AA.I3L11 Baltic photic coarse sediment dominated by multiple infaunal polychaete species including Ophelia spp.


HELCOM RED LIST Biotope Expert Team

Textual description            

Baltic photic 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 forbesi constitute ≥10 %of the infaunal macrocommunity biomass when disregarding the biomass of bivalves.

Physical environment       

Substrate is sand.

Characteristic species        

Ophelia spp, Tanaissus spp, Streptosyllis spp.us

Quality descriptors

Diversity, abundance and biomass of fauna.

Geographical RAnge

Kiel bight to Darss sill

Correspondence with other classification systems   

HELCOM 1998:

2.4 Gravel bottoms

2.4.2 Sublittoral photic zone Level bottoms with little or no macrophyte vegetation

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

A5.111 : Baltic level gravel bottoms of the infralittoral photic zone with little or no macrophyte vegetation


 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.I3L11