AB.I3L11 Baltic aphotic coarse sediment dominated by multiple infaunal polychaete species including Ophelia spp. and Travisia forbesii


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 bivalves dominates and is highest in the group that includes infaunal bivalves/polychaetes/crustaceans/echinoderms/insect larvae. Ophelia spp. and Travisia forbesii constitute ≥10 % of the macroinfaunal biomass when disregarding the biomass of bivalves.

Characteristic species        

Ophelia spp , Travisia forbesii , Tanaissus spp., Streptosyllis spp.

Quality descriptors

Diversity, abundance and biomass of fauna


Kiel bight to Darss sill

Correspondence with other classification systems               

HELCOM 1998:

2.4 Gravel bottoms

2.4.1 Aphotic zone

HELCOM 2007:

Gravel bottoms with Ophelia species

- habitat under threat and/or in decline in all areas of occurrence: Bay of Mecklenburg, Kiel Bay, Little Belt, Great Belt,  The Sound, Kattegat

 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


 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 AB.I3L11