AA.H1B2 Baltic photic muddy 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 muddy sediment. The sediment must contain at least 20 % of mud, silt or clay (grain size less than 63 µm). 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. 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 maritime, Zostera noltii

Quality descriptors             

Lower limit of vegetation, amount of epiphytic algae

Geographic range               

Whole Baltic Sea

Anthropogenic threats     


Correspondence with other classification systems               

HELCOM 1998:

2.7 Muddy bottoms

2.7.2 Sublittoral photic zone 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

A5.5343 [Ruppia maritima] in reduced salinity infralittoral muddy sand