AA.H3N2–Baltic photic muddy sediment dominated by mud shrimps (Corophiidae)


HELCOM RED LIST Biotope Expert Team

Textual description            

Baltic photic zone bottoms with at least 90 % coverage of muddy sediment. The sediment must contain at least 20 % of mud, silt or clay (grain size less than 63 µm). Biomass of infaunal crustaceans dominates and is highest in the group that includes infaunal bivalves/polychaetes/crustaceans/echinoderms/insect larvae. Out of the infaunal crustaceans Corophiidae constitutes at least 50% of the biomass.

Physical environment       

Substrate is muddy sediment. Depth is typically from 1 to 5 meters. Appears in low wave exposure classes.

Characteristic species        

Corophium volutator, Apocorophium lacustre

Quality descriptors             

Diversity, abundance and biomass of fauna.

Anthropogenic threats   


Correspondence with other classification systems               

HELCOM 1998:

2.7 Muddy bottoms

2.7.2 Sublittoral photic zone With little or no macrophyte vegetation

EUNIS 2012:

A5 Sublittoral sediment

A5.3 Sublittoral mud

A5.31 Sublittoral mud in low or reduced salinity

A5.311 Baltic brackish water sublittoral muddy biocenoses influenced by varying salinity