Lichens or small green algae on Atlantic supralittoral and littoral fringe rock

Description (English)

Lichen communities typically form a distinct zone or band in a 'splash' zone on most rocky shores. This splash zone occurs above the main intertidal zone (i.e. that subject to regular covering by the tide) and blends into angiosperm-dominated communities of coastal (terrestrial) habitats at its upper limits. The width of the splash zone varies considerably, depending on the degree of exposure of the shore to wave action. On very exposed coasts the zone is very wide, extending 10s of meters up cliffs, whilst in very sheltered sites it may be only a metre or so high. Several biotopes have been identified. Yellow and grey lichens such as Xanthoria parietina, Caloplaca marina, Caloplaca thallincola or Ramalina sp. dominate the supralittoral rock (MA1-211) with the distinctive black band of Verrucaria maura occurring below in the littoral fringe (MA1-2131, MA1-2132). Small green seaweeds can sometimes be found in this splash zone, where localised conditions allow growth in what would otherwise be inhospitable conditions for seaweeds. Such an example is the green seaweed Prasiola stipitata which occurs in areas of nitrate enrichment from nearby roosting seabirds (MA1-212). The littoral fringe on soft rock can be characterised by the green seaweed Blidingia minima (MA1-214) while steep and vertical rock influenced by freshwater in the littoral fringe can be dominated by the green seaweeds Ulothrix flacca, Urospora penicilliformis and Urospora wormskioldii (MA1-215). The winkle Littorina saxatilis is one of the few 'marine' species found in this environment.
Situation: This habitat type is found in the littoral fringe and the supralittoral zone on all rocky shores if there is sufficient seawater spray to maintain a viable community.

Source: EUNIS habitat classification