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Marine Habitat Classification

Description of biotope or habitat type

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   Beggiatoa spp. on anoxic sublittoral mud

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 Mud
Zone Infralittoral
Depth Band 0-5 m, 5-10 m, 10-20 m
Other Features Anoxic

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.SMu.IFiMu.Beg <I>Beggiatoa</I> spp. on anoxic sublittoral mud

  • 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.


Sublittoral soft anoxic mud, often in areas with poor water exchange with the open sea, can have a conspicuous bacterial mat covering of Beggiatoa spp. The anoxia may be a result of natural conditions of poor water exchange in some sea lochs (and many Scandinavian fjords) or artificially under fish farm cages from nutrient enrichment. The fauna is normally impoverished at such sites, with few elements of the infaunal communities present in other muddy biotopes. Scavenging species such as Asterias rubens and Carcinus maenas are typically present where the habitat is not too anoxic along with occasional Arenicola marina but in extreme conditions of anoxia little survives other than the Beggiatoa. The polychaete Oxydromus flexuosus occurs in high densities at the interface between oxygenated and deoxygenated sediments (in Norwegian fjords).


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
Beggiatoa 75 81-100%
Carcinus maenas 18 41-60%
Polychaeta 2 1-20%
Asterias rubens 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.SMu.IFiMu.Beg Beggiatoa spp. on anoxic sublittoral mud
2004 (04.05) SS.SMu.IFiMu.Beg Beggiatoa spp. on anoxic sublittoral mud
1997 (97.06) SS.CMU.Beg Beggiatoa spp. on anoxic sublittoral mud

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