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Marine Habitat Classification


Description of biotope or habitat type

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   Ascophyllum nodosum on very sheltered mid eulittoral rock


Habitat (physical) description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams
Substratum Bedrock; stable boulders
Zone Eulittoral - mid
Depth Band
Other Features

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.LLR.F.Asc <I>Ascophyllum nodosum</I> on very sheltered mid eulittoral rock

  • 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

Sheltered to extremely sheltered mid eulittoral rock with the wrack Ascophyllum nodosum. The red seaweed Polysiphonia lanosa is often found growing as an epiphyte on the A. nodosum fronds while disturbed areas among the A. nodosum is colonised by the wrack Fucus vesiculosus and the green seaweed Enteromorpha intestinalis.e barnacle Semibalanus balanoides, the limpet Patella vulgata and Littorina littorea can all be found on the bedrock underneath the A. nodosum canopy along with coralline crusts. The whelk Nucella lapillus can be found preying on the barnacles and limpets. Three variants of this biotope are described. These are: full salinity (Asc.FS), mixed substrata (Asc.X) and the loose lying growth form A. nodosum ecad mackaii found on very sheltered shores (Asc.mac). To other biotopes has been identified as well tide-swept (AscT) and variabel salinity (AscVS).

Situation

This biotope is usually found between the wrack Fucus spiralis (Fspi) and F. serratus dominated biotopes (Fserr), although on some shores a narrow zone of F. vesiculosus (Fves) may occur immediately above the A. nodosum. With increasing wave exposure the A. nodosum canopy is replaced by F. vesiculosus (FvesB; Fves). Asc can occur on more exposed shores, where there is localised shelter.

Temporal variation

A. nodosum communities are generally very stable communities with individual plants reaching ages of more than 25 years on shores with little wave-action.

Characterising Species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Semibalanus balanoides 7 Frequent 61-80 %
Carcinus maenas 4 Occasional 41-60 %
Patella vulgata 4 Frequent 41-60 %
Littorina littorea 6 Occasional 41-60 %
Nucella lapillus 1 Occasional 21-40 %
Corallinaceae 2 Frequent 21-40 %
Polysiphonia lanosa 6 Frequent 61-80 %
Ascophyllum nodosum 33 Abundant 81-100 %
Fucus vesiculosus 10 Frequent 61-80 %
Ascophyllum nodosum mackaii 1 Rare 1-20 %
Enteromorpha intestinalis 2 Occasional 21-40 %

Similar biotopes

Not applicable or unknown.

Biotope history

Classification Habitat code
6.95 LRK.ASC

Photos

LR.LLR.F.Asc Ascophyllum nodosum on very sheltered mid eulittoral rock, E of causeway, Ault a chruinn, Loch Duich. David Connor © JNCC
LR.LLR.F.Asc Ascophyllum nodosum on very sheltered mid eulittoral rock, E of causeway, Ault a chruinn, Loch Duich. David Connor © JNCC
LR.LLR.F.Asc Ascophyllum nodosum on very sheltered mid eulittoral rock, Brada, Longstone, Farne Islands. Keith Hiscock © JNCC
LR.LLR.F.Asc Ascophyllum nodosum on very sheltered mid eulittoral rock, Brada, Longstone, Farne Islands. Keith Hiscock © JNCC

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