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Marine Habitat Classification

Description of biotope or habitat type

To understand more about what this page is describing, see How to use the classification. See also How to cite.

   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

Biotope origin

Derived using data from Various
Faunal group Epifauna

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, sea lochs and voes but should only be described as SS.SMp.KSwSS.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
Tubificoides benedii 45 Abundant 81-100%
Kurtiella bidentata 19 Abundant 81-100%
Trailliella intricata 16 Common 61-80%
Bonnemaisonia hamifera 9 41-60%
Ascidiella aspersa 6 Rare 41-60%
Asterias rubens 6 Occasional 41-60%
Saccharina latissima 6 Occasional 41-60%
Mediomastus fragilis 6 Common 81-100%
Capitella capitata 5 Common 81-100%
Chorda filum 5 Rare 41-60%
Pagurus bernhardus 5 Occasional 41-60%
Pomatoschistus minutus 5 Rare 41-60%
Gibbula magus 4 41-60%
Liocarcinus depurator 4 Occasional 41-60%
Ophiura albida 4 41-60%
Phyllophora crispa 4 Rare 41-60%
Carcinus maenas 3 Occasional 41-60%
Monocorophium acherusicum 3 81-100%
Mya arenaria 3 81-100%
Mytilus edulis 3 81-100%
Protodorvillea kefersteini 3 81-100%
Rhodothamniella floridula 2 21-40%
Arenicola marina 1 Occasional 21-40%
Cerianthus lloydii 1 Occasional 21-40%

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code Habitat name
2015 (15.03) SS.SMp.KSwSS.Tra Mats of Trailliella on infralittoral muddy gravel
2004 (04.05) SS.SMp.KSwSS.Tra Mats of Trailliella on infralittoral muddy gravel
1997 (97.06) SS.IMX.KSwMx.Tra Mats of Trailliella on infralittoral muddy gravel

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