Description of biotope or habitat type
Chthamalus spp. and Lichina pygmaea on steep exposed upper eulittoral rock
Habitat (physical) description
|Salinity||Full (30-35 ppt)|
|Wave exposure||Very exposed, Exposed, Moderately exposed|
|Zone||Eulittoral - upper, Littoral fringe - lower|
|Other Features||Steep sunny rock|
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.
Areas of steep and vertical rock in the upper eulittoral on very exposed to moderately exposed shores characterised by tufts of the dark brownish lichen Lichina pygmaea and the barnacles Chthamalus montagui and Chthamalus stellatus, although long-established patches of L. pygmaea ultimately exclude barnacles. The rigid branching thallus of L. pygmaea provides an ideal habitat for the bivalve Lasaea adasoni, the winkles Littorina saxatilis and Melarhaphe neritoides. The anemone Actinia equina and the mussel Mytilus edulis are confined to moist cracks and crevices, while the limpet Patella vulgata is found on the open bedrock. In the south-west the top shell Gibbula umbilicalis can be found on L. pygmaea. On the north-east coast this biotope does not have Chthamalus spp., L. pygmaea being the most important characterising species on these sites.
The band of L. pygmaea lies between the Verrucaria maura zone (Ver.B or Ver.Ver) above and the barnacle-P. vulgata zone (Sem) below. Other upper shore biotopes (Ver.B or Ver.Ver) may contain occasional patches of L. pygmaea, particularly on steep sunny faces, though not forming a distinct zone. L. pygmaea also occurs on less steeply-sloping shores if they are in a sunny aspect. In some areas, a high abundance of L. pygmaea results in a distinct zone, particularly in the south. On Chthamalus spp. dominated shores (south and west coasts) the band of L. pygmaea lies within the barnacle zone, whereas on Semibalanus balanoides dominated shores (north and east coasts) Cht.Lpyg lies astride the upper limit of the barnacles (Sem).
|Taxon||Relative importance of taxon for defining this community (%)||Typical abundance - SACFOR scale||% of core records where taxon was recorded|
|Actinia equina||2||Frequent||21-40 %|
|Chthamalus montagui||22||Common||81-100 %|
|Chthamalus stellatus||9||Frequent||81-100 %|
|Patella vulgata||15||Abundant||61-80 %|
|Littorina saxatilis||17||Common||81-100 %|
|Melarhaphe neritoides||6||Common||61-80 %|
|Mytilus edulis||3||Occasional||41-60 %|
|Lasaea adansoni||1||Occasional||21-40 %|
|Lichina pygmaea||12||Frequent||81-100 %|