Eutrophication (nutrient enrichment and subsequent processes) and its adverse ecosystem effects have been discussed as main issues over the last 20 years in international conferences and conventions for the protection of the marine environment such as the North Sea Conferences and the 1992 OSPAR Convention (OSPAR; which combined and updated the 1972 Oslo Convention on dumping waste at the sea and the 1974 Paris Convention on land-based sources of marine pollution). OSPAR committed itself to reduce phosphorus and nitrogen inputs (in the order of 50% compared with 1985) into the marine areas and 'to combat eutrophication to achieve, by the year 2010, a healthy marine environment where eutrophication does not occur'. Within OSPAR, the Comprehensive Procedure (COMPP) has been developed and used to assess the eutrophication status of the OSPAR maritime area in an harmonised way. This is based on classification in terms of the following types of areas Non-Problem Areas (no effects), Potential Problem Areas (not enough data to assess effects) and Problem Areas (effects due to elevated nutrients and/or due to transboundary transport from adjacent areas). The COMPP consists of a set of harmonised assessment criteria with their area-specific assessment levels and an integrated area classification approach. The criteria cover all aspects of nutrient enrichment (nutrient inputs, concentrations and ratios) as well as possible direct effects (e.g. increased levels of nuisance and/or toxic phytoplankton species, shifts and/or losses of submerged aquatic vegetation) and indirect effects (e.g. oxygen deficiency, changes and/or death of benthos, death of fish, algal toxins). The COMPP also includes supporting environmental factors. It takes account of synergies and harmonisation with the EC Water Framework Directive, and has formed a major

Analyses of long-term trends in physical, chemical, and biological parameters at selected locations along the residual current represent one of the objectives of the North-West European Shelf Programme (NOWESP). Within this framework, trends in chlorophyll concentrations at two of these localities, the Irish Sea and the Dutch coastal zone, were analysed. The results show an increase in the Irish Sea from the end of the 1960s onwards. Chlorophyll concentrations increased from the early 1980s at two stations in the Dutch coastal zone (Marsdiep and 6 km offshore of Goeree), followed by a decrease during the end of the 1980s and 1990s to values comparable with those of the 1970s. In both areas, the increase in chlorophyll is almost exclusively due to higher summer values. Estimates of gross annual primary production calculated from the relation between chlorophyll and primary production measurements indicate a 50 to 100% increase in the Irish Sea over the last three decades. Estimated mean annual production between 1976 and 1992 at Goeree 6 was 375 gC m 2 . Marsdiep estimates are influenced by an increase of suspended particulate matter (SPM) during the 1980s followed by a marked reduction during the past 5 years. These changes in SPM may mask effects of changes in nutrient input.1996 International Council for the Exploration of the Sea

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