AB.J4 Baltic aphotic sand characterized by no macroscopic biotic structures


HELCOM RED LIST Biotope Expert Team

Textual description            

Baltic bottoms in the aphotic zone 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. No macro- epi- or infauna.

Physical environment       

Salinity range: all; Exposure range: all; Depth range: below photic zone ‑ more common in deeper areas.

Characteristic species        

Oligochaeta, Ostracoda, Nematoda, Copepoda

Mapping advise (habitat delineation, identification, similar types)             

Sandy bottoms in the aphotic zone with less than 20 % of mud/silt/clay fraction (<63 µm), and more than 70 % of sand (grain size 0.063–2 mm ).No macro- epi- or infauna.

Geographic range               

Whole Baltic Sea

Anthropogenic threats     

Sand excavation, silting caused by eutrophication, dredging spoil deposition etc.

Correspondence with other classification systems               

HELCOM 1998:

2.5 Sandy bottoms

2.5.1 Aphotic zone


EUNIS 2012:

A5 Sublittoral sediment

A5.2 Sublittoral sand

A5.27 Deep circalittoral sand

A5.273 Baltic sandy bottoms of the aphotic zone