Description of biotope or habitat type
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|
|Substratum||Bedrock; stable boulders|
|Zone||Eulittoral - mid|
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.
- 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.
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).
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.
A. nodosum communities are generally very stable communities with individual plants reaching ages of more than 25 years on shores with little wave-action.
|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 %|
|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 %|
Not applicable or unknown.