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Marine Habitat Classification

Description of biotope or habitat type

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   Mats of Trailliella on infralittoral muddy gravel

Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered, Extremely sheltered
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Muddy gravel; muddy sand
Zone Infralittoral
Depth Band 0-5 m, 5-10 m, 10-20 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.SMp.KSwSS.Tra Mats of <I>Trailliella</I> on infralittoral muddy gravel

  • 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.


Dense loose-lying beds of the 'Trailliella' phase of Bonnemaisonia hamifera may occur in extremely sheltered shallow muddy environments. Beds of this alga are often 10 cm thick but may reach 100 cm at some sites. Other loose-lying algae may also occur such as Audouinella floridula, Phyllophora crispa and species of Derbesia. Often the mud is gravelly or with some cobbles and may be black and anoxic close to the sediment surface. This biotope is widely distributed in lagoons, sealochs and voes but should only be described as SMP.Tra when a continuous mat is found. It is likely that the infaunal component of this biotope may be considerably modified by the overwhelming quantity of loose-lying algae.


No situation data available.

Temporal variation

No temporal data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Cerianthus lloydii 1 Occasional 21-40 %
Protodorvillea kefersteini 3 81-100 %
Capitella capitata 5 Common 81-100 %
Mediomastus fragilis 6 Common 81-100 %
Arenicola marina 1 Occasional 21-40 %
Tubificoides benedii 45 Abundant 81-100 %
Corophium acherusicum 3 81-100 %
Pagurus bernhardus 5 Occasional 41-60 %
Liocarcinus depurator 4 Occasional 41-60 %
Carcinus maenas 3 Occasional 41-60 %
Gibbula magus 4 41-60 %
Mytilus edulis 3 81-100 %
Mysella bidentata 19 Abundant 81-100 %
Mya arenaria 3 81-100 %
Asterias rubens 6 Occasional 41-60 %
Ophiura albida 4 41-60 %
Ascidiella aspersa 6 Rare 41-60 %
Pomatoschistus minutus 5 Rare 41-60 %
Bonnemaisonia hamifera 9 41-60 %
Rhodothamniella floridula 2 21-40 %
Phyllophora crispa 4 Rare 41-60 %
Trailliella intricata 16 Common 61-80 %
Chorda filum 5 Rare 41-60 %
Laminaria saccharina 6 Occasional 41-60 %

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code
97.06 IMX.Tra

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