Biodiversity & Conservation

For a full description of this biotope including characterizing species, distribution, survey information and references visit JNCC

Lower eulittoral and sublittoral fringe sand-scoured bedrock and boulders are often characterized by canopy algae (usually Fucus serratus), beneath which a mat of the sand-binding red alga Rhodothamniella floridula occurs. These mats can also form distinct areas without Fucus serratus. The small hummocks of Rhodothamniella floridula also contain other small red and brown algae and species of worm and amphipod may burrow into the Rhodothamniella floridula mat. Other sand-tolerant algae, such as Polyides rotundus, Furcellaria lumbricalis, Gracilaria verrucosa and Cladostephus spongiosus, may be present. Ephemeral algae such as Ulva spp., Ulva spp. and Porphyra spp. may occur. Where sand scour is more severe, fucoids and Rhodothamniella floridula may be rare or absent and these ephemeral algae dominate the substratum (MLR.EntPor - Porphyra purpurea or Ulva spp. on sand-scoured mid or lower eulittoral rock). (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

As the dominance of species varies from one to another so the colour of these populations may range from bright or dark green to various sandy, brownish-red shades, the whole contrasting sharply with adjacent areas of Fucus spp. (Lewis, 1964).