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Marine Habitat Classification


Description of biotope or habitat type

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   Sponges and shade-tolerant red seaweeds on overhanging lower eulittoral bedrock and in cave entrances


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed, Sheltered
Tidal streams
Substratum Bedrock
Zone Eulittoral - lower, Eulittoral - mid, Sublittoral fringe
Depth Band
Other Features Overhanging rock and cave entrances

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.SpR Sponges and shade-tolerant red seaweeds on overhanging lower eulittoral bedrock and in cave entrances

  • 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 shaded bedrock on the open lower shore and at the entrance to inner reaches of caves (where light availability permits), which is not subject to appreciable wave-surge, characterised by a shade-tolerant red seaweed community. It includes foliose species such as Plumaria plumosa, Palmaria palmata, Mastocarpus stellatus, Membranoptera alata and Osmundea pinnatifida, but Lomentaria articulata and coralline crusts are usually present as well. The foliose green seaweed Ulva lactuca can be present. The rock surface often supports dense populations of calcareous tube-forming polychaetes Spirorbis spp. and Pomatoceros spp., while sponges such as Grantia compressa, Halichondria panicea and Hymeniacidon perleve can be common. The hydroid Dynamena pumila (normally found on fucoids) hangs in distinct form from overhanging rock. Colonies of the ascidian Botryllus schlosseri can be found on the rock, along with the mussel Mytilus edulis and the barnacles Semibalanus balanoides and Balanus perforatus (the latter may occur at high densities in the south and west), while the anemone Actinia equina thrives in the permanently damp pits and crevices. The whelk Nucella lapillus can be found among the barnacles and mussels, preying on them. The long list of characterising species is partly due to the difference in the species composition and does not solely reflect a high species richness.

Situation

On overhangs, this biotope is generally found above the SByAs biotope, where there is more light available. In cave environments, SR may be found at the entrance to and inner reaches of the cave, extending from the lower walls (above the SByAs biotope) to the upper walls (depending on the height of the cave). Further into the cave where less light is available the ascidian Dendrodoa grossularia can be abundant (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
Grantia compressa 3 Occasional 21-40 %
Halichondria panicea 15 Frequent 81-100 %
Hymeniacidon perleve 5 Occasional 41-60 %
Dynamena pumila 5 Frequent 41-60 %
Actinia equina 2 Occasional 21-40 %
Pomatoceros 2 Occasional 21-40 %
Spirorbidae 3 Frequent 41-60 %
Semibalanus balanoides 5 Frequent 41-60 %
Balanus perforatus 2 Frequent 21-40 %
Nucella lapillus 2 Occasional 21-40 %
Mytilus edulis 2 Occasional 21-40 %
Umbonula littoralis 1 Occasional 21-40 %
Palmaria palmata 4 Occasional 41-60 %
Corallinaceae 8 Common 41-60 %
Lomentaria articulata 9 Common 61-80 %
Plumaria plumosa 8 Frequent 61-80 %
Membranoptera alata 2 Occasional 21-40 %
Osmundea pinnatifida 3 Frequent 41-60 %
Mastocarpus stellatus (petrocelis) 2 Frequent 21-40 %
Ulva lactuca 2 Occasional 41-60 %

Similar biotopes

LR.FLR.CvOv.SpByAs
SR is distinguished from SByAs by its abundance of red algae; SByAs lacks the red algae, except for perhaps a few on the edge of the overhang.

Biotope history

Classification Habitat code
97.06 LR.SR
6.95 LRK.RSP
96.7 MLR.S.R

Photos

LR.FLR.CVOV.SpR Sponges and shade-tolerant red seaweeds on overhanging lower eulittoral bedrock and in cave entrances, Rumbling Kern, Dunstanburgh & Craster. Jon Davies © JNCC
LR.FLR.CVOV.SpR Sponges and shade-tolerant red seaweeds on overhanging lower eulittoral bedrock and in cave entrances, Rumbling Kern, Dunstanburgh & Craster. Jon Davies © JNCC
LR.FLR.CVOV.SpR Sponges and shade-tolerant red seaweeds on overhanging lower eulittoral bedrock and in cave entrances, N of Bay of Deepdale, Scapa Flow. Eleanor Murray © JNCC
LR.FLR.CVOV.SpR Sponges and shade-tolerant red seaweeds on overhanging lower eulittoral bedrock and in cave entrances, N of Bay of Deepdale, Scapa Flow. Eleanor Murray © JNCC

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