HELCOM RED LIST Biotope Expert Team
Baltic aphotic zone bottoms with at least 90 % coverage of muddy sediment. The sediment must contain at least 20 % of mud, silt or clay (grain size less than 63 µm). Biomass of infaunal crustaceans dominates and is highest in the group that includes infaunal bivalves/polychaetes/crustaceans/echinoderms/insect larvae. Out of the infaunal crustaceans, Monoporeia affinis and/or Pontoporeia femorata constitutes at least 50% of the biomass.
is muddy sediment. Depth is typically from approximately 20 to 200 meters.
Appears in all wave exposure classes. Salinity below 10.
Monoporeia affinis, Pontoporeia femorata, Saduria entomon
abundance and biomass of fauna. Number of healthy eggs in pregnant females.
Eutrophication, chemical pollution
2.7 Muddy bottoms
2.7.1 Aphotic zone
A5 Sublittoral sediment
A5.3 Sublittoral mud
A5.37 Deep circalittoral mud
A5.378 Baltic muddy bottoms of the aphotic zone
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This biotope has been listed as Near Threatened (NT) in the HELCOM Red List of Baltic Sea biotopes and habitats.
See the Biotope Information Sheet of AB.H3N1