Paula Schönach, 22.12.2010

Oxygen deficiency in the Baltic still severe

Recent measurements at the deep waters of the Baltic Proper reveal that the oxygen situation is still extremely severe, as it has been over the last decade. The Swedish Meteorological and Hydrological Institute published recently the newest data of oxygen in the deep waters of the Baltic Proper. The area with severe lack of oxygen (i.e. less than 2 ml/l) has increased from the already worrisome numbers from earlier this decade, reaching now a total of 45 % of the bottom area and some 30 % of the volume of the Baltic Proper. This is more than ever during the measurement history reaching back to 1960.

Completely oxygen free conditions set free toxic hydrogen sulphide. During recent expeditions hydrogen sulphide was found in new areas and shallower waters than ever before. Hydrogen sulphide is poisonous to all higher organisms, and high levels lead to dead zones on the sea floor. Hypoxia can occur as a natural phenomenon but the recent trends indicate also strong human influence through nutrient discharges and eutrophication.

Since protection measures influence the water quality and bottom conditions only after a considerable time span, scientists have a great responsibility in mediating their findings to the public and the decision-makers. The numerous on-going programmes and action plans to combat eutrophication at national and international level highlight the fact that Baltic Sea protection is seriously recognised on the political agenda. Still more public awareness in all riparian countries is needed to put the necessary pressure on the implementation process of the current ambitious plans for Baltic Sea protection. This kind of news point out, that the turn into better has not been reached yet.

Read more about the SMHI:s oxygen survey 2010 from here.