⌘K
Biotope - Typologie Européenne EUNIS
B3.11 - Niveau 4 : Lichens ou petites algues vertes sur roche du supralittoral et de la frange littorale
Description
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 (B3.111) with the distinctive black band of Verrucaria maura occurring below in the littoral fringe (B3.1131, B3.1132). 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 (B3.112). The littoral fringe on soft rock can be characterised by the green seaweed Blidingia minima (B3.114) 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 (B3.115). 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.
Taxons (Liens actifs si espèces présentes)
B3.115 - Niveau 5 : Ulothrix flacca et Urospora spp. sur paroi verticale de roche tendre de la frange littorale soumise à l'action de l'eau douce
Description
An assemblage of the small un-branched filamentous green seaweeds Ulothrix flacca, Urospora penicilliformis and Urospora wormskioldii at High Water Spring Tide level on steep and vertical rock often influenced by freshwater. The community is also present in areas with freshwater seepage. It is visually recognised as a closely adherent, often shiny, green mat of filamentous growth. Associated species include the green seaweeds Blidingia minima and Enteromorpha prolifera, the barnacle Semibalanus balanoides and the limpet Patella vulgata, but these species are not common. Although this biotope does occur on rock other than chalk, this description has been derived from chalk coast sites. More information is needed to improve this description.
Situation: On chalk coasts this community can include Enteromorpha spp. and the transition from B3.115 to A1.451 is often indistinct and a mixed zone of B3.115 and A1.451 can occur.
Temporal variation: This biotope is more easily identifiable from autumn to spring as both Urospora spp. and Bangia atropurpurea may dry out and disappear during the summer. In late winter the red seaweed B. atropurpurea may be predominant and the community then appears as shiny blackish mats of filamentous growth.
Taxons (Liens actifs si espèces présentes)
Enteromorpha Link, 1820 ( Esp. caract. )
Polydora sp. ( Esp. caract. )
Ulothrix flacca (Dillwyn) Thur., 1863 ( Esp. caract. )
Ulothrix Kütz., 1833 ( Esp. caract. )
Urospora penicilliformis (Roth) Aresch., 1874 ( Esp. caract. )
Urospora wormskioldii (Mertens ex Hornem.) Rosenv., 1893 ( Esp. caract. )
Polydora sp. ( Esp. caract. )
Ulothrix flacca (Dillwyn) Thur., 1863 ( Esp. caract. )
Ulothrix Kütz., 1833 ( Esp. caract. )
Urospora penicilliformis (Roth) Aresch., 1874 ( Esp. caract. )
Urospora wormskioldii (Mertens ex Hornem.) Rosenv., 1893 ( Esp. caract. )
Analyse Ecologie du milieu (En fonction des espèces présentes)