AA.I1 Baltic photic coarse sediment characterized by macroscopic epibenthic biotic structures


HELCOM RED LIST Biotope Expert Team

Textual description

Baltic bottoms in the photic zone 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 macroscopic vegetation or sessile macroscopic epifauna is ≥10 %.

Physical environment

Salinity range: all; Exposure range: moderate; Depth range: photic zone

Characteristic species

Zostera marina, Zannichellia spp., Tolypella nidifica, Fucus spp., Furcellaria lumbricalis, Mytilus spp., Hediste diversicolor

Mapping advise (habitat delineation, identification, similar types)

Photic zone areas with coarse sediment such as gravel. Sediment must contain less than 20 % of silt, clay or mud, and at least 30 % of grain size 2–63 mm. Coverage of vegetation is at least 10 %.

Geographic range

Whole Baltic Sea

Anthropogenic threats

Decreased light penetration depth and increased sedimentation caused by eutrophication

Correspondence with other classification systems

HELCOM 1998:

2.4 Gravel bottoms

2.4.2 Sublittoral photic zone Level bottoms dominated by macrophyte vegetation

EUNIS 2012:

A5 Sublittoral sediment

A5.1 Sublittoral coarse sediment

A5.11 Infralittoral coarse sediment in low or reduced salinity