AB.M1G Baltic aphotic mixed substrate characterized by epibenthic cnidarians


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 cnidarians 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        

hydroids, sea anemones, corals

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