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4 results for 'IR.LIR.K.LhypLsac'

   IR.LIR.K.LhypLsac  Mixed Laminaria hyperborea and Laminaria saccharina on sheltered infralittoral rock

Mixed Laminaria hyperborea and Laminaria saccharina on bedrock and boulders in sheltered infralittoral habitats. Typically subject to weak tidal streams and rather silty conditions. Beneath the kelp is an associated under-storey flora of foliose red seaweeds including Plocamium cartilagineum, Cryptopleura ramosa and Callophyllis laciniata as well as the brown seaweeds Dictyota dichotoma, Cutleria multifida and Desmarestia aculeata. The stipes of L. hyperborea may be densely covered with red seaweeds such as Phycodrys rubens and Delesseria sanguinea as well as the solitary ascidian Clavelina lepadiformis and the featherstar Antedon bifida. The fronds are often epiphytised by the hydroid Obelia geniculata and the bryozoan Membranipora membranacea. Beneath the kelp canopy, the faunal component is generally less diverse than the more exposed kelp forests, dominated by the echinoderms Echinus esculentus and Asterias rubens, but the tops shells Gibbula cineraria and Calliostoma zizyphinum can be common as well. The crab Necora puber and the brittlestar Ophiothrix fragilis can be found in cracks and crevices, while the tube-building polychaete Pomatoceros triqueter and coralline crusts are present on the rock surface. Although there is a reduced number of species by comparison to the more exposed L. hyperborea forests (Lhyp.Ft), there are considerably more algae species than occur in the more sheltered L. saccharina forests (Lsac.Ft). This biotope is predominately found in the shelter of fjordic sealochs in Scotland. Where it does occur in south-west Britain the mixed kelp forest may also include the southern kelp Laminaria ochroleuca. Three variants has been described: The kelp forest in the upper infralittoral (LhypLsac.Ft), grading to a kelp park with increasing depth (LhypLsac.Pk) as well as a grazed variant (LhypLsac.Gz).

   IR.LIR.K.LhypLsac.Ft  Mixed Laminaria hyperborea and Laminaria saccharina forest on sheltered upper infralittoral rock

Sheltered, often silted, upper infralittoral bedrock and boulder slopes with mixed kelps Laminaria hyperborea and Laminaria saccharina and red seaweeds beneath. The kelp at these sheltered sites often has large `cape-form' fronds, which form a dense canopy over the seabed and are often epiphytised by the hydroid Obelia geniculata and the bryozoan Membranipora membranacea. Beneath the kelp, red seaweeds such as Delesseria sanguinea and Cryptopleura ramosa occur on top of encrusting coralline algae. Often, a dense algal turf of Bonnemaisonia hamifera (tetrasporophyte) carpets the rock. The stipes of L. hyperborea may be densely covered with seaweeds such as Phycodrys rubens, Plocamium cartilagineum and Porphyropsis coccinea. There can also be a prominent faunal component on the stipes including the solitary ascidian Clavelina lepadiformis and the colonial ascidian Botryllus schlosseri. Brown seaweeds, occurring here in low abundance, include Dictyota dichotoma. The kelp Saccorhiza polyschides may also occur but rarely in equal abundance to L. hyperborea or L. saccharina. Beneath the kelp canopy, the faunal component is generally less diverse than the more exposed kelp forests (Lhyp). The silted rock supports a sparse fauna of gastropods Gibbula cineraria and Calliostoma zizyphinum, the tube-building polychaete Pomatoceros triqueter and occasional starfish Asterias rubens and the urchin Echinus esculentus. Steeper, less silted rock, may have the anthozoans Caryophyllia smithii and Alcyonium digitatum.Sheltered, often silted, upper infralittoral bedrock and boulder slopes with mixed kelps Laminaria hyperborea and Laminaria saccharina and red seaweeds beneath. The kelp at these sheltered sites often has large `cape-form' fronds, which form a dense canopy over the seabed and are often epiphytised by the hydroid Obelia geniculata and the bryozoan Membranipora membranacea. Beneath the kelp, red seaweeds such as Delesseria sanguinea and Cryptopleura ramosa occur on top of encrusting coralline algae. Often, a dense algal turf of Bonnemaisonia hamifera (tetrasporophyte) carpets the rock. The stipes of L. hyperborea may be densely covered with seaweeds such as Phycodrys rubens, Plocamium cartilagineum and Porphyropsis coccinea. There can also be a prominent faunal component on the stipes including the solitary ascidian Clavelina lepadiformis and the colonial ascidian Botryllus schlosseri. Brown seaweeds, occurring here in low abundance, include Dictyota dichotoma. The kelp Saccorhiza polyschides may also occur but rarely in equal abundance to L. hyperborea or L. saccharina. Beneath the kelp canopy, the faunal component is generally less diverse than the more exposed kelp forests (Lhyp). The silted rock supports a sparse fauna of gastropods Gibbula cineraria and Calliostoma zizyphinum, the tube-building polychaete Pomatoceros triqueter and occasional starfish Asterias rubens and the urchin Echinus esculentus. Steeper, less silted rock, may have the anthozoans Caryophyllia smithii and Alcyonium digitatum.

   IR.LIR.K.LhypLsac.Pk  Mixed Laminaria hyperborea and Laminaria saccharina park on sheltered lower infralittoral rock

Sheltered silted, bedrock and boulders with a park of mixed Laminaria hyperborea and Laminaria saccharina. Both kelp species are sparse in the park (Frequent). Beneath the often 'cape-form' kelp canopy, foliose red seaweeds such as Delesseria sanguinea, Cryptopleura ramosa, Heterosiphonia plumosa and Brongniartella byssoides are often present at high densities on the silted rock. Other red seaweeds such as encrusting coralline algae, Phycodrys rubens, Callophyllis laciniata, Bonnemaisonia asparagoides and Plocamium cartilagineum can be present. Other brown seaweeds include Dictyota dichotoma and Desmarestia aculeata. The animal component of this biotope is generally richer than the upper infralittoral mixed kelp forest (LhypLsac.Ft). A variety of hydroids such as Obelia geniculata grow epiphytically on the kelp fronds along with the bryozoan Membranipora membranacea. The echinoderm Antedon bifida and ascidians such as Clavelina lepadiformis attach to the kelp stipes, above the silted rock. The rock itself supports anthozoans such as Caryophyllia smithii and Urticina felina as well as the tube-building polychaete Pomatoceros triqueter and the crap Necora puber. Grazers include the prominent echinoderm Echinus esculentus and the gastropods Gibbula cineraria and Calliostoma zizyphinum. Where pockets of sediment occur, there may be an increase in infaunal species such as the burrowing anthozoan Cerianthus lloydii, the brittlestar Ophiura albida, and starfish Asterias rubens. Although there is a decrease in the number of algal species in the kelp park, the abundance remains relatively high.

   IR.LIR.K.LhypLsac.Gz  Grazed, mixed Laminaria hyperborea and Laminaria saccharina on sheltered infralittoral rock

Silted infralittoral rock with mixed Laminaria hyperborea and Laminaria saccharina kelp forest, intensively grazed by the echinoderm Echinus esculentus and the gastropods Gibbula cineraria and Calliostoma zizyphinum. Although both kelp species can occur in equal abundance (Common), L. hyperborea usually dominates. The grazing-resistant brown seaweed Desmarestia aculeata and Cutleria multifida may be present. A similar variety of red seaweeds to those found in the ungrazed kelp forest (LhypLsac.Ft) may occur beneath the kelp canopy, but in much lower abundance. As grazing intensity increases the seaweed cover decreases - and some sites are reduced to the bare appearance of encrusting brown and coralline algae beneath the kelp canopy. The L. hyperborea stipes generally support more seaweeds than the rock beneath, including Cryptopleura ramosa, Delesseria sanguinea, Phycodrys rubens and Bonnemaisonia hamifera. The stipes may also support sometimes dense ascidians Clavelina lepadiformis and Ciona intestinalis and the echinoderm Antedon bifida. The kelp fronds are often densely covered by the hydroid Obelia geniculata. At the most intensively grazed sites even the kelp stipes are bare. Although the rock appears bare, between boulders and in crevices there are often the brittlestar Ophiothrix fragilis and the crabs Necora puber and Pagurus bernhardus. The tube-building Pomatoceros triqueter and bryozoan crusts are commonly found on any vertical surfaces.
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