AB Baltic aphotic benthos


HELCOM RED LIST Biotope Expert Team

Textual description

The vertical zone below which the amount of light is not sufficient for photosynthesis.

Physical environment

Salinity range: All; Exposure range: Typically more exposed areas; Depth range: usually deeper than 15 meters.

Characteristic species


Mapping advise (habitat delineation, identification, similar types)

The area deeper than Secchi depth multiplied by 2.5. Due to temporal variation of water turbidity, the depth should represent a long-term growth season average. The absence of foliose vegetation can also be used with other indicators.

Quality descriptors

High abundance and diversity (“high” is dependent on Sea area) of macrozoobenthos indicates good environmental status.

Geographic range

Whole Baltic Sea

Anthropogenic threats

Oxygen depletion caused by increased organic sedimentation. Locally dredging and dumping of dredge spoil, poisonous effluents, bottom trawling.

Correspondence with other classification systems

HELCOM 1998:

2. Benthic marine biotopes

EUNIS 2012:

A Marine habitats