AB.I1E Baltic aphotic coarse sediment characterized by epibenthic bivalves


HELCOM RED LIST Biotope Expert Team

Textual description            

Balticaphotic bottoms 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 . Sessile/semi-sessile epibenthic bivalves cover at least 10 % of the seabed.

Physical environment       

Substrate is coarse sediment. Depth below approximately 30 m. Appears in high energy exposure areas.

Characteristic species        

Mytilus spp.

Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Whole Baltic Sea

Correspondence with other classification systems               

HELCOM 1998:
2.4Gravel bottoms

2.4.1Aphotic zone

EUNIS 2012:

A5 Sublittoral sediment

A5.1 Sublittoral coarse sediment

A5.11 Infralittoral coarse sediment in low or reduced salinity

A5.114 : Baltic gravel bottoms of the aphotic zone