|Marine Environment Challenge|
The aim of the Marine Environment Challenge is to produce gridded data layers showing seasonal averages of eutrophication for the past ten years and change in eutrophication over the past ten years for the complete North Sea study area. This will be carried out using existing data in order to assess whether the availability, consistency and resolution of the data are sufficient. The outcome of this challenge will be to inform the data adequacy report to provide a detailed assessment of the gaps and priorities of observation and data on eutrophication in the North Sea.
The data identification phase has been completed and all information is currently being pursued. The way the data will be processed to derive an assessment of the level eutrophication in the North Sea over a period of 10 years will largely depend on the data available. Assessments made by OSPAR are generally made based on direct sampling of the sea, but such datasets will have limited spatial and temporal coverage. The dataset which is likely to have sufficient spatial coverage to produce gridded maps of eutrophication is likely be surface chlorophyll-a concentrations derived from remote sensing. In that case, the literature will be reviewed to determine the most appropriate analytical method to relate chlorophyll concentrations to eutrophication. This will be linked to more comprehensive assessments (e.g. the OSPAR Comprehensive Procedure) for areas where sufficient spatial and temporal data are available from direct measurement sources to include other parameters such as nutrients.
The processing will also take into account the relationship between observed surface chlorophyll concentrations (and hence eutrophication) and aspects of the hydrodynamics and bathymetry of the North Sea. In particular, the areas of influence of specific estuarine inputs may be deducible from the spatial chlorophyll data and turbidity data from remote sensing, and the relationship between water depth (from bathymetry) and eutrophication.