AA.J1B4 Baltic photic sand dominated by Charales


HELCOM RED LIST Biotope Expert Team

Textual description            

Baltic bottoms in the photic zone with at least 90 % coverage of sand. Sand has less than 20 % of mud/silt/clay fraction (<63 µm), and the proportion of sand (grain size 0.063–2 mm) exceeds 70% of the combined gravel and sand fraction.  Submerged rooted plants, including plants with rhizoids (i.e. Charales) cover at least 10 % of the seabed, and more than other perennial attached erect groups. Out of the submerged rooted plants, Charales constitutes at least 50 % of the biovolume.

Physical environment       

Salinity range: <6 psu; Exposure range: sheltered to moderate; Depth range: from 0.2 to about 7 meters

Characteristic species        

Chara aspera, Tolypella nidifica, Chara baltica


Whole Baltic Sea

Anthropogenic threats

Decreased light penetration depth and increased sedimentation caused by eutrophication

Correspondence with other classification systems               

HELCOM 1998:

2.5 Sandy bottoms

2.5.2 Sublittoral photic zone Level bottoms dominated by macrophyte vegetation

EUNIS 2012:

A5 Sublittoral sediment

A5.5 Sublittoral macrophyte-dominated sediment


 related information

This biotope has been listed as Near Threatened (NT) in the HELCOM Red List of Baltic Sea biotopes and habitats.

See the Biotope Information Sheet of AA.J1B4