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Marine Habitat Classification


Description of biotope or habitat type

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   Ascophyllum nodosum ecad mackaii beds on extremely sheltered mid eulittoral mixed substrata


Habitat (physical) 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
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.FVS.Ascmac <I>Ascophyllum nodosum</I> ecad <I>mackaii</I> beds on extremely sheltered mid eulittoral mixed substrata

  • 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

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.

Situation

Occurs in extremely sheltered conditions at the heads of Scottish sea lochs (but is also known from other sheltered areas).

Temporal variation

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.

Characterising Species

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 %
Gammaridae 7 Frequent 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

LR.LLR.F.Asc.X
Occurs in fully marine conditions and the non-attached growth form A. nodosum ecad mackaii is not present.

Biotope history

Classification Habitat code
6.95 LMXD.AMAC
97.06 SLR.AscX.mac

Photos

LR.LLR.FVS.Ascmac Ascophyllum nodosum ecad mackaii beds on extremely sheltered mid eulittoral mixed substrata, Carness, Loch Leven. Steve Bolt © JNCC
LR.LLR.FVS.Ascmac Ascophyllum nodosum ecad mackaii beds on extremely sheltered mid eulittoral mixed substrata, Carness, Loch Leven. Steve Bolt © JNCC
LR.LLR.FVS.Ascmac Ascophyllum nodosum ecad mackaii beds on extremely sheltered mid eulittoral mixed substrata, Obs, NW Scotland. Kate Northen © JNCC
LR.LLR.FVS.Ascmac Ascophyllum nodosum ecad mackaii beds on extremely sheltered mid eulittoral mixed substrata, Obs, NW Scotland. Kate Northen © JNCC
LR.LLR.FVS.Ascmac Ascophyllum nodosum ecad mackaii beds on extremely sheltered mid eulittoral mixed substrata, Salen Harbour, Loch Sunart. Rohan Holt © JNCC
LR.LLR.FVS.Ascmac Ascophyllum nodosum ecad mackaii beds on extremely sheltered mid eulittoral mixed substrata, Salen Harbour, Loch Sunart. Rohan Holt © JNCC

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