AB.M1E Baltic aphotic mixed substrate characterized by epibenthic bivalves


HELCOM RED LIST Biotope Expert Team

Textual description

Baltic aphotic bottoms with 10- 90 % coverage of hard (rock/boulders/stone) and 10-90 % soft substrata (e.g. muddy/coarse sediment/sand).  Sessile/semi-sessile epibenthic bivalves cover at least 10 % of the seabed and more than other perennial attached erect groups.

Physical environment

Substrate is soft or crystalline rock, boulders or stones mixed with mobile substrates such as sand or coarse substrate. Depth is typically from 20 to 100 meters.

Characteristic species

Mytilus spp.

Quality descriptors

Diversity, abundance and biomass of fauna.

Geographic range

Whole Baltic Sea

Anthropogenic threats


Correspondence with other classification systems

HELCOM 1998:

2.8 Mixed sediment bottoms

2.8.1 Aphotic zone

EUNIS 2012:

A5 Sublittoral sediment

A5.4 : Sublittoral mixed sediments

A5.41 : Sublittoral mixed sediment in low or reduced salinity

A5.412 : Baltic mixed sediment bottoms of the aphotic zone