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Marine Habitat Classification


Description of biotope or habitat type

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   Fucus serratus and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders


Habitat (physical) description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed, Sheltered
Tidal streams
Substratum Boulders
Zone Eulittoral - lower
Depth Band
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 LR.MLR.BF.Fser.Bo <I>Fucus serratus</I> and under-boulder fauna on exposed to moderately exposed lower eulittoral 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'

Point data based on records in the UK Marine Recorder Snapshot.

Description

Exposed to moderalety exposed lower eulittoral boulders with the wrack Fucus serratus community of a high species richness as the presence of the boulders increases the micro-habitat diversity. The upper surfaces of the boulders are colonised by a very similar fauna to the other F. serratus biotopes, including species such as the limpet Patella vulgata, the whelk Nucella lapillus, the anemone Actinia equina and the barnacle Semibalanus balanoides. The shaded sides of the boulders are, depending on environmental conditions, often colonised by a variety of foliose red seaweeds, including Mastocarpus stellatus, Lomentaria articulata, Osmundea pinnatifida, Palmaria palmata and Chondrus crispus. Coralline algae such as Corallina officinalis and coraline crusts, as well as the green seaweeds Enteromorpha intestinalis and Ulva lactuca, can be found underneath the F. serratus canopy or in patches on the boulders. The species composition underneath the boulders varies considerably depending on the underlying substratum. On muddy shores the fauna living under the boulders may be limited to a few infaunal species, such as the polychaete Cirratulus cirratus. Where more space is available beneath the boulders there may be a rich assemblage of animals. Characteristic mobile species include the crabs Porcellana platycheles and Carcinus maenas. Also present on and beneath the boulders are the tube-forming polychaete Pomatoceros triqueter, spirorbid polychaetes and a few winkles such as Littorina obtusata/mariae and Littorina littorea or even the top shell Gibbula cineraria. Encrusting colonies of the sponge Halichondria panicea are also typical of the undersides of boulders, while the hydroid Dynamena pumila colonies can be found on the F. serratus fronds. The richest examples of this biotope also contain a variety of brittlestars, ascidians and small hydroids.

Situation

This biotope usually occurs immediately below a Fucus vesiculosus-barnacle mosaic (FvesB) on moderately exposed shores or a dense canopy of F. vesiculosus (Fves) or Ascophyllum nodosum (Asc.FS) on sheltered shores. The sublittoral fringe below on moderately exposed shores is dominated by the kelp Laminaria digitata (Ldig; Ldig.LdigBo), while the kelp Laminaria saccharina may co-dominate on sheltered shores (Lsac.Ldig; Lsac.Ft). Low abundance of these kelp may also occur in this biotope.

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 2 Occasional 41-60 %
Dynamena pumila 2 Occasional 41-60 %
Actinia equina 1 Occasional 41-60 %
Pomatoceros triqueter 2 Occasional 41-60 %
Spirorbidae 3 Common 41-60 %
Semibalanus balanoides 4 Frequent 61-80 %
Porcellana platycheles 1 Frequent 41-60 %
Carcinus maenas 2 Occasional 41-60 %
Gibbula cineraria 4 Occasional 61-80 %
Patella vulgata 7 Frequent 81-100 %
Littorina littorea 2 Frequent 41-60 %
Nucella lapillus 3 Occasional 61-80 %
Palmaria palmata 1 Frequent 41-60 %
Corallinaceae 5 Frequent 61-80 %
Corallina officinalis 2 Occasional 41-60 %
Chondrus crispus 3 Occasional 41-60 %
Mastocarpus stellatus 6 Frequent 61-80 %
Lomentaria articulata 2 Occasional 41-60 %
Osmundea pinnatifida 2 Frequent 41-60 %
Fucus serratus 20 Abundant 81-100 %
Enteromorpha intestinalis 3 Occasional 41-60 %
Ulva lactuca 2 Occasional 41-60 %

Similar biotopes

LR.MLR.BF.Fser.R
Occurs on bedrock rather than boulders. The species diversity and abundance of red seaweeds is higher, whilst the faunal component is less diverse due to the lack of micro-habitats. Mobile species such as the crabs Porcellana platycheles and Cancer pagurus and the starfish Asterias rubens are usually not present.

LR.LLR.F.Fserr.FS
Occurs on bedrock rather than boulders. Has a lower species richness and the abundance of many species are lower. Mobile species such as the crabs Porcellana platycheles and Cancer pagurus and the starfish Asterias rubens are usually not present.

LR.HLR.FT.FserT
Occurs on bedrock and boulders in very sheltered conditions. It also has a very high species diversity and sponges such as Halichondria panicea and Hymeniacidon perleve and bryozoans such as Electra pilosa or Alcyonidium gelatinosum are characteristic for this tide-swept biotope.

LR.LLR.FVS.FserVS
Occurs on variable salinity lower eulittoral bedrock and boulders. The individual M. edulis is large and the barnacle Elminius modestus can be present in high numbers. Sponges such as Halichondria panicea and red seaweeds such as Lomentaria articulata or Chondrus crispus are not present.

Biotope history

Classification Habitat code
6.95 LRK.FSE.BO
96.7 MLR.Fser.Bo
97.05 MLR.Fser.Fser.Bo

Photos

LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders, Sula Skerry, Ullinish, Loch Bracadale, Skye. David Connor © JNCC
LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders, Sula Skerry, Ullinish, Loch Bracadale, Skye. David Connor © JNCC
LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders, Broadstones, Farnes. Sarah Fowler © JNCC
LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders, Broadstones, Farnes. Sarah Fowler © JNCC
LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders, Unspecified location. Keith Hiscock © JNCC
LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders, Unspecified location. Keith Hiscock © JNCC

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