Description of Sparse [Laminaria hyperborea] and dense [Paracentrotus lividus] on exposed infralittoral limestone
This biotope is known from only one location, the Aran Islands, Co. Galway (Ireland). Here, a limestone platform between 3 m and 6 m of depth is dominated by a dense population of the urchin Paracentrotus lividus, which heavily graze and burrow into the soft limestone. So intense is the grazing pressure that the rock appears completely bare, except for a coralline algal crust and occasional Laminaria hyperborea and Saccorhiza polyschides. The anthozoans Sagartia elegans and Corynactis viridis are also present, though at low abundance. The grazed kelp also extends deeper to 20 to 25 m further offshore. (Only one CB record within this biotope). Situation: This rare biotope has only been recorded from one location and the neighbouring biotopes were not fully surveyed. In deeper water (30-40m) there is unit A4.121.