AA.H1Q3 Baltic muddy sediment dominated by stable aggregations of unattached Furcellaria lumbricalis


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  Furcellaria lumbricalis 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        

Furcellaria lumbricalis

Quality descriptors             

Lower limit of Furcellaria belt, amount of epiphytic algae, density of Furcellaria

Geographic range               

Baltic Sea up to the Quark in the north and central Gulf of Finland in the east

Anthropogenic threats     


Correspondence with other classification systems               

HELCOM 1998:
2.7 Muddy bottoms
2.7.2 Sublittoral photic zone Dominated by macrophyte vegetation

EUNIS 2012:
A5 Sublittoral sediment
A5.5 Sublittoral macrophyte-dominated sediment