. while M. edulis and E. modestus are usually absent.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | MLR.MytPid |
| 1996 (6.95) | MLR.Myt.Pid |
| 1995 | LRK.PID.CLY |