AB.B1E1 Baltic aphotic hard clay dominated by Mytilidae


HELCOM RED LIST Biotope Expert Team

Textual description 

Baltic aphotic bottoms at least 90 % coverage of hard clay. Epibenthic bivalves cover at least 10%of the seabed and more than other perennial attached erect groups. Out of the epibenthic bivalves, Mytilidae constitutes at least 50 % of the biomass.

Physical environment       

Substrate is hard clay. Occur at high energy exposure areas.

Characteristic species        

Mytilus spp., Modiolus modiolus

Correspondence with other classification systems               

HELCOM 1998:

2.3 Hard clay bottoms

2.3.1. Aphotic zone

EUNIS 2012:

OSPAR list of threathened biotopes:

Modiolus modiolus beds

- Habitat occurs in the OSPAR Region II (including Kattegat) and is listed threatened and/or declining in this region