AB.H Baltic aphotic muddy sediment


HELCOM RED LIST Biotope Expert Team

Textual description

Baltic bottoms in the aphotic zone 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).

Physical environment

Salinity range: All; Exposure range: All; Depth range: Below photic zone ‑ more common in deeper areas.

Characteristic species

Macoma balthica, Marenzelleria spp.

Geographic range

Whole Baltic Sea

Correspondence with other classification systems

HELCOM 1998:

2.7 Muddy bottoms

2.7.1 Aphotic zone


EUNIS 2012:

A5 Sublittoral sediment

A5.3 Sublittoral mud

A5.37 Deep circalittoral mud

A5.378 Baltic muddy bottoms of the aphotic zone