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Marine Habitat Classification

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.


Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Very exposed, Exposed, Moderately exposed, Sheltered
Tidal streams
Substratum Bedrock
Zone Eulittoral, Littoral fringe, Supralittoral
Depth Band Lower shore, Mid shore, Upper shore
Other Features

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.Rkp Rockpools

  • 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.


Rockpools occur where the topography of the shore allows seawater to be retained within depressions in the bedrock producing 'pools' on the retreat of the tide. As these rockpool communities are permanently submerged they are not directly affected by height on the shore and normal rocky shore zonation patterns do not apply. For this reason rockpools have been dealt with as a separate biotope complex, apart from the scheme of wave exposure and shore height. Four main rockpool biotopes have been described, and although it is accepted that an enormous variety of rockpool communities exist, it is hoped that these biotope descriptions are broad enough to adequately encompass most types. It would be meaningless to include the characterising species in a description at the biotope complex level. Rockpools on the upper shore which are subject to rainwater influence and wide fluctuations in temperature are typically dominated by green seaweeds such as Ulva spp. and Cladophora spp. (G). Shallow rockpools in the mid to upper shore characterised by encrusting coralline algae and Corallina officinalis (Cor); several variants of these coralline pools occur in south-west Britain and Ireland (Cor.Par, Cor.Bif and Cor.Cys). Deeper rockpools on the mid to lower shore can support fucoids and some sublittoral species such as kelp (FK). Those rockpools influenced by the presence of sand are characterised by sand-tolerant seaweed such as Furcellaria lumbricalis and Polyides rotunda (SwSed). Where more stable sand occurs in the base of the rockpool sea-grass beds can occur (SwSed). Shallow rockpools on mixed cobbles, pebbles, gravel and sand may be characterised by hydroids (H). A very rough guideline to the terms "shallow" and "deep" rockpools: "shallow" rockpools do not support kelp, whereas "deep" rockpools do. This rockpool complex (LR.FLR.Rkp) does not include shallow standing water on compacted sediment or mixed substrata.


Rockpools occur in the littoral zone where the topography of the shore allows seawater to be retained within depressions in the bedrock producing 'pools' on the retreat of the tide.

Temporal variation

No temporal variation data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Corallinaceae 20 Abundant 61-80%
Corallina officinalis 19 Common 81-100%
Ulva intestinalis 5 Frequent 41-60%
Littorina littorea 5 Common 21-40%
Patella vulgata 5 Occasional 41-60%
Ulva lactuca 4 Occasional 41-60%
Actinia equina 3 Occasional 41-60%
Chondrus crispus 3 Occasional 41-60%
Laminaria digitata 3 Occasional 41-60%
Ceramium nodulosum 2 Frequent 21-40%
Fucus serratus 2 Occasional 21-40%
Mastocarpus stellatus 2 Occasional 21-40%
Mytilus edulis 2 Occasional 21-40%
Cladophora 1 Occasional 41-60%
Dumontia contorta 1 Occasional 21-40%
Steromphala cineraria 1 Occasional 21-40%
Palmaria palmata 1 Occasional 21-40%
Nucella lapillus 1 Occasional 21-40%

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code
1996 (6.95) RKP

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