AA.I1S Baltic photic coarse sediment characterized by annual algae


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. Annual algae cover at least 10 %, while all other epibenthic biotic structures cover less than 10 %.

Physical environment       

Salinity range: all; Exposure range: moderate; Depth range: photic zone

Characteristic species        

Chorda filum, Halosiphon tomentosus

Geographic range               

Whole Baltic Sea

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