Description of biotope or habitat type
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Flustra foliacea and Haliclona oculata with a rich faunal turf on tide-swept circalittoral mixed substrata
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Exposed |
| Tidal streams | Strong (3-6 kn), Moderately strong (1-3 kn) |
| Substratum | Cobble; pebble; mud |
| Zone | Circalittoral - lower |
| Depth Band | 0-5 m, 5-10 m, 10-20 m, 20-30 m |
| 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'
- 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
This biotope is typically found on exposed slopes of silty cobble and pebble subject to strong to moderate tidal streams. From afar, large 'finger' growths of the sponge Haliclona oculata occur amongst a rich faunal turf of hydroids and bryozoans with Flustra foliacea prominent. The dense faunal turf growing on the cobbles is composed of the bryozoans F. foliacea, Alcyonidium diaphanum and Crisia eburnea and sporadic occurrences of the hydroids Nemertesia antennina, Hydrallmania falcata, Ectopleura larynx, Rhizocaulus verticillatus and Halecium halecinum. Caprellid shrimps may be observed within this faunal turf. The hard substratum frequently has a dense covering of the sponge H. oculata and occasionally Amphilectus fucorum, while the softer gravely/sand between the cobbles provides a habitat for anemones such as Urticina felina and Cerianthus lloydii. The nudibranch Antiopella cristata may be seen preying on the faunal turf and the fan worm Sabella pavonia is occasionally seen amongst the cobbles. The soft coral Alcyonium digitatum is often attached to the upper faces of more stable cobbles and rocks, while in the crevices between cobbles, the anemone Cylista elegans, the crab Cancer pagurus, the prawn Pandalus montagui and the amphipod Dyopedos porrectus may be observed. Under-cobble fauna includes terebellid worms and Harmothoe spp. This biotope has been recorded from the Menai Strait, Milford Haven and Morecambe Bay.
Situation
No situation data available.
Temporal variation
Not known
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Dyopedos porrectus | 7 | Frequent | 81-100% |
| Nemertesia antennina | 6 | Frequent | 81-100% |
| Urticina felina | 6 | Frequent | 81-100% |
| Alcyonidium diaphanum | 5 | Frequent | 81-100% |
| Alcyonium digitatum | 5 | Frequent | 81-100% |
| Cancer pagurus | 5 | Frequent | 81-100% |
| Flustra foliacea | 5 | Frequent | 81-100% |
| Haliclona oculata | 5 | Frequent | 81-100% |
| Asterias rubens | 4 | Frequent | 81-100% |
| Cylista elegans | 4 | Occasional | 81-100% |
| Seraphsidae | 4 | Occasional | 81-100% |
| Cerianthus lloydii | 3 | Occasional | 81-100% |
| Hydrallmania falcata | 3 | Occasional | 81-100% |
| Sabella pavonina | 3 | Frequent | 81-100% |
| Pycnogonida | 2 | 81-100% | |
| Balanus crenatus | 2 | Frequent | 61-80% |
| Caprellidae | 2 | 81-100% | |
| Halecium halecinum | 2 | Occasional | 81-100% |
| Pandalus montagui | 2 | Occasional | 61-80% |
| Rhizocaulus verticillatus | 2 | Occasional | 61-80% |
| Ectopleura larynx | 2 | Occasional | 81-100% |
| Crisia eburnea | 1 | Rare | 81-100% |
| Amphilectus fucorum | 1 | Occasional | 61-80% |
| Harmothoe | 1 | 81-100% | |
| Antiopella cristata | 1 | Rare | 81-100% |
Similar biotopes or habitat types
CR.HCR.XFa.Mol
This biotope occurs on shallow circalittoral bedrock and cobbles, subject to moderate exposure and moderately strong tidal streams. F. foliacea is also prevalent in this community, but has a more diverse ascidian and bryozoan community than CR.HCR.XFa.FluHocu, including Molgula manhattensis and Alcyonidium diaphanum respectively.
CR.MCR.EcCr.FaAlCr.Flu
This biotope occurs on moderately exposed circalittoral bedrock and boulders, subject to moderately strong tidal streams. This biotope is subject to considerable sand scour, and has an impoverished fauna dominated by Flustra foliacea and Alcyonium digitatum. CR.HCR.XFa.FluHocu has a higher diversity of species than CR.MCR.EcCr.FaAlCr.
CR.HCR.XFa.FluCoAs.Paur
This biotope occurs on moderately exposed bedrock, unlike CR.HCR.XFa.FluHocu which tends to occur on a cobblier substratum. This biotope does experience similar tidal stream regimes as CR.HCR.XFa.FluHocu. While F. foliacea is the dominant bryozoan, it is the presence of dense aggregations of Polyclinium aurantium which distinguish CR.HCR.XFa.FluCoAs.Paur as a separate biotope.
CR.HCR.XFa.FluCoAs
See other variants in the CR.HCR.XFa.FluCoAs biotope.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | CR.MCR.ByH.Flu.Hocu |