Verrucaria mucosa and/or Hildenbrandia rubra on upper to mid shore cave walls

Description (English)

The upper walls and ceilings of the entrances and inner reaches of upper shore caves affected by direct wave action (and therefore moistened by sea spray), characterised by a mosaic of the olive green lichen Verrucaria mucosa and the non-calcified encrusting red alga Hildenbrandia rubra. The black lichen Verrucaria maura and red coralline algae can be present, though not dominating. The fauna in these upper shore caves is generally limited, due to problems of desiccation. However, where conditions remain sufficiently moist, and particularly in crevices and fissures, the barnacle Semibalanus balanoides, the limpet Patella vulgata and winkles Littorina saxatilis may occur, particularly towards the rear of the cave. Although the characterising species of this biotope also occur on the shore, they do not generally occur in a distinct band other than in moist dark caves. The turf-forming red seaweed Audouinella purpurea (syn Rhodochorton purpurea) may occasionally occur in low abundance (where A. purpurea covers an extensive area, generally on softer rock such as chalk, the biotope should be recorded as unit MA1-274).
Situation: This unit generally occurs on upper walls and ceilings towards the rear of dark, moist caves, but can also occur at cave entrances that are directly affected by sea-spray. Where this unit occurs at cave entrances and to approximately 5 m into the cave, it is usually found above a zone of unit MA1-223 and below MA1-272 or MA1-274. Further into the cave MA1-223 is replaced completely by MA1-275. There are no records for MA1-275 in soft rock caves.

Source: EUNIS habitat classification