AA.H3L6 Baltic photic muddy sediment dominated by Unionidae

Author                                     

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). Biomass of infaunal bivalves dominates and is highest in the group that includes infaunal bivalves/polychaetes/crustaceans/echinoderms/insect larvae. Out of the infaunal bivalves  Unionidae constitutes at least 50 % of the biomass.

Physical environment       

Substrate is muddy sediment. Appears in low to moderate energy exposure classes. Salinity is low (below 2)

Characteristic species        

Unionidae

Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Freshwater outlets and coastal lagoons

Anthropogenic threats     

Eutrophication

Correspondence with other classification systems               

HELCOM 1998:

2.7 Muddy bottoms

2.7.2 Sublittoral photic zone

2.7.2.1 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

http://eunis.eea.europa.eu/habitats/2585


 Related information

This biotope has been listed as Near Threatened (NT) in the HELCOM Red List of Baltic Sea biotopes and habitats.

See the Biotope Information Sheet of AA.H3L6

 Publications

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