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 bivalves dominates and is highest in the group that includes infaunal bivalves/polychaetes/crustaceans/echinoderms/insect larvae. Out of the infaunal bivalves, Ocean quahog (Arctica islandica) constitutes at least 50 % of the biomass.
is muddy sediment. Appears in low to moderate energy exposure classes.
abundance and biomass of fauna
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 Critically Endangered (CR) in the HELCOM Red List of Baltic Sea biotopes and habitats.
See the Biotope Information Sheet of AB.H3L3