Eutrophication is one of the largest threats to the Baltic Sea manifested by algal blooms, turbid waters, loss of submerged vegetation and hypoxic and anoxic conditions at the sea bottom in large areas.
A number of EU and regional efforts, like EU Water Framework Directive, EU Marine Strategy Framework Directive and for the Baltic marine environment the HELCOM Baltic Sea Action Plan, have been put in place to stop further deterioration of eutrophic European marine ecosystems.
In the process of implementing the environmental goals, focus has so far been on traditional measures, e.g. sewage treatment plants in relation to point sources and a wide range of terrestrial efforts in relation to diffuse run-off from agriculture, to reduce nutrient loading to the marine environment. Most of these measures have, however, restricted capacity for further reducing nutrient loads, and the costs of implementing them are increasing at the margin.