Description of biotope or habitat type
Verrucaria maura on very exposed to very sheltered upper littoral fringe rock
Habitat (physical) description
|Salinity||Full (30-35 ppt), Variable (18-35 ppt)|
|Wave exposure||Very exposed, Exposed, Moderately exposed, Sheltered, Very sheltered|
|Substratum||Bedrock; stable boulders; stable cobbles|
|Zone||Littoral fringe - upper|
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.
Upper littoral fringe bedrock, boulders and stable cobbles on very exposed to very sheltered shores which have a blanket covering of the black lichen Verrucaria maura. The winkle Littorina saxatilis is often present. Due to the nature of this biotope it is species poor, but occasionally a range of species may be present in low abundance. These species include the yellow lichen Caloplaca marina and the winkle Melarhaphe neritoides, the barnacles Chthamalus montagui and Semibalanus balanoides or the ephemeral seaweeds Porphyra umbilicalis and Enteromorpha spp. can be present in low abundance (see Ver.B). If one or more of these species is present compare with Ver.B. On northern shores Littorina saxatilis var. rudis can dominate along with the occasional presence of the lichens Verrucaria mucosa and Xanthoria parietina. V. maura can be found overlying stable mud in N. Ireland sea loughs.
The black lichen zone is normally found below the yellow and grey lichen zone (YG). In very sheltered areas there is not always a clear transition from one zone to the next and a mixed zone of YG and Ver.Ver is common. The wrack Pelvetia canaliculata can occur on these more sheltered shores. With increasing wave exposure the two lichen zones become wider and more distinct, and the Ver.Ver gives way to a lichen and barnacle dominated community (Ver.B) in the lower littoral fringe.
In areas with nitrate enrichment V. maura can be overgrown by the small green seaweed Prasiola stipitata (Pra) which reaches its maximum abundance during the winter months. It generally dies out during the summer in southern Britain, reverting the biotope to Ver.Ver.
|Taxon||Relative importance of taxon for defining this community (%)||Typical abundance - SACFOR scale||% of core records where taxon was recorded|
|Littorina saxatilis||7||Frequent||41-60 %|
|Verrucaria maura||87||Abundant||81-100 %|