Description of biotope or habitat type
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Tubularia indivisa and cushion sponges on tide-swept turbid circalittoral bedrock
Physical habitat description
| Salinity | Full (30-35 ppt) |
|---|---|
| Wave exposure | Exposed, Moderately exposed |
| Tidal streams | Very strong (>6 kn), Strong (3-6 kn) |
| Substratum | Bedrock; boulders |
| Zone | Circalittoral - lower, Circalittoral - upper |
| Depth Band | 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 variant is typically found on the vertical and upper faces of strongly tide-swept, exposed circalittoral bedrock and boulders. It is commonly associated with areas where turbidity levels are high for much of the year, for example, around Anglesey and the Lleyn Penisula. From afar, this variant appears as a dense carpet of Tubularia indivisa covering tide-swept gully walls, floors and boulders. T. indivisa is frequently observed growing through sheets of sponges such as Myxilla incrustans and Halichondria panicea as well as through dense patches of the barnacle Balanus crenatus and tubes of the amphipod Jassa spp. Several other species of sponge appear to be tolerant of the high turbidity in areas where this variant occurs, many of which are common in other biotopes. These include Amphilectus fucorum, Pachymatisma johnstonia, Hemimycale columella, Dysidea fragilis and Clathrina coriacea. Robust hydroids (other than T. indivisa) such as Nemertesia antennina and Sertularia argentea occur in patches. The anemones Urticina felina, Actinothoe sphyrodeta and Cylista elegans are typically common. A short bryozoan turf consisting of crisiid bryozoans, Alcyonidium diaphanum, Bicellariella ciliata, Bugulina turbinata and Bugulina flabellata may be present. Alcyonium digitatum may occasionally be seen although it doesn't tend to be as dominant as in CTub.Adig. Individual Corynactis viridis may be seen scattered across the gully walls and boulders. The starfish Henricia oculata may be seen on boulders and gully floors whilst typical under-boulder fauna includes the crab Cancer pagurus.
Situation
Above this biotope, Laminaria forest (LhypR) may be found.
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 |
|---|---|---|---|
| Tubularia indivisa | 17 | Abundant | 81-100% |
| Balanus crenatus | 10 | Common | 81-100% |
| Cylista elegans | 7 | Common | 61-80% |
| Actinothoe sphyrodeta | 6 | Common | 61-80% |
| Myxilla incrustans | 5 | Frequent | 61-80% |
| Alcyonium digitatum | 4 | Occasional | 61-80% |
| Amphilectus fucorum | 4 | Frequent | 61-80% |
| Pachymatisma johnstonia | 4 | Occasional | 81-100% |
| Crisiidae | 3 | Common | 41-60% |
| Hemimycale columella | 3 | Occasional | 61-80% |
| Porifera | 2 | Frequent | 41-60% |
| Alcyonidium diaphanum | 2 | Frequent | 21-40% |
| Bugulina flabellata | 2 | Common | 41-60% |
| Bugulina turbinata | 2 | Common | 41-60% |
| Corynactis viridis | 2 | Occasional | 41-60% |
| Halichondria panicea | 2 | Frequent | 41-60% |
| Henricia oculata | 2 | Occasional | 41-60% |
| Nemertesia antennina | 2 | Frequent | 41-60% |
| Bicellariella ciliata | 1 | Occasional | 41-60% |
| Cancer pagurus | 1 | Rare | 41-60% |
| Clathrina coriacea | 1 | Frequent | 41-60% |
| Dysidea fragilis | 1 | Occasional | 41-60% |
| Jassa | 1 | Frequent | 21-40% |
| Sertularia argentea | 1 | Occasional | 41-60% |
| Urticina felina | 1 | Frequent | 41-60% |
Similar biotopes or habitat types
CR.HCR.FaT.BalTub
This biotope occurs under similar conditions to CR.HCR.FaT.CTub.CuSp, although it occurs on a more mixed range of substrata than CR.HCR.FaT.CTub.CuSp. Both biotopes are dominated by a dense carpet of T. indivisa, although CR.HCR.FaT.CTub.CuSp has a more diverse sponge and bryozoan turf associated with it.
CR.HCR.FaT.CTub.Adig
This biotope occurs under similar wave-exposures to CR.HCR.FaT.CTub.CuSp although is subject to slightly weaker tidal streams than CR.HCR.FaT.CTub.CuSp. Both biotopes are dominated by a dense carpet of T. indivisa. CR.HCR.FaT.CTub.Adig does not contain such as diverse range of sponges as CR.HCR.FaT.CTub.CuSp although dead mans fingers A. digitatum are typically frequent.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1997 (97.06) | CR.ECR.BS.TubS |
Photos
