AA.H1Q1 Baltic muddy sediment dominated by stable aggregations of unattached Fucus spp. (typical form)


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 µm). No perennial attached erect group has a coverage ≥ 10%. Stable aggregations of unattached perennial vegetation cover at least 10 % of the seabed. Out of the unattached perennial vegetation Fucus spp.(typical form) constitutes at least 50 % of the biovolume.

Physical environment       

Salinity range: >4.5 psu; Exposure range: low to moderately high; Depth range: photic zone from about 2 to 5 meters and deeper in clear waters.

Characteristic species        

Fucus vesiculosus(typical form), F. radicans

Quality descriptors             

Density of unattached Fucus spp. (normal form)

Geographic range               

Whole Baltic Sea

Anthropogenic threats     


Correspondence with other classification systems               

HELCOM 1998:
22.7 Muddy bottoms

2.7.2 Sublittoral photic zone Dominated by macrophyte vegetation

EUNIS 2012:

A5 Sublittoral sediment

A5.5 Sublittoral macrophyte-dominated sediment