AA.H4 Baltic photic muddy sediment characterized by no macroscopic biotic structures


HELCOM RED LIST Biotope Expert Team

Textual description

Baltic bottoms in the photic 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 ┬Ám). No macrovegetation, no macro- epi- or infauna

Physical environment

Salinity range: all; Exposure range: sheltered; Depth range: the lowest part of the photic zone

Mapping advise (habitat delineation, identification, similar types)

Photic zone areas with muddy sediment, such as soft clay, silt or mud. This includes mixed sediments where clay and/or mud are mixed with sand or gravel. No macrovegetation, no macro- epi- or infauna

Geographic range

Whole Baltic Sea

Anthropogenic threats


Correspondence with other classification systems

HELCOM 1998:
2.7 Muddy bottoms

2.7.2 Sublittoral photic zone With little or no macrophyte vegetation

EUNIS 2012:

A5 Sublittoral sediment

A5.3 Sublittoral mud

A5.31 Sublittoral mud in low or reduced salinity

A5.311 Baltic brackish water sublittoral muddy biocenoses influenced by varying salinity

A5.3111 Baltic muds of the infralittoral photic zone with little or no macrophyte vegetation