Is phytoplankton a useful indicator for Wadden Sea eutrophication?

Justus van Beusekom
Alfred Wegener Institute for Polar and Marine Research
Wadden Sea Station Sylt
List/Sylt
Germany
Email:jbeusekom@awi-bremerhaven.de

In co-operation with the Common Wadden Sea Secretariat a study was carried out to specify the trilateral Ecological Target "to achieve a Wadden Sea which can be regarded as a eutrophication non-problem Non-Problem area". The work was done in close co-operation with activities in the framework of the OSPAR Common Procedure through which the whole OSPAR Convention Area will be designated as either Non-Problem, Potential Problem or Problem Area with regard to eutrophication. The study consisted of the development of a conceptual model, the analysis of time series, a literature analysis of parameters with potential suitability as indicators of eutrophication and the application of suitable parameters to the Wadden Sea.

In this talk an overview of the project will be given. Focus of the presentation will be the question whether phytoplankton is a useful indicator of Wadden Sea Eutrophication. It is suggested to base the assessment of the eutrophication status of the Wadden Sea on the autumn values of ammonium plus nitrite. Phytoplankton is less useful. Only in the Western Dutch Wadden Sea a relation between nutrient input and mean annual chlorophyll was found. A contrasting situation was observed in the Northfrisian Wadden Sea, where temperature has a dominating influence on the annual cycle of phytoplankton biomass