HELCOM RED LIST Biotope Expert Team
Baltic aphotic 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. Coverage of sessile macroscopic epifauna is ≥10%.
Salinity range: all; Exposure range: moderate to high; Depth range: aphotic zone
Mytilus spp, Hydrozoa, Amphibalanus improvisus
Mapping advise (habitat delineation, identification, similar types)
Aphotic zone areas with coarse sediment such as gravel. Sediment must contain less than 20 % of mud/silt/clay fraction (<63 µm), and at least 30 % of grain size 2–63 mm. Coverage of sessile macroscopic epifauna is ≥10%.
Diversity, abundance and biomass of fauna.
Whole Baltic Sea
Soft sediment covering the coarse sediment will decrease the quality.
HELCOM 1998: 2.4 Gravel bottoms
2.4.1 Aphotic zone
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
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