Description of [Laminaria hyperborea] and foliose red seaweeds on moderately exposed infralittoral rock
Moderately exposed infralittoral bedrock and boulders characterised by a canopy of the kelp Laminaria hyperborea beneath which is an under-storey of foliose red seaweeds and coralline crusts. Some red seaweeds can be found as epiphytes on the kelp stipes and include Delesseria sanguinea and Phycodrys rubens. Other red seaweeds present include the Plocamium cartilagineum, Callophyllis laciniata, Cryptopleura ramosa and the brown seaweeds Dictyota dichotoma and Cutleria multifida. The kelp fronds can be colonised by the hydroid Obelia geniculata or the bryozoans Membranipora membranacea. The echinoderm Antedon bifida, the ascidian Clavelina lepadiformis, the tube-building polychaete Pomatoceros triqueter, the anthozoans Alcyonium digitatum and Urticina felina can be found on the rock beneath the canopy. Mobile species often present include the gastropods Gibbula cineraria and Calliostoma zizyphinum and the echinoderms Echinus esculentus and Asterias rubens. Five variants has been described: Kelp forest (unit A3.2141), kelp park (unit A3.2142), grazed kelp forest (unit A3.2143), grazed kelp park (unit A3.2144) and kelp with Sabellaria spinulosa reefs (unit A3.2145). This suite of biotopes differs from the wave exposed L. hyperborea biotopes (KFaR) by having a lower diversity of cushion-forming faunal species. The foliose red seaweed component of the two suites of biotopes may also differ in composition with a tendency for A3.214 to include some more delicate filamentous species.
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