AB.A2T Baltic aphotic rock and boulders characterized by sparse epibenthic macrocommunity.


HELCOM RED LIST Biotope Expert Team

Textual description            

Baltic bottoms in the aphotic zone with at least 90 % coverage of rock, boulders or stones of more than 63 mm in diameter. Sessile/semi-sessile epibenthic fauna is present but covers less than 10 % of the seabed.

Physical environment       

Substrate is rock and boulders. Depth is typically from approximately 20 meters and deeper.

Characteristic species        

Mytilus spp. Bryozoa, Balanidae, Bryozoa, Porifera, Hydrozoa

Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Whole Baltic Sea

Anthropogenic threats     


Correspondence with other classification systems               

HELCOM 1998:

2.1 Rocky bottoms

2.1.1 Aphotic zone

2.2 Stony bottoms

2.2.1 Aphotic zone