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Marine Habitat Classification


Description of biotope or habitat type

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   Laminaria digitata and under-boulder fauna on sublittoral fringe boulders


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed, Sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible)
Substratum Boulders
Zone Sublittoral fringe
Depth Band 0-5 m, Lower shore
Other Features Under-boulder habitats

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.

Distribution of habitat IR.MIR.KR.Ldig.Bo <I>Laminaria digitata</I> and under-boulder fauna on sublittoral fringe boulders

  • Records used to define the biotope (core records)
  • Other records assigned to this biotope, marked as 'certain'
  • Other records assigned to this biotope, marked as 'uncertain'
  • Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat

Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.

Description

This Laminaria digitata biotope is found predominantly on moderately exposed boulder shores and occasionally also on exposed or sheltered shores. Upper surfaces of the boulders are colonised by dense L. digitata though other kelp such as Laminaria hyperborea and Laminaria saccharina or the wrack Fucus serratus can be present at lower abundance. The kelp fronds can be colonised by the bryozoan Membranipora membranacea. Beneath the kelp canopy are a variety of red seaweeds such as Mastocarpus stellatus, Chondrus crispus, Palmaria palmata, Membranoptera alata, Corallina officinalis and coralline crusts. Green seaweeds include Cladophora rupestris and Ulva lactuca. Where space is available beneath the boulders (i.e. they are not buried in sediment) there may be a rich assemblage of animals. Characteristic species include the crabs Porcellana platycheles, Pisidia longicornis and juvenile Cancer pagurus. Also present beneath the boulders are often high densities of the barnacle Balanus crenatus, the tube-building polychaete Pomatoceros triqueter, spirorbid worms, the polychaete Harmotho‰ sp., gammarid amphipods and a few gastropods such as Gibbula cineraria. The encrusting bryozoans Electra pilosa and Umbonula littoralis and encrusting colonies of the sponges Halichondria panicea and Halisarca dujardini are also typical of this habitat. The richest examples also contain a variety of echinoderms such as Asterias rubens, colonial ascidians such as Botryllus schlosseri and small hydroids.

Situation

This biotope is found in a similar situation to Ldig.Ldig, usually beneath the Fucus serratus zone (Fser.Bo or Fser.R) and above the Laminaria hyperborea zone (Lhyp). Many of the animals found under boulders in the lower shore in Fser.Bo are also found under boulders in the sublittoral fringe (Ldig.Bo), particularly the sponges and crabs. Similarly, many of the seaweeds present on the lower shore are also present in the shallow sublittoral fringe.

Temporal variation

Unknown

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Halichondria panicea 5 Occasional 81-100 %
Halisarca dujardini 1 Occasional 41-60 %
Harmothoe 1 Occasional 41-60 %
Pomatoceros triqueter 4 Occasional 61-80 %
Spirorbidae 2 Frequent 41-60 %
Balanus crenatus 2 Frequent 41-60 %
Pisidia longicornis 1 Occasional 21-40 %
Porcellana platycheles 1 Occasional 21-40 %
Cancer pagurus 1 Rare 41-60 %
Gibbula cineraria 3 Occasional 61-80 %
Membranipora membranacea 1 Occasional 41-60 %
Electra pilosa 4 Occasional 61-80 %
Umbonula littoralis 1 Frequent 21-40 %
Asterias rubens 1 Occasional 41-60 %
Botryllus schlosseri 2 Occasional 41-60 %
Palmaria palmata 4 Frequent 61-80 %
Corallinaceae 10 Common 81-100 %
Corallina officinalis 2 Occasional 61-80 %
Chondrus crispus 6 Frequent 81-100 %
Mastocarpus stellatus 2 Frequent 41-60 %
Membranoptera alata 1 Occasional 41-60 %
Laminaria digitata 15 Abundant 81-100 %
Laminaria hyperborea 1 Occasional 41-60 %
Laminaria saccharina 1 Occasional 41-60 %
Fucus serratus 2 Occasional 61-80 %
Ulva lactuca 1 Occasional 41-60 %
Cladophora rupestris 2 Frequent 41-60 %

Similar biotopes

Not applicable or unknown.

Biotope history

Classification Habitat code
6.95 LRK.BSP in part
96.7 MIR.Ldig.Bo
97.06 MIR.Ldig.Ldig.Bo

Photos

IR.MIR.KR.Ldig.Bo Laminaria digitata and under-boulder fauna on sublittoral fringe boulders, St. Margarets Bay, South Foreland, Dover. David George © JNCC
IR.MIR.KR.Ldig.Bo Laminaria digitata and under-boulder fauna on sublittoral fringe boulders, St. Margarets Bay, South Foreland, Dover. David George © JNCC
IR.MIR.KR.Ldig.Bo Laminaria digitata and under-boulder fauna on sublittoral fringe boulders, Sula Skerry, Ullinish, Loch Bracadale, Skye. David Connor © JNCC
IR.MIR.KR.Ldig.Bo Laminaria digitata and under-boulder fauna on sublittoral fringe boulders, Sula Skerry, Ullinish, Loch Bracadale, Skye. David Connor © JNCC
IR.MIR.KR.Ldig.Bo Laminaria digitata and under-boulder fauna on sublittoral fringe boulders, Newhaven-west of harbour. David George © JNCC
IR.MIR.KR.Ldig.Bo Laminaria digitata and under-boulder fauna on sublittoral fringe boulders, Newhaven-west of harbour. David George © JNCC

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