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Marine Habitat Classification


Description of biotope or habitat type

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   Green algal films on upper and mid-shore cave walls and ceilings


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed, Sheltered
Tidal streams
Substratum Bedrock
Zone Eulittoral - mid, Eulittoral - upper, Littoral fringe, Supralittoral
Depth Band
Other Features Moist, dark 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.GCv Green algal films on upper and mid-shore cave walls and ceilings

  • 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

The upper walls and ceilings of upper and mid-shore hard and soft rock (chalk) dominated by a band of green algal films (or 'stains'). Other encrusting algae including the non-calcified Hildenbrandia rubra may be present. In chalk caves, on the east and south-east coasts of England, a distinctive assemblage of species occurs, including the brown alga Pilinia maritima and the bright green algae Pseudendoclonium submarinum and Entocladia perforans that often covers the cave ceilings. Fauna is generally sparse and limited to limpets such as Patella vulgata and the winkle Littorina saxatilis. The species forming a green algal film that covers upper shore caves in Berwickshire were not identified. More information required to validate this biotope description.

Situation

This biotope is situated above the AudCla or VmucHil zone, extending to cover the upper walls and ceilings of caves. GCv can be found at the entrances to caves and through to the darkest areas at the back and is often found above a zone of AudPil. In hard rock caves however, the green and brown algae (AudPil) or Haptophyceae (ChrHap) occur as separate zones or GCv may occur on its own.

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
Patella vulgata 3 Frequent 21-40 %
Littorina saxatilis 3 Frequent 21-40 %
Hildenbrandia rubra 13 Super abundant 21-40 %
Chlorophycota 70 Super abundant 81-100 %

Similar biotopes

Not applicable or unknown.

Biotope history

Classification Habitat code
96.7 SUR.PilPse

Photos

LR.FLR.CVOV.GCv Green algal films on upper and mid-shore cave walls and ceilings, Buckton Cliffs, Flamborough Head. Rohan Holt © JNCC
LR.FLR.CVOV.GCv Green algal films on upper and mid-shore cave walls and ceilings, Buckton Cliffs, Flamborough Head. Rohan Holt © JNCC
LR.FLR.CVOV.GCv Green algal films on upper and mid-shore cave walls and ceilings, Rockall, SW side. Keith Hiscock © JNCC
LR.FLR.CVOV.GCv Green algal films on upper and mid-shore cave walls and ceilings, Rockall, SW side. Keith Hiscock © JNCC

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