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See all EU institutions and bodiesKey messages: Eutrophication is still a large-scale problem in the Baltic, Black and Greater North Seas and some coastal areas of the Mediterranean. Nutrient levels declined significantly between 1980 and 2023 but eutrophication remains an important problem. Although progress has been made in reducing inputs of some nutrients, particularly nitrogen, further efforts are necessary, especially for phosphorus reduction.
Number of time series available showing increasing, decreasing or no trends in dissolved inorganic nitrogen and orthophosphate concentrations for each regional sea for two time periods; Pre 2000 (1980-1999) and Post 2000 (2000-2023)
Eutrophication in marine waters occurs when excessive nutrients, primarily nitrogen and phosphorus, enter the ecosystem. Many nutrient sources, such as agriculture runoff and wastewater discharge, result from human activities . This excessive availability of nitrogen and phosphorus accelerates the growth of microalgae. Algal blooms associated with eutrophication can produce toxins that harm or kill marine organisms and consume oxygen that is necessary for marine life.
Available time series show that nutrient levels (nitrogen and phosphorus) in Europe’s transitional, coastal and marine waters generally declined between 1980 and 2023. The main reason for the decline would be the abatement measures. Most time series (91–94 %) show no significant change, indicating that many areas are stable.
Decreases in dissolved inorganic nitrogen (DIN) are most evident in the Baltic and Greater North Seas, while declines in phosphorus are less widespread, with some areas – especially parts of the Baltic and Black Seas. Increases are likely to be caused by phosphorus release from oxygen-poor sediments. Because data are limited in many regions, clear trends for nitrogen or phosphorus cannot be identified in every regional sea.
Please consult the relevant indicators and signals below for a more comprehensive overview on the topic.
References and footnotes
- ↵EEA, 2019, ‘Nutrient enrichment and eutrophication in Europe’s seas’, EEA Report No 14/2019, European Environment Agency (https://www.eea.europa.eu/publications/nutrient-enrichment-and-eutrophication-in) accessed 13 May 2024.
- EU, 2008, Directive 2008/56/EC of the European Parliament and of the Council of 17 June 2008 establishing a framework for community action in the field of marine environmental policy (Marine Strategy Framework Directive, MSFD) (OJ L 164, 25.6.2008).↵