AA.I3M Baltic photic coarse sediment characterized by infaunal polychaetes


HELCOM RED LIST Biotope Expert Team

Textual description            

Baltic photic 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. No macrovegetation or epibenthic macrofauna.  Biomass of infaunal polychaetes dominates in the group infaunal bivalves/polychaetes/crustaceans/echinoderms/insect.

Physical environment       

Substrate is coarse sediment. Appears in high energy exposure areas.

Characteristic species        

Ophelia spp.

Quality descriptors             

Diversity, abundance and biomass of fauna.

Geographic range               

Whole Baltic Sea

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