AA.H3L Baltic photic muddy sediment characterized by infaunal bivalves


HELCOM RED LIST Biotope Expert Team

Textual description            

Baltic photic 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 ┬Ám). No macrovegetation or epibenthic macrofauna. Biomass of infaunal bivalves dominates in the group infaunal bivalves/polychaetes/crustaceans/echinoderms/insect larvae.

Physical environment       

Substrate is muddy sediment.

Characteristic species        

Macoma balthica, Arctica islandica, Astarte spp.

Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Whole Baltic Sea

Anthropogenic threats     

Eutrophication, contaminants

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