The Year 2006 An Eutrophication Status Report of the North Sea, Skagerrak Kattegat and the Baltic Sea. A demonstration Project.

Typ: Rapport
Serie: Oceanografi 91
Författare: Elin Almroth, Morten Skogen, Ian Sehested Hansen Tapani Stipa, Susa Niiranen


This is the third year joint status report for the North Sea, Skagerrak, Kattegat and the Baltic Sea area (Fig. 1) carried out by SMHI, IMR, DHI and FIMR as a part of the project BANSAI, supported by the Nordic Council of Ministers’ Sea and Air Group. The aim of the demonstration project is to integrate marine observations and eutrophication model simulations in an annual eutrophication assessment of the Baltic and the North seas. The present report is mainly based on model estimates of some of the indicators suggested by the OSPAR Common Procedure (c.f. Appendix) for the identification of the eutrophication status of the maritime area (OSPAR, 2005). This report serve as a basis for the on-going discussions about the ecological quality indicators included in the assessment, and the way to merge results from different models and observations for the assessment. Estimations of river discharges and model results are used to describe the degree of nutrient enrichment (Category I) defined by the riverine loadings of nitrogen and phosphorus, and winter surface concentrations and ratios of DIN and DIP. The direct effects of nutrient enrichment during the growing season (Category II) are described in terms of the mean and maximum chlorophyll-a concentrations and model estimations of primary production. The ratio between diatoms and flagellates is used as an indicator of region specific phytoplankton indicator species (Category II). The indirect effects of nutrient enrichment (Category III) are discussed in terms of oxygen depletion in bottom waters. Estimations of region specific background concentrations and threshold values are gathered from the literature (Helcom, 2006; OSPAR, 2005) and used for the model assessment. The four model systems used for the joint assessment (Fig. 2) cover different parts of the North Sea, Skagerrak, Kattegat and the Baltic Sea area. Detailed descriptions of the models may be found on the web-sites presented below the figure. In section 2 the key messages from this assessment will be presented. In section 3, each country gives a brief observations overview for 2006 and some references to other sources and reports that might be useful for the readers. The methods of the assessment are described in section 4. Statistical characteristics of model results and in-situ data are presented in section 5 and the model assessment of eutrophication status is done in section 6. Conclusions and comments to the assessment are presented in section 7.