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Marine Habitat Classification

Description of biotope or habitat type

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   Styela gelatinosa, Pseudamussium septemradiatum and solitary ascidians on sheltered deep circalittoral muddy sediment

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Very sheltered
Tidal streams Weak (>1 kn)
Substratum Mud with terrigenous debris
Zone Circalittoral
Depth Band 50-100 m
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 SS.SMu.OMu.StyPse <I>Styela gelatinosa</I>, <I>Pseudamussium septemradiatum</I> and solitary ascidians on sheltered deep circalittoral muddy sediment

  • 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'
  • Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat

Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.


This biotope is known only from deep water in Loch Goil (Clyde sealochs) in fine mud at 65 m with terrigenous debris. Large numbers of solitary ascidians, including Styela gelatinosa, Ascidia conchilega, Corella parallelogramma and Ascidiella spp., are characteristic of this biotope together with the bivalve Pseudamussium septemradiatum. Terebellid worms, the bivalve Abra alba and the polychaete Glycera tridactyla may also occur. It is possibly an ice age relict biotope.


No situation data available.

Temporal variation

No temporal data available.

Characterising species

Taxon Typical abundance - SACFOR scale % of core records where taxon was recorded
Glycera tridactyla 81-100 %
Terebellidae Frequent 81-100 %
Pseudamussium septemradiatum Common 81-100 %
Abra alba Occasional 81-100 %
Paracucumaria hyndmani Rare 81-100 %
Corella parallelogramma Frequent 81-100 %
Ascidiella aspersa Frequent 81-100 %
Ascidiella scabra Abundant 81-100 %
Styela gelatinosa Frequent 81-100 %

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code
97.06 COS.Sty

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