What is eutrophication?
Eutrophication is the enrichment of nutrients in an ecosystem. Excessive amounts of nutrients encourage the growth of algae and other aquatic plants, which in turn leads to a multitude of negative effects such as extensive growth of algae (algae blooms) and oxygen depletion in the sea.
Excessive nutrient runoff from human activities, like agriculture, is contributing to the severe disruption of the Baltic Sea’s marine ecosystem, to the detriment of marine life and human health. We are working to address the problem by promoting policy reform and more sustainable farming and land management practices.
Eutrophication in the Baltic Sea
According to the second HELCOM assessment on the ‘State of the Baltic Sea,’ although nutrient inputs to the Baltic Sea have decreased, over 97% of the Baltic Sea area is still affected by eutrophication. It is unlikely that the nutrient inputs to the Baltic Sea will be reduced to reach the maximum allowable level in all subbasins by the deadline of 2021.
The good news is that many of the worst point sources of pollution have been addressed and significant gains have been made, including by improving wastewater treatment facilities and addressing industry runoff. The share of the total nutrient load contributed by these sectors has decreased substantially.
However, agricultural runoff from around the Baltic Sea has been more challenging to address due to the diffuse nature of the nutrient loading. The main pathways for nutrients are the five main rivers – the Neva, Nemunas, Daugava, Vistula and Oder. The expected development of agriculture around the region will worsen conditions if reductions in nutrient inputs to the Baltic Sea are not implemented. Another problem is the fact that much of the phosphorus already released to the Baltic Sea is now stored as an environmental liability in the sediments of the deeper parts of the basin. Anoxic (oxygen-free)conditions enhance the release of phosphorus from the sediment – so-called “internal loading” – and that, in turn, encourages algal blooms which, as they die, sink to the bottom and consume oxygen during the decomposition process.
The solution lies in agricultural policy and practice
A major solution to the problem of eutrophication lies in addressing land-based measures through policy reform, and the promotion of more sustainable farming and land management practices.