AA.I1E1 Baltic photic coarse sediment dominated by Mytilidae


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 . Epibenthic bivalves cover more than 10 % of the seabed, and more than other perennial attached erect groups. Out of the epibenthic bivalves Mytilidae constitute at least 50 % of the biomass.

Physical environment       

Substrate is coarse sediment. Appears in high energy exposure areas. Salinity >5 psu.

Characteristic species        

Mytilus spp., Hediste diversicolor

Quality descriptors

Diversity, abundance and biomass of fauna.

Correspondence with other classification systems               

HELCOM 1998:

2.4 Gravel bottoms

2.4.2 Sublittoral photic zone Level bottoms with little or no macrophyte


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