Description of biotope or habitat type
To understand more about what this page is describing, see How to use the classification. See also How to cite.
Sponges, shade-tolerant red seaweeds and Dendrodoa grossularia on wave-surged overhanging lower eulittoral bedrock and caves
Physical habitat description
| Salinity | Full (30-35 ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Exposed, Moderately exposed, Sheltered |
| Tidal streams | |
| Substratum | Bedrock |
| Zone | Eulittoral - lower |
| Depth Band | |
| Other Features | Overhanging rock and caves |
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
Overhanging bedrock on the lower shore, at cave entrances, to and on inner walls of caves, subject to wave surge and low light levels, and characterised by a high density of small groups of the solitary ascidian Dendrodoa grossularia. The sponges Grantia compressa, Halichondria panicea and Hymeniacidon perlevis are common on the rock surface, while the hydroid Dynamena pumila (normally found on fucoids) hangs in distinct form from overhanging rock. Found on the rock surface are the calcareous tube-forming polychaetes Spirorbis spp. and Spirobranchus spp. along with the barnacles Semibalanus balanoides. The anemone Actinia equina thrives in the permanently damp pits and crevices. Where sufficient light is available a sparse community of shade-tolerant red seaweeds. These include Membranoptera alata, Lomentaria articulata, Audouinella spp. and coralline crusts.
Situation
This biotope is found on lower shore overhangs and on the entrances and inner walls of lower shore caves, and usually dominates the available habitat. It is generally found above the BarCv biotope and may extend to the upper walls of caves.
Temporal variation
Some variation in the species composition of the individual caves must be expected depending on local conditions.
Characterising species
| Taxon | Relative importance of taxon for defining this community (%) | Typical abundance - SACFOR scale | % of core records where taxon was recorded |
|---|---|---|---|
| Dendrodoa grossularia | 34 | Abundant | 81-100% |
| Halichondria panicea | 19 | Frequent | 81-100% |
| Grantia compressa | 10 | Occasional | 61-80% |
| Audouinella | 7 | Common | 41-60% |
| Corallinaceae | 5 | Occasional | 41-60% |
| Semibalanus balanoides | 4 | Common | 41-60% |
| Dynamena pumila | 4 | Frequent | 41-60% |
| Actinia equina | 2 | Occasional | 41-60% |
| Hymeniacidon perlevis | 2 | Occasional | 41-60% |
| Lomentaria articulata | 2 | Occasional | 21-40% |
| Membranoptera alata | 2 | Rare | 41-60% |
| Spirorbinae | 2 | Common | 21-40% |
Similar biotopes or habitat types
LR.FLR.CvOv.SpR
Occurs at localities with more available light. The ascidian Dendrodoa grossularia does not occur and red and brown seaweeds are usually present at higher frequency and at a higher abundance.
LR.FLR.CvOv.SpByAs
Occurs in similar physical conditions. LR.FLR.CvOv.SpByAs lacks the red seaweed community, except for a few individuals on the edge of overhangs.Classification history of this biotope or habitat type
| Classification version | Code |
|---|---|
| 1996 (6.95) | MLR.S.R |
| 1995 | LRK.RSP |
