AA.H1K1 Baltic photic muddy sediment dominated by tube-building polychaetes


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 ┬Ám). Epibenthic polychaetes cover at least 10% of the seabed and more than other perennial attached erect groups. Out of the epibenthic polychaetes tube-building polychaetes constitute at least 50 % of the biomass.

Physical environment       

Substrate is muddy sediment. Appears in low to moderate energy exposure classes.

Characteristic species        

Several species from the taxa Maldanidae and Terebellida.

Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Western Baltic Sea, including the Sound and Kattegat.

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