In 2008, the highest summer chlorophyll-a concentrations were observed in coastal areas and estuaries where nutrient concentrations are high, namely in the Gulf of Riga, the Gulf of Finland and along the coast of France and Belgium. Although nutrient concentrations in some European sea areas decreased from 1985 to 2008 (see Core Set Indicator 21), these changes were not clearly reflected in chlorophyll-a concentrations: of the 546 stations reported to the EEA the majority of the stations (89%) indicated no statistically significant change. Changes were detected mainly in Finnish, Dutch, Norwegian, Swedish and Italian coastal waters. At the Finnish and Swedish monitoring stations chlorophyll-a concentrations showed both decreasing and increasing trends, whereas in Italy, Netherlands and Norway concentrations were mainly decreasing. An analysis of changes based on satellite imagery show significantly increasing trends of ocean colour (equivalent to chl-a)along the Mediterranean coast, whereas trends are significantly decreasing in large parts of the central Mediterranean and Black Seas. It also shows significantly increasing trends in the Baltic Sea, but here the analysis is less certain.
Data and maps
Chlorophyll in transitional, coastal and marine waters
Decreasing nutrient concentrations were found in the North Sea and in the Baltic Sea. In the Mediterranean and Black Sea, the lack of temporally and spatially comprehensive time series does not allow an overall assessment. In 2008, the highest concentrations of oxidized nitrogen were found in the Gulf of Riga, and in Lithuanian, Swedish, German, Belgian, and Scottish coastal waters. Between 1985 and 2008, 12% of all the stations in the European seas reported to the EEA showed decreasing trends of oxidized nitrogen concentrations. These trends were more evident in the open Baltic Sea and in the Dutch and German coastal waters in the North Sea. In 2008, the highest orthophosphate concentrations were found at Finnish coastal stations in the Gulf of Finland, the Gulf of Riga, German, Belgian, French, and Scottish coastal waters. Between 1985 and 2008, 15% of all the stations in the European seas reported to the EEA showed a decrease in orthophosphate concentrations, mainly because of improved waste water treatment. This decrease was most evident in Norwegian, Lithuanian, Danish, Belgian and Dutch coastal water stations, and in the open waters of the North and Baltic Seas.
Data and maps
Nutrients in transitional, coastal and marine waters