AB.J3L Baltic aphotic sand characterized by infaunal bivalves


HELCOM RED LIST Biotope Expert Team

Textual description            

Balticaphotic bottoms with at least 90 % coverage of sand. Sand has less than 20 % of mud/silt/clay fraction (<63 µm), and the proportion of sand (grain size 0.063–2 mm) exceeds 70% of the combined gravel and sand fraction. Sessile/semi-sessile epibenthic macrofauna is not present. Biomass of infaunal bivalves dominates and is the highest in the group that includes infaunal bivalves/polychaetes/crustaceans/insectlarvae.

Physical environment       

Substrate is sand. Depth below approximately 30 m. Appears in high energy exposure areas.

Characteristic species        

Macoma balthica Arctica islandica,Cerastoderma spp., Mya arenaria, Astarte borealis, Macoma calcarea, Mya truncata, Astarte spp., Spisula spp, Chamelea gallina

Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Whole Baltic Sea

Correspondence with other classification systems               

HELCOM 1998:
2.5Sandy bottoms

2.5.1Aphotic zone

EUNIS 2012:

A5 Sublittoral sediment

A5.2 Sublittoral sand

A5.27 Deep circalittoral sand

A5.273 Baltic sandy bottoms of the aphotic zone