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IR.HIR.KSed.LsacSac
Laminaria saccharina and/or Saccorhiza polyschides on exposed infralittoral rock

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Habitat (physical) description

Distribution

 Salinity: Full (30-35 ppt) 
 Wave exposure: Very exposed, Exposed, Moderately exposed 
 Tidal streams: Moderately strong (1-3 kn), Weak (>1 kn) 
 Substratum: Bedrock; boulders and cobbles 
 Zone: Infralittoral 
 Depth Band: 0-5 m, 5-10 m, 10-20 m, 20-30 m 
 Other Features: Often (but not always) disturbance due to scour or seasonal instability of substratum 

Download comparative physical and biological data. The comparative tables enable a rapid comparison of the species composition and principal physical characteristics between a given set of biotopes.

Previous code

This biotope occurred in previous versions of the classification as:
EIR.LsacSpol - Version: 96.7

Distribution of habitat IR.HIR.KSed.LsacSac  Laminaria saccharina and/or Saccorhiza polyschides on exposed infralittoral rock
Distribution of habitat IR.HIR.KSed.LsacSac Laminaria saccharina and/or Saccorhiza polyschides on exposed infralittoral rock, based on records on the UK Marine Recorder database and EUSeaMap. Red dots represent records on which the biotope is based. Blue dots show other certain records, black dots show records tentatively assigned to this biotope. Yellow areas show level 2 and 3 sublittoral and deep-sea habitats prediced by EUSeaMap within UK waters.

Biotope description

A forest or park of the fast-growing, opportunistic kelps Laminaria saccharina and/or Saccorhiza polyschides often occurs on seasonally unstable boulders or sand/pebble scoured infralittoral rock. The substratum varies from large boulders in exposed areas to smaller boulders and cobbles in areas of moderate wave exposure or nearby bedrock. In these cases, movement of the substratum during winter storms prevents a longer-lived forest of Laminaria hyperborea from becoming established. This biotope also develops on bedrock where it is affected by its close proximity to unstable substrata. Other fast-growing brown seaweeds such as Desmarestia viridis, Desmarestia aculeata, Cutleria multifida and Dictyota dichotoma are often present. Some L. hyperborea plants may occur in this biotope, but they are typically small since the plants do not survive many years. The kelp stipes are usually epiphytised by red seaweeds such as Delesseria sanguinea and Phycodrys rubens. Other red seaweeds present beneath the kelp canopy include Plocamium cartilagineum, Nitophyllum punctatum, Callophyllis laciniata and Cryptopleura ramosa. Encrusting algae often form a prominent cover on the rock surfaces, including red, brown and coralline crusts. Faunal richness and diversity is generally low compared to the more stable L. hyperborea kelp forest and park communities (LhypR). Where some protection is afforded the anthozoan Alcyonium digitata can occur in addition to the more robust species such as the tube-building worm Pomatoceros triqueter. Mobile species include the to shell Gibbula cineraria and Calliostoma zizyphinum and the sea urchin Echinus esculentus. The hydroid Obelia geniculata and the bryozoan Membranipora membranacea can often be found colonising the kelp fronds.

Situation

This biotope can be found below the L. hyperborea zone (LhypFa or LhypR), especially where close to a rock/ sand interface (where it is subject to sand/pebble scour in winter). Where this biotope occurs on bedrock, not scoured by mobile sediment, it is thought to occur as a result of intense wave action in winter storms which is too severe to allow L. hyperborea to develop and remain in shallow water.

Temporal variation

Due to the disturbed nature of this biotope there can be significant changes in the structure of the community. Coralline and brown algal crusts with sparse kelp plants generally dominate areas that have been recently disturbed. Diversity is low and a few species of fast-growing seaweeds can dominate the seabed. A longer established community will have larger, mixed kelp plants and a greater diversity of red seaweeds.

Similar biotopes

IR.HIR.KSed.DesFilROccurs at similar conditions but at slightly less exposed coasts. The brown seaweed Desmarestia aculeata has a higher abundance (Abundant) than in LsacSac, while the kelp L. saccharina has a lower abundance (Occasional). The kelp S. polyschides rarely occurs.

Characterising Species

Taxa Frequency Typical Abundance % Contribution to similarity
Obelia geniculata F 2
Alcyonium digitatum O 2
Pomatoceros triqueter F 2
Gibbula cineraria O 4
Calliostoma zizyphinum O 2
Membranipora membranacea F 2
Asterias rubens O 5
Echinus esculentus O 8
Corallinaceae C 12
Callophyllis laciniata F 2
Plocamium cartilagineum F 2
Cryptopleura ramosa F 2
Delesseria sanguinea O 5
Nitophyllum punctatum O 1
Phycodrys rubens O 2
Cutleria multifida F 2
Dictyota dichotoma F 2
Desmarestia aculeata O 1
Desmarestia viridis O 1
Laminaria hyperborea C 15
Laminaria saccharina C 5
Saccorhiza polyschides C 4

Example photographs of biotope

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Version 15.03 of the classification adds a deep-sea section to version 04.05; therefore superseding version 04.05, 97.06 and 03.02.

This online classification should be cited as:

JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed]. Available from: jncc.defra.gov.uk/MarineHabitatClassification

Information from the shallower section (up to sublittoral sediment, taken from Version 04.05) be cited as the report accompanying Version 04.05, as follows:

CONNOR, D.W., J.H. ALLEN, N.GOLDING, K.L.HOWELL, L.M. LIEBERKNECHT, K.O. NORTHEN AND J.B. REKER (2004) The Marine Habitat Classification for Britain and Ireland Version 04.05. In: JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed].
Available from: jncc.defra.gov.uk/MarineHabitatClassification
ISBN 1 861 07561 8


Information from the deep-sea section (added in March 2015) should be cited as the report accompanying the deep-sea section, as follows:

PARRY, M.E.V., K.L. HOWELL, B.E. NARAYANASWAMY, B.J. BETT, D.O.B. JONES, D.J. HUGHES, N. PIECHAUD, T.D. NICKELL, H. ELLWOOD, N. ASKEW, C. JENKINS and E. MANCA (2015) A Deep-sea Section for the Marine Habitat Classification of Britain and Ireland. JNCC report 530. In: JNCC (2015) The Marine Habitat Classification for Britain and Ireland Version 15.03 [Online]. [Date accessed].
Available from: jncc.defra.gov.uk/MarineHabitatClassification
ISSN 0963 8901