AA.I1B2 Baltic photic coarse sediment dominated by Zannichellia spp. and/or Ruppia spp. and/or Zostera noltii


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. Submerged rooted plants cover at least 10 % of the seabed and more than other perennial attached erect groups. Of the submerged rooted plants, Zannichellia spp. and/or Ruppia spp. and/or Zostera noltii constitute at least 50 % of the biovolume.

Physical environment       

Salinity range: low to moderate; Exposure range: low to moderate; Depth range: photic zone from about 0.1 to 4 meters.

Characteristic species        

Zannichellia palustris, Ruppia maritima, Zostera noltii


Whole Baltic Sea, Zostera noltii occurs only in the Belt Sea and Kattegat area.

Anthropogenic threats   


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

A5.53 Sublittoral seagrass beds

A5.534 : [Ruppia] and [Zannichellia] communities