AA.I1C4 Baltic photic coarse sediment dominated by kelp


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 . Perennial attached algae cover at least 10 % of the seabed and more than other perennial attached erect groups. Out of the perennial attached algae kelp constitute at least 50 % to the biovolume.

Physical environment       

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

Characteristic species        

Saccharina latissima


Belt Sea, the Sound, (Kattegat)

Anthropogenic threats   

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

A5.52 Kelp and seaweed communities on sublittoral sediment