Description of biotope or habitat type
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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|
|Zone||Eulittoral - lower|
|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.
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.
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.
Some variation in the species composition of the individual caves must be expected depending on local conditions.
|Taxon||Relative importance of taxon for defining this community (%)||Typical abundance - SACFOR scale||% of core records where taxon was recorded|
Similar biotopes or habitat types
LR.FLR.CvOv.SpROccurs 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.SpByAsOccurs 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