AA.I1Q3 Baltic photic coarse 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 coarse sediment. Coarse sediment has less than 20 % of mud/silt/clay fraction (<63 µm), and the proportion of gravel and pebbles (grain size 2–63 mm) exceeds 30% of the combined gravel and sand fraction . No perennial attached erect group has a coverage ≥ 10%. Stable aggregations of unattached perennial vegetation covers at least 10 %, out of which Furcellaria lumbricalis constitutes at least 50 % of the biovolume.

Physical environment       

Salinity range: >4.5 psu; Exposure range: sheltered to exposed; Depth range: photic zone from about 2 to 10 meters

Characteristic species        

Furcellaria lumbricalis

Geographical RAnge

Whole Baltic Sea, typical along the coast of the Baltic states


Decreased light penetration depth and increased sedimentation caused by eutrophication.

Correspondence with other classification systems               

HELCOM 1998:

2.4 Gravel bottoms

2.4.2 Sublittoral photic zone Level bottoms dominated by macrophyte vegetation

EUNIS 2012:

A5 Sublittoral sediment

A5.5 Sublittoral macrophyte-dominated sediment