Description of biotope or habitat type
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Crepidula fornicata and Mediomastus fragilis in variable salinity infralittoral mixed sediment
Physical habitat description
| Salinity | Variable (18-35 ppt) |
|---|---|
| Wave exposure | Very sheltered, Extremely sheltered |
| Tidal streams | Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible) |
| Substratum | Mixed muddy sediment |
| Zone | Infralittoral |
| Depth Band | 0-5 m, 5-10 m, 10-20 m |
| Other Features |
Biotope origin
| Derived using data from | Various |
| Faunal group | Epifauna/infauna |
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'
- Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat
Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.
Description
Variable salinity mixed sediment characterised by the slipper limpet Crepidula fornicata and the polychaetes Mediomastus fragilis and Aphelochaeta marioni. Other numerically important taxa include the oligochaetes Tubificoides benedii, syllids such as Exogone naidinaand Sphaerosyllis, and other polychaetes Nephtys hombergii. Lepidonotus squamatus and Scoloplos armiger may also be common. Shell debris and cobbles are colonised by encrusting worms, the ascidians Ascidiella aspersa, Ascidiella scabra, Molgula sp. and Dendrodoa grossularia (the ascidians may not be recorded adequately by remote infaunal survey techniques).
Situation
This biotope occurs in the lower estuary where currents allow a stable environment to develop. It is associated with oyster beds and relict oyster beds (SS.SMx.IMx.Ost) in southern England and Wales. It may be found adjacent to or in conjunction with SS.SMu.SMuVS.AphTubi and SS.SMx.SMxVS.AphPol. It may be associated with SS.SMx.IMx.VcorAsquAps and possibly form a component of SS.SMu.ISaMu.CundAasp.
Temporal variation
No temporal data available.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Crepidula fornicata | 85 | Common | 81-100% |
| Aphelochaeta marioni | 11 | Common | 61-80% |
| Crepidula fornicata | 11 | Abundant | 81-100% |
| Mediomastus fragilis | 8 | Common | 61-80% |
| Carcinus maenas | 7 | Occasional | 21-40% |
| Tubificoides benedii | 7 | Common | 61-80% |
| Hydrozoa | 5 | 21-40% | |
| Exogone naidina | 4 | Frequent | 61-80% |
| Sphaerosyllis | 4 | Frequent | 61-80% |
| Nephtys hombergii | 3 | Common | 61-80% |
| Harmothoe impar | 2 | Common | 41-60% |
| Lepidonotus squamatus | 2 | Common | 61-80% |
| Nephtys | 2 | Common | 41-60% |
| Polydora ciliata | 2 | Common | 21-40% |
| Scoloplos armiger | 2 | Abundant | 61-80% |
| Tubificoides swirencoides | 2 | Common | 21-40% |
| Abra alba | 1 | Common | 21-40% |
| Capitella capitata | 1 | Frequent | 41-60% |
| Carcinus maenas | 1 | Abundant | 41-60% |
| Chaetozone zetlandica | 1 | Frequent | 21-40% |
| Cirriformia tentaculata | 1 | Common | 21-40% |
| Melinna palmata | 1 | Common | 41-60% |
| Tharyx killariensis | 1 | Frequent | 21-40% |
| Tubificoides pseudogaster | 1 | Frequent | 21-40% |
Similar biotopes or habitat types
SS.SMx.IMx.CreAsAn
SS.SMx.IMx.CreAsAn is found in more exposed marine areas with a lower silt content and in fully marine conditions.
SS.SMu.SMuVS.AphTubi
SS.SMx.SMxVS.CreMed may be separated from SS.SMu.SMuVS.AphTubi by the relative abundances of the slipper limpet Crepidula fornicata in addition to A. marioni.
SS.SMx.SMxVS.AphPol
SS.SMx.SMxVS.CreMed may be distinguished from SS.SMx.SMxVS.AphPol by the abundance of C. fornicata and its sediment characteristics. SS.SMx.SMxVS.AphPol may also be found in reduced salinity conditions.Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SMx.SMxVS.CreMed | Crepidula fornicata and Mediomastus fragilis in variable salinity infralittoral mixed sediment |
| 2004 (04.05) | SS.SMx.SMxVS.CreMed | Crepidula fornicata and Mediomastus fragilis in variable salinity infralittoral mixed sediment |
| 1997 (97.06) | SS.IMX.EstMx.CreAph | Crepidula fornicata and Aphelochaeta marioni in variable salinity infralittoral mixed sediment |