Ocean Colour observations in support of European Marine Framework Directives

Marine and coastal environments host a great biodiversity and supply multiple services for human activities, such as food and jobs availability. However, these zones are also affected by anthropic pressure and are particularly vulnerable to climate change. In order to protect its marine ecosystems and foster a sustainable use of the marine resources, the European Union adopted the Marine Strategy Framework Directive in 2008. This directive tasked each Member State to define a strategy to reach a “Good Environmental Status” (GES). Among the descriptors used to monitor GES, the assessment of the eutrophication level is of particular importance as 46% of coastal waters suffer from eutrophication. Then, marine strategies comprise regular assessments of the marine environment to monitor impact of national programmes and measures to improve the state of marine waters.

To perform these assessments, in situ measurements may not be sufficient due to their relatively low frequence of sampling, and their limited spatial coverage. Nevertheless, the combination of in situ data with satellites observations meet the need for the assessment strategies. While in situ measurements provide crucial ground truth references, satellite observations offer a high frequence of revisit and allow to document large spatial area. The usefulness of the ocean colour parameters will be presented. Indeed, parameters derived from ocean colour supply a wide range of information on the state of the marine waters, notably the chlorophyll concentration and the sea water transparency.

The developed methodology and metrics to detect eutrophication event in the French coastal area in collaboration with the French Office of the Biodiversity (OFB) will also be presented.