Laminaria saccharina and Psammechinus miliaris on variable salinity grazed infralittoral rock

English name: Laminaria saccharina and Psammechinus miliaris on variable salinity grazed infralittoral rock

Quick facts

EUNIS habitat type code A3.322
Bern Convention Included in a Resolution 4 habitat type at a higher level (A3)

Description (English)

Sheltered bedrock, boulders and cobbles, in areas of reduced salinity, with kelp Laminaria saccharina, and depauperate coralline-encrusted rock supporting few foliose seaweeds but many grazing urchins Psammechinus miliaris and Echinus esculentus. The coralline crusts are typically Lithothamnion glaciale, while the brown crusts can be Pseudolithoderma extensum. Encrusting polychaetes Pomatoceros triqueter, resistant to the grazing, are also present on most of the rock. The grazing fauna are a significant component of this biotope; large numbers of P. miliaris are typically present, although where absent the brittlestar Ophiothrix fragilis may occur. Other grazers prevalent on the rock include the chiton Tonicella marmorea, the limpet Tectura testudinalis and the gastropod Gibbula cineraria. A combination of grazing pressure and lowered salinity maintains a low diversity of species in this biotope, with foliose and filamentous seaweeds generally absent or reduced to small tufts by grazing. In stark contrast to the range of seaweeds present in the L. saccharina forests (A3.3132) the only red seaweed consistently found in this biotope is Phycodrys rubens. The range of fauna is similarly low, with a conspicuous absence of hydroids and bryozoans. Bedrock and boulders provide a firm substrate on which ascidians Ciona intestinalis and Ascidia mentula and the bivalve Modiolus modiolus can attach. The crabs Pagurus bernhardus and Carcinus maenas can usually be found here, though Necora puber typically is absent due to the brackish conditions. The starfish Asterias rubens along with the whelk Buccinum undatum can be present. The substratum on which this biotope occurs varies from bedrock to boulders or cobbles on sediment. The kelp band is relatively narrow and shallow (upper 5 m) compared to unit A3.3121, although the grazed coralline encrusted rock extends deeper. This depth limit becomes shallower towards the heads of the sealochs. Geographical distribution This biotope is restricted to the west coast of Scotland, usually near the head of fjordic sealochs, which are influenced by freshwater run-off.
Situation: Where circalittoral rock occurs below this biotope, it often supports a brachiopod/anthozoan community (unit A4.314); where mixed substrata occurs below or adjacent, beds of Modiolus modiolus are common (units A5.623 or A5.442).
Temporal variation: If the grazing pressure is reduced (i.e. a decrease in the number of grazing echinoderms present) there may be an increase in filamentous and foliose seaweeds although the diversity will remain low compared to full saline sites.

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Invertebrates Ascidia mentula
Invertebrates Asterias rubens
Invertebrates Buccinum undatum
Invertebrates Carcinus maenas
Invertebrates Ciona intestinalis
Invertebrates Echinus esculentus
Invertebrates Gibbula cineraria
Algae Laminaria saccharina
Algae Lithothamnion glaciale
Invertebrates Modiolus modiolus
Invertebrates Necora puber
Invertebrates Ophiothrix fragilis
Invertebrates Pagurus bernhardus
Algae Phycodrys rubens
Invertebrates Pomatoceros triqueter
Invertebrates Psammechinus miliaris
Algae Pseudolithoderma extensum
Invertebrates Tectura testudinalis
Invertebrates Tonicella marmorea
Species scientific name English common name Species group
Ascidia mentula Invertebrates
Asterias rubens Invertebrates
Buccinum undatum Invertebrates
Carcinus maenas Invertebrates
Ciona intestinalis Invertebrates
Echinus esculentus Invertebrates
Gibbula cineraria Invertebrates
Laminaria saccharina Algae
Lithothamnion glaciale Algae
Modiolus modiolus Invertebrates
Necora puber Invertebrates
Ophiothrix fragilis Invertebrates
Pagurus bernhardus Invertebrates
Phycodrys rubens Algae
Pomatoceros triqueter Invertebrates
Psammechinus miliaris Invertebrates
Pseudolithoderma extensum Algae
Tectura testudinalis Invertebrates
Tonicella marmorea Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 IR.LIR.KVS.LsacPsaVS <I>Laminaria saccharina</I> and <I>Psammechinus miliaris</I> on variable salinity grazed 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 A3.322 Laminaria saccharina and Psammechinus miliaris on variable salinity grazed infralittoral rock same
EUNIS Habitat Classification 200308 A3.3142 Laminaria saccharina and Psammechinus miliaris on reduced salinity grazed infralittoral rock same
EUNIS Habitat Classification 200202 A3.3142 Laminaria saccharina and Psammechinus miliaris on reduced salinity grazed infralittoral rock same
EUNIS Habitat Classification 199910 A3.3142 Laminaria saccharina and Psammechinus miliaris on reduced salinity grazed infralittoral rock same
MNCR BioMar 97.06 (Britain & Ireland) SIR.K.LsacRS.Psa Laminaria saccharina and Psammechinus miliaris on reduced salinity grazed infralittoral rock same
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Denmark
Phone: +45 3336 7100