Description of biotope or habitat type
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Maerl beds
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed, Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible) |
| Substratum | Gravels, clean sands |
| 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 |
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
Beds of maerl in coarse clean sediments of gravels and clean sands, which occur either on the open coast or in tide-swept channels of marine inlets (the latter often stony). In fully marine conditions the dominant maerl is typically Phymatolithon calcareum (SS.SMp.Mrl.Pcal), whilst under variable salinity conditions in some sea lochs beds of Lithothamnion glaciale (SS.SMp.Mrl.Lgla) may develop.
Situation
No situation data available.
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 |
|---|---|---|---|
| Phymatolithon calcareum | 15 | Common | 61-80% |
| Asterias rubens | 10 | Occasional | 61-80% |
| Nematoda | 9 | Common | 81-100% |
| Metaphoxus fultoni | 7 | Common | 61-80% |
| Grania | 6 | Abundant | 41-60% |
| Pagurus bernhardus | 6 | Occasional | 61-80% |
| Chone duneri | 5 | Common | 61-80% |
| Saccharina latissima | 5 | Occasional | 41-60% |
| Amphipholis squamata | 4 | Super abundant | 61-80% |
| Dictyota dichotoma | 4 | Occasional | 41-60% |
| Psamathe fusca | 4 | 81-100% | |
| Mediomastus fragilis | 4 | Frequent | 81-100% |
| Socarnes erythrophthalmus | 4 | Abundant | 41-60% |
| Animoceradocus semiserratus | 3 | Common | 41-60% |
| Cerianthus lloydii | 3 | Frequent | 41-60% |
| Cumella (Cumella) pygmaea | 3 | Common | 41-60% |
| Leptocheirus pectinatus | 3 | Abundant | 41-60% |
| Onoba aculeus | 3 | Super abundant | 41-60% |
| Plocamium cartilagineum | 3 | Occasional | 41-60% |
| Polycirrus | 3 | Common | 61-80% |
| Chaetopterus variopedatus | 2 | Occasional | 21-40% |
| Cymodoce truncata | 2 | 41-60% | |
| Dikoleps nitens | 2 | Abundant | 41-60% |
| Megamphopus cornutus | 2 | Frequent | 41-60% |
| Steromphala cineraria | 2 | Occasional | 21-40% |
| Lanice conchilega | 2 | Occasional | 21-40% |
| Leptocheirus hirsutimanus | 2 | Frequent | 41-60% |
| Liocarcinus depurator | 2 | Occasional | 41-60% |
| Nannastacus unguiculatus | 2 | Common | 41-60% |
| Nemertea | 2 | 41-60% | |
| Spirobranchus triqueter | 2 | Occasional | 21-40% |
| Sphaerosyllis taylori | 2 | Frequent | 41-60% |
| Vaunthompsonia cristata | 2 | 61-80% | |
| Echinus esculentus | 2 | Occasional | 21-40% |
| Aonides paucibranchiata | 1 | 61-80% | |
| Austrosyrrhoe fimbriatus | 1 | Common | 21-40% |
| Vertebrata byssoides | 1 | Occasional | 21-40% |
| Chorda filum | 1 | Frequent | 21-40% |
| Desmarestia viridis | 1 | Occasional | 21-40% |
| Eurysyllis tuberculata | 1 | Common | 41-60% |
| Gibbula magus | 1 | Occasional | 21-40% |
| Harmothoe impar | 1 | Common | 61-80% |
| Lithothamnion glaciale | 1 | Frequent | 21-40% |
| Neopentadactyla mixta | 1 | Occasional | 21-40% |
| Phycodrys rubens | 1 | Occasional | 21-40% |
| Bonnemaisonia hamifera | 1 | Frequent | 21-40% |
| Pseudosyllis brevipennis | 1 | Frequent | 41-60% |
Similar biotopes or habitat types
Not applicable or unknown.
Classification history of this biotope or habitat type
| Classification version | Code | Habitat name |
|---|---|---|
| 2015 (15.03) | SS.SMp.Mrl | Maerl beds |
| 2004 (04.05) | SS.SMp.Mrl | Maerl beds |
| 1997 (97.06) | SS.IGS.Mrl and SS.IMX.MrlMx | Maerl beds (open coast/clean sediments) and Maerl beds (muddy mixed sediments) |