Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock

English name: Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock

Quick facts

EUNIS habitat type code A3.2143
Bern Convention Included in a Resolution 4 habitat type at a higher level (A3)

Description (English)

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, Callophyllis 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 Laminaria saccharina 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 Pomatoceros triqueter are resistant to grazing and may occur in abundance. The grazers present include the echinoderm Echinus esculentus and the gastropods Calliostoma zizyphinum and Gibbula 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.
Situation: With increasing depth, the kelp forest grades into a grazed kelp park (unit A3.2144), the lower limit of which is often abrupt, representing the balance point between urchin-grazing pressure and kelp growth capabilities. In wave-exposed steep rocky areas, the shallowest water may be characterised by a forest of kelp with red seaweeds (unit A3.1151), 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 grazing impact. This unit is prevalent in the north of the UK where E. esculentus populations reach high densities. Although E. esculentus is widely distributed around the UK it occurs in greatest abundance in Scotland and north-east England where urchin grazing can substantially affect infralittoral communities.
Temporal variation: Fluctuations in E. esculentus numbers may give foliose seaweeds a chance to re-grow periodically. Further information is required on the temporal variation within these grazed forests and the changes in community structure when grazing pressure decreases.

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Algae Cruoria pellita
Algae Cutleria multifida
Algae Delesseria sanguinea
Algae Laminaria hyperborea
Algae Laminaria saccharina
Algae Phycodrys rubens
Algae Plocamium cartilagineum
Invertebrates Alcyonium digitatum
Invertebrates Antedon bifida
Invertebrates Asterias rubens
Invertebrates Calliostoma zizyphinum
Invertebrates Clavelina lepadiformis
Invertebrates Echinus esculentus
Invertebrates Gibbula cineraria
Invertebrates Membranipora membranacea
Invertebrates Obelia geniculata
Invertebrates Pomatoceros triqueter
Invertebrates Urticina felina
Species scientific name English common name Species group
Cruoria pellita Algae
Cutleria multifida Algae
Delesseria sanguinea Algae
Laminaria hyperborea Algae
Laminaria saccharina Algae
Phycodrys rubens Algae
Plocamium cartilagineum Algae
Alcyonium digitatum Invertebrates
Antedon bifida Invertebrates
Asterias rubens Invertebrates
Calliostoma zizyphinum Invertebrates
Clavelina lepadiformis Invertebrates
Echinus esculentus Invertebrates
Gibbula cineraria Invertebrates
Membranipora membranacea Invertebrates
Obelia geniculata Invertebrates
Pomatoceros triqueter Invertebrates
Urticina felina Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 IR.MIR.KR.Lhyp.GzFt Grazed <I>Laminaria hyperborea</I> forest with coralline crusts on upper infralittoral rock source
CORINE Land Cover 5.2.3. Sea and ocean n/a
For relation to plant communities (syntaxa), see Vegetation types

History

Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200410 A3.2143 Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock same
EUNIS Habitat Classification 200308 A3.221 Grazed Laminaria hyperborea with coralline crusts on infralittoral rock wider
EUNIS Habitat Classification 200308 A3.2211 Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock same
EUNIS Habitat Classification 200202 A3.2211 Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock same
EUNIS Habitat Classification 199910 A3.2211 Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock same
MNCR BioMar 97.06 (Britain & Ireland) MIR.GzK.LhypGz.Ft Grazed Laminaria hyperborea forest with coralline crusts on upper infralittoral rock same
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