Kaiser, J. and Lutter, S. (1998). “Do we have the right strategies to combat eutrophication in the Wadden Sea? - A critical review of current policies”. Senckenbergiana Maritima 29 (1-6): 17-24

Occurrence of wide anoxic black areas in the East Frisian Wadden Sea at the beginning of the summer of 1996 has highlighted adverse effects of eutrophication once again and reminded of the persisting need for further reduction of nutrient inputs. The Wadden Sea as part of the North Sea is subject to mostly the same political and legal agreements. However, internationally accepted decisions are often overridden by national policy considering economic interests. Furthermore, the envisaged 50% reduction in nutrient inputs is merely a political figure: Based on indications from ecological models and dose-effect-relationships, one has to call for a reduction of nitrogen and phosphorus inputs by, e.g., 75 to 85% in order to achieve a reduction of anthropogenic algal biomass by 50%. Thus, further measures as agreed by the Intermediate North Sea Ministerial Meeting (IMM, 1993) and the 4th North Sea Conference (NSC, 1995) are insufficient if aiming at a 50% reduction only. Secondary eutrophication from sediments and soil retention delay perceptible effects for several years and result in a high patchiness of responses. Since 1993, OSPAR's nutrient work is paralysed by technical discussions on the definition of Balanced Fertilisation and the Strategy to Combat Eutrophication. No comprehensive strategy to combat eutrophication has been adopted yet. The unresolved issue of EU competence questions OSPAR's role in agriculture policy and other areas. An operational concept of balanced fertilisation must achieve a simultaneous reduction of nitrogen and phosphorus inputs in order to avoid changes in the N:P ratio disturbing the ecosystem. Measures implemented so far have proven ineffective to reduce nitrogen inputs by more than 30%. Reduction effects from point sources are exhausted in near future, but diffuse sources remain to be a problem. The emission sources within transport and vehicle traffic have only been addressed in terms of inventories, but have not yet been approached with reduction programmes and measures by OSPAR. Precautionary reductions at source are at least as important as comprehensive monitoring programmes which can only recall the need for action. They are ecologically and economically more favourable than prolonged cost- and time-consuming research into cause-effect-relationships. Restoration measures and coastal management can support, but in no means replace far-reaching preventive measures to combat eutrophication.