Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock
|Within Vocab||Marine Habitat Classification for Britain and Ireland Version 97.06|
|Definition||Exposed and moderately exposed kelp forest in some areas is intensely grazed by the urchin Echinus esculentus. The rock surface lacks any significant turf of foliose seaweeds and generally looks bare, though it is covered by coralline algal crusts. The kelp stipes may or may not be grazed; in the most extremely grazed areas, they too are devoid of epiphytic seaweeds. More usually, however, the stipes offer a refuge from grazing, and are characterised by dense turfs of red seaweeds, especially Phycodrys rubens, Palmaria palmata, Membranoptera alata and Delesseria sanguinea. The fauna within a grazed kelp forest is also relatively sparse, though some species will survive in cracks and crevices, or other areas that are protected from grazing. In wave-exposed steep rocky areas, the shallowest water may be characterised by a forest of kelp with red seaweeds (EIR.LhypR.Ft), with a grazed kelp forest beneath. This effect may be a result of the increased wave action in shallower water which regularly dislodges the urchins thereby reducing their impact. With increasing depth, the kelp forest grades into a grazed kelp park (MIR.LhypGz.Pk), the lower limit of which is often abrupt, which represents the balance point between urchin grazing pressure and algal growth capabilities.|
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