The littoral fringe zone occurs between the supralittoral and eulittoral zones and in some cases is considered a terrestrial habitat i.e. within the EUNIS classification it is placed with the coastal habitats and the supralittoral and littoral fringe lichen communities come under the one broad habitat complex, Lichens or small green algae on supralittoral and littoral fringe rock B3.11.
The littoral fringe receives the salt spray from the waves, as such, those shores experiencing greater exposure and salt spray from waves have larger littoral fringe zones. Rock altitude, angle, shade and local climate also influence the extent of the zone. These factors also effect the distinction between the supralittoral and littoral fringe communities so that sometimes they are distinct or are intermingled.
The littoral fringe zone is often characterised by rocks covered in the black tar lichen (Verrucaria maura), rough periwinkles, channel wrack, ephemeral seaweeds, sparse barnacles and pools with variable salinity and temperatures.
Other organisms that come under the broad lichen habitat complex (LR.FLR.Lic) that are also characteristic of littoral fringe communities are green seaweeds such as Blidingia sp, Ulothrix sp and Urospora sp that can characterise areas of littoral fringe soft rock or vertical rock where there is fresh water run off.
The organisms living in this zone are highly specialized to endure variable salinity and extended periods of air exposure.
A characteristic species of the lower littoral fringe rock of some shores is channel wrack (Pelvetia canaliculata) and on moderately exposed shores an accompanying spare barnacle community. Habitat classification: LR.MLR.BF.PelB (Pelvetia canaliculata and barnacles on moderately exposed littoral fringe rock) EUNIS: A1.211.
P. canaliculata cover increases on sheltered shores and the there is no associated barnacle community. Habitat classification: LR.LLR.F.Pel (Pelvetia canaliculata on sheltered littoral fringe rock) EUNIS: A1.321.