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Marine Habitat Classification


Description of biotope or habitat type

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   Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed, Sheltered
Tidal streams
Substratum Bedrock
Zone Eulittoral - lower, Eulittoral - mid, Sublittoral fringe
Depth Band Lower shore
Other Features Overhanging and shaded vertical rock; Lower shore 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.

Distribution of habitat LR.FLR.CvOv.SpByAs Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves

  • 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, and shaded vertical, bedrock on the lower shore and in lower shore caves, which is not subject to appreciable wave-surge, characterised by crusts of bryozoans including Umbonula littoralis, sponges such as Grantia compressa, Halichondria panicea, Scypha ciliata and Hymeniacidon perleve and the ascidian Botryllus schlosseri. On overhangs, the hydroid Dynamena pumila hangs in distinct form from overhanging rock. The barnacles Balanus crenatus, Balanus perforatus (sometimes at high densities) and Semibalanus balanoides, and the calcareous tube-forming polychaetes Spirorbis spp. and Pomatoceros triqueter can be present as well. Certain species which are generally confined to the sublittoral, including the anemones Metridium senile and Corynactis viridis, may be found in the lower shore caves and overhangs. Littoral species such as Actinia equina are also present. The only algae present are coralline crusts. The list of characterising species partly reflects the variation in the species composition between individual overhangs and caves although this biotope can have a high species richness.

Situation

This biotope is found in the lower eulittoral and sublittoral fringe in less wave-surged conditions than that of SR.Den.

Temporal variation

Unknown.

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Scypha ciliata 1 Rare 21-40 %
Grantia compressa 3 Frequent 21-40 %
Halichondria panicea 21 Frequent 61-80 %
Hymeniacidon perleve 10 Occasional 41-60 %
Dysidea fragilis 1 Frequent 21-40 %
Porifera indet crusts 2 Occasional 21-40 %
Dynamena pumila 9 Frequent 41-60 %
Actinia equina 3 Occasional 21-40 %
Metridium senile 1 Occasional 21-40 %
Corynactis viridis 2 Occasional 21-40 %
Pomatoceros 2 Frequent 21-40 %
Pomatoceros triqueter 3 Occasional 21-40 %
Semibalanus balanoides 3 Frequent 21-40 %
Balanus crenatus 2 Occasional 21-40 %
Balanus perforatus 2 Occasional 21-40 %
Umbonula littoralis 5 Frequent 21-40 %
Bryozoa indet crusts 1 Frequent 21-40 %
Dendrodoa grossularia 1 Rare 21-40 %
Botryllus schlosseri 2 Rare 21-40 %
Corallinaceae 2 Occasional 21-40 %

Similar biotopes

LR.FLR.CvOv.SpR
SpByAs is distinguished from SR by its lack of shade-tolerant red algae, although some may occur on the edges of the overhangs.

Biotope history

Classification Habitat code
97.06 LR.SByAs
6.95 LRK.BAS
96.7 MLR.S.ByAs

Photos

LR.FLR.CVOV.SpByAs Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves, Wembury. Keith Hiscock © JNCC
LR.FLR.CVOV.SpByAs Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves, Wembury. Keith Hiscock © JNCC
LR.FLR.CVOV.SpByAs Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves, Rumbling Kern, Dunstanburgh & Craster. Jon Davies © JNCC
LR.FLR.CVOV.SpByAs Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves, Rumbling Kern, Dunstanburgh & Craster. Jon Davies © JNCC
LR.FLR.CVOV.SpByAs Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves, Cellar Beach. Keith Hiscock © JNCC
LR.FLR.CVOV.SpByAs Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves, Cellar Beach. Keith Hiscock © JNCC

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