Oxygen debt is an applicable indicator in the Bornholm Basin, Western Gotland Basin, Eastern Gotland Basin, Northern Baltic Proper and Gulf of Finland. Good environmental status (GES) has not been achieved in any of these sub-basins.
Oxygen debt below the halocline has increased both in the Baltic Proper and the Bornholm Basin since the early 1900's. The increase has been strong in the Baltic Proper, where the level has increased approximately 25% since the level observed under 1900-1920.
The confidence of the presented chlorophyll-a status estimate is high in all the sub-basins where the indicator was applied.
Average oxygen debt below halocline. (Open dynamic map viewer in new tab)
Organic matter decomposition to bottom waters increases along with increasing eutrophication. This leads to increasing oxygen consumption and subsequent decrease in bottom oxygen concentration. This core indicator focuses on one important aspect of the complex phenomenon, but does not alone assess the eutrophication status.
BSAP segment and objective
A Baltic Sea unaffected by eutrophication
MSFD descriptor and criteria
5.3. Indirect effects of nutrient enrichment
Other relevant legislation
Water Framework Directive
Pyhälä M, Fleming-Lehtinen V, Laamanen M, Łysiak-Pastuszak E, Carstens M, Leppänen J-M, Leujak W, Nausch G, Carstensen, J. 2014. Oxygen debt - HELCOM Core Indicator Report. Online. [Date Viewed], http://www.helcom.fi/baltic-sea-trends/indicators/oxygen/