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Marine Habitat Classification


1 result for 'IR.MIR.KR.Lhyp.GzFt'

   IR.MIR.KR.Lhyp.GzFt  Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock

Exposed to moderately exposed Laminaria hyperborea forest is in some areas intensely grazed by the urchin Echinus esculentus. The rock surface lacks a significant turf of foliose seaweeds and generally looks bare, though encrusting algae cover the rock. In addition to these encrusting coralline algae, non-calcareous crusts such as Cruoria pellita and brown algal crusts also occur. The kelp stipes may or may not be grazed; in the most extremely grazed areas, the stipes are also devoid of seaweeds. More usually, however, the stipes offers a refuge from grazing, and are characterised by dense turfs of red seaweeds, especially Phycodrys rubens, Metacallophyllis laciniata, Plocamium cartilagineum and Delesseria sanguinea. The hydroid Obelia geniculata and the bryozoan Membranipora membranacea colonise the kelp fronds. On the rock itself certain brown seaweeds such as Cutleria multifida may persist in this grazed environment. Fast-growing species such as the kelp Saccharina latissima may be present at sites recovering from grazing, opportunistically colonising the rock surfaces that have been cleared by grazing. The fauna within a grazed kelp forest is also relatively sparse and is mostly confined to cracks, crevices and under-boulders. Species such as the ascidian Clavelina lepadiformis can often be found on vertical rock. Also found on the rock surface are the anthozoans Urticina felina and Alcyonium digitatum. Encrusting species such as the tube-building polychaete Spirobranchus triqueter are resistant to grazing and may occur in abundance. The grazers present include the echinoderm Echinus esculentus and the gastropods Calliostoma zizyphinum and Steromphala cineraria. Other echinoderms present include Asterias rubens and Antedon bifida which can be abundant in the north-west. Moderate grazing occurs within many kelp forests; records should only be assigned to this biotope where the community has been intensively grazed leaving algal-encrusted rock with very few epilithic algae.
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