Description of [Laminaria hyperborea] forest and foliose red seaweeds on tide-swept upper infralittoral mixed substrata
Moderately wave-exposed to wave sheltered, tide-swept mixed substrata, with dense Laminaria hyperborea forest and sparser Laminaria saccharina, characterised by an under-storey and stipe flora of foliose seaweeds. The kelp stipes support epiphytes such as Palmaria palmata Callophyllis laciniata, Cryptopleura ramosa, Membranoptera alata, and Phycodrys rubens. At some sites, instead of being covered by red seaweeds, the kelp stipes are heavily encrusted by the ascidians Botryllus schlosseri and in the south-west Distomus variolosus. Epilithic seaweeds (Delesseria sanguinea, Plocamium cartilagineum, Odonthalia dentata, Dictyota dichotoma and Desmarestia aculeata) and crustose seaweeds commonly occur beneath the kelp. The kelp fronds are often covered with growth of the hydroid Obelia geniculata or the bryozoan Membranipora membranacea. Although these species are also found in most kelp forests, in this biotope they are particularly dense. On the rock surface, a rich fauna comprising anthozoans such as Urticina felina, the barnacle Balanus crenatus, the calcareous tubeworm Pomatoceros triqueter, colonial ascidians such as Clavelina lepadiformis, the gastropods Calliostoma zizyphinum and Gibbula cineraria, and the bryozoans Electra pilosa and Alcyonidium diaphanum occur. Also found on the rock are the echinoderms Echinus esculentus, Asterias rubens and Ophiothrix fragilis, and the crabs Cancer pagurus, Pagurus bernhardus and Necora puber.