Description of biotope or habitat type
Ascophyllum nodosum ecad mackaii beds on extremely sheltered mid eulittoral mixed substrata
Physical habitat description
|Salinity||Variable (18-35 ppt)|
|Wave exposure||Extremely sheltered|
|Tidal streams||Weak (>1 kn), Very weak (negligible)|
|Substratum||Pebbles and cobbles on mud and sand|
|Zone||Eulittoral - mid|
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- 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.
Extremely sheltered mid shore mixed substrata, usually subject to variable salinity due to freshwater runoff, which support beds of the non-attached growth form of the wrack Ascophyllum nodosum ecad mackaii. Cobbles and other hard substrata are often characterised by the normal form of A. nodosum with the red seaweed Polysiphonia lanosa growing as an epiphyte and other fucoids such as Fucus vesiculosus. The loose mats of A. nodosum ecad mackaii provide a cryptic and humid habitat for mobile species including gammarids, the crab Carcinus maenas and the winkles Littorina littorea, Littorina obtusata and Littorina saxatilis. The barnacle Semibalanus balanoides and the mussel Mytilus edulis are commonly attached to pebbles and cobbles on the sediment, while the infauna may contain the polychaetes Arenicola marina and Lanice conchilega. NB: This biotope is a BAP-habitat.
Occurs in extremely sheltered conditions at the heads of Scottish sea lochs (but is also known from other sheltered areas).
A. nodosum ecad mackaii develops initially from broken fragments of A. nodosum and can in sheltered conditions grow in unattached, often bladderless, wig-shaped masses in the mid to upper tide zone. Note: "Ecad" has no official status in International Code of Botanical Nomenclature, but the terminology has been applied to the free-living form of A. nodosum since the beginning of the 19th century. The term was first employed by Clements (1905) to denote a form which results from adaptation or a change in morphology due to a new habitat - phenotypic variation.
|Taxon||Relative importance of taxon for defining this community (%)||Typical abundance - SACFOR scale||% of core records where taxon was recorded|
|Semibalanus balanoides||5||Occasional||41-60 %|
|Carcinus maenas||9||Rare||61-80 %|
|Littorina obtusata/mariae||3||Frequent||41-60 %|
|Littorina littorea||10||Occasional||61-80 %|
|Littorina saxatilis||5||Occasional||41-60 %|
|Polysiphonia lanosa||2||21-40 %|
|Ascophyllum nodosum||10||Rare||61-80 %|
|Fucus vesiculosus||11||Occasional||61-80 %|
|Ascophyllum nodosum mackaii||24||Occasional||81-100 %|
Similar biotopes or habitat types
Classification history of this biotope or habitat type