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Marine Habitat Classification


4 results for 'IR.LIR.KVS'

   IR.LIR.KVS  Kelp in variable or reduced salinity

Very wave-sheltered bedrock, boulders and cobbles subject to only weak tidal streams in the sublittoral fringe and infralittoral zone, in areas of variable/reduced salinity. This biotope complex is characterised by the kelp Saccharina latissima and coralline crusts such as Lithothamnion glaciale. Grazers such as the urchins Psammechinus miliaris and Echinus esculentus, and the gastropods Steromphala cineraria and Buccinum undatum may be present. The tube-dwelling polychaete Spirobranchus triqueter, the ascidians Ciona intestinalis, Corella parallelogramma and Ascidiella scabra, the barnacle Balanus crenatus, the starfish Asterias rubens and the brittlestar Ophiothrix fragilis may also be present. Red algal communities are composed primarily of Phycodrys rubens. The crabs Carcinus maenas and Pagurus bernhardus, and the bivalve Modiolus modiolus may also be observed.

   IR.LIR.KVS.Cod  Codium spp. with red seaweeds and sparse Saccharina latissima on shallow, heavily-silted, very sheltered infralittoral rock

Very shallow, heavily-silted infralittoral rock characterised by dense stands of Codium spp., together with silt-tolerant red seaweeds, the green seaweed Ulva spp. and often only a sparse covering of the kelp Saccharina latissima. This biotope appears to have a restricted distribution, being known at present only from the sheltered voes of Shetland, some Scottish lagoons and from the harbours of south-west England. These locations suggest the habitat is likely to be subject to reduced salinity conditions (although the habitat data indicate mostly fully marine records). Dense Codium spp. can occur at very sheltered sites, on cobbles or boulders, often in dense patches interspersed with filamentous red seaweeds Bonnemaisonia hamifera, Antithamnionella spirographidis and Ceramium spp. Where sediment is present the red seaweed Polyides rotunda is commonly found along the rock-sediment interface, and the sponge Dysidea fragilis often occurs on the rock. Other red seaweeds that may be present include Chondrus crispus, Metacallophyllis laciniata, Gelidium spinosum, Corallina officinalis and coralline crusts. The brown seaweeds Halidrys siliquosa, Desmarestia viridis or Chorda filum may be present in high abundance and although kelp L. saccharina may occur, it is usually sparse. There are no conspicuous fauna that typify this biotope, though polychaetes such as terebellids and spirorbids may occur. The opisthobranch Elysia viridis may be locally abundant on the seaweeds and is known to favour Codium fragilis in particular. Large stands of Codium sp. (generally Common abundance) are accompanied by red seaweeds such as G. latifolium, C. laciniata and A. spirographidis on the rock beneath. Cod has been reported to occur in the shallows of The Fleet, Bembridge Ledges, Pagham Harbour and Jersey (Tittley et al. 1985). In Ireland, species-poor shallow, silted bedrock in the North Water of Mulroy Bay, Co. Donegal, is characterised by Griffithsia corallinoides (Common) and Codium tomentosum (Frequent) forming a narrow band below the kelp zone (Lsac.Ft). Cod has not been described from any other sites in Ireland. If Codium spp. is less than Common amongst dense L. saccharina and Chorda filum, it should not be recorded as Cod.

   IR.LIR.KVS.SlatPsaVS  Saccharina latissima and Psammechinus miliaris on variable salinity grazed infralittoral rock

Sheltered bedrock, boulders and cobbles, in areas of reduced salinity, with kelp Saccharina latissima, 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 Spirobranchus 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 Testudinalia testudinalis and the gastropod Steromphala 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 (Lsac.Ft) 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 Lsac.Ft, 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.

   IR.LIR.KVS.SlatPhyVS  Saccharina latissima with Phyllophora spp. and filamentous green seaweeds on variable or reduced salinity infralittoral rock

Shallow infralittoral bedrock or boulder slopes, in reduced or low salinity conditions, characterised by the kelp Saccharina latissima with dense stands of silted filamentous green seaweeds and red seaweeds Phyllophora crispa, Phyllophora pseudocerano??des and Phycodrys rubens. The filamentous green seaweeds e.g. Chaetomorpha melagonium and Cladophora spp. can form a blanket cover amongst the L. saccharina in the upper zone, which is under greater influence of freshwater input. In deeper water the green seaweeds are replaced by red seaweed Phyllophora spp. or Vertebrata fucoides which may form a distinct sub-zone in the biotope. Coralline crust can be present. The solitary ascidians Corella parallelogramma and Ascidiella scabra are often epiphytic on the seaweed (particularly Phyllophora spp.) and dominate the animal community along with the starfish Asterias rubens. The small ascidian Dendrodoa grossularia, the barnacle Balanus crenatus and the tube-building polychaete Spirobranchus triqueter occur on the rock surface. More mobile species include the crab Carcinus maenas, the hermit crab Pagurus bernhardus and the whelk Buccinum undatum. Bryozoans Electra pilosa and Spirorbis sp. may cover kelp fronds. The red seaweed Odonthalia dentata may be present in the north.
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