Ephemeral seaweeds on disturbed littoral rock in the lower to upper shore. Dominant green seaweeds include Enteromorpha intestinalis, Ulva lactuca and the red seaweeds Rhodothamniella floridula and Porphyra purpurea. Winkles such as Littorina littorea and Littorina saxatilis, the limpet Patella vulgata and the barnacles Semibalanus balanoides can occur, though usually in low abundance. The crab Carcinus maenas can be found where boulders are present, while the barnacle Elminius modestus is usually present on sites subject to variable salinity. On moderately exposed shores, the biotope is Enteromorpha spp. on freshwater-influenced or unstable upper shore rock (A1.451) or P. purpurea and/or Enteromorpha spp. on sand-scoured mid to lower eulittoral rock (A1.452). These are biotopes with a low species diversity and the relatively high number of species in the characterising species list are due to a variation in the species composition from site to site, not to high species richness on individual sites. Situation: This habitat type occurs the splash zone, sometimes on cliff faces, and throughout the main intertidal zone. Note: Connor et al (2004) classify this habitat type together with A2.43 and A2.82 as LR.ELR.Eph.