AA.I1D Baltic photic coarse sediment characterized by aquatic moss


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. Aquatic moss cover at least 10 % of the seabed and more than other perennial attached erect groups.

Physical environment       

Salinity range: <5 psu; Exposure range: all, more common in exposed areas; Depth range: photic zone usually from about 1 to 7 meters

Characteristic species       

Fontinalis spp.

Geographic range               

Bothnian Bay. to the northern Bothnian Sea, Eastern Gulf of Finland

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