AA.M1B4 Baltic photic mixed substrate dominated by Charales


HELCOM RED LIST Biotope Expert Team

Textual description 

Baltic bottoms in the photic zone with more than 10 %, but less than 90 % coverage of both hard and soft substrata. Submerged rooted plants cover least 10 % of the seabed and more than other perennial attached erect groups. Out of the submerged rooted plants, Charales constitute at least 50 % of the biovolume.

Physical environment       

Salinity range: <6 psu; Exposure range: low; Depth range: photic zone from about 0.2 to 7 meters.

Characteristic species        

Chara aspera, Chara tomentosa, Tolypella nidifica, Chara horrida, Chara baltica


Whole Baltic Sea



Correspondence with other classification systems               

HELCOM 1998:

2.8 Mixed sediment bottoms

2.8.2 Sublittoral photic zone 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.M1B4