AB.I3N3 Baltic aphotic coarse sediment dominated by sand digger shrimp (Bathyporeia pilosa)


HELCOM RED LIST Biotope Expert Team

Textual description 

Baltic aphotic zone bottoms with at least 90 % coverage of coarse sediment. Coarse sediment has less than 20 % of mud/silt/clay fraction (<63 µm), and the proportion of gravel and pebbles (grain size 2–63 mm) exceeds 30% of the combined gravel and sand fraction .Biomass of infaunal crustaceans dominates and is highest in the group that includes infaunal bivalves/polychaetes/crustaceans/echinoderms/insect larvae. Out of the infaunal crustaceans, Bathyporeia pilosa constitutes at least 50 % of the biomass.

Physical environment       

Substrate is muddy sediment. Appears in moderate to high energy exposure areas.

Characteristic species        

Bathyporeia pilosa

Quality descriptors

Diversity, abundance and biomass of fauna

Correspondence with other classification systems               

HELCOM 1998:

2.4 Gravel bottoms

2.4.1 Aphotic zone

EUNIS 2012:

A5 Sublittoral sediment

A5.1 Sublittoral coarse sediment

A5.11 Infralittoral coarse sediment in low or reduced salinity

A5.114 : Baltic gravel bottoms of the aphotic zone