Longterm Ecological Research
Hydrography, Nutrients and Phytoplankton Biomass
Water column processes play an important role in the cycling of nutrients and organic matter, accounting for about 50% of the total (benthic plus pelagic) annual production and remineralisation. The Sylt-Rømø Bight is heterotrophic. Most of the organic matter and nutrients that are turned over in the Wadden Sea are imported from the North Sea (see: exchange with the North Sea). The shape of seasonal cycle of nutrients gives information on annual differences in timing and intensity of transformation processes. This approach has been succesfully applied to long term data from the Dutch Wadden Sea (see: exchange with the North Sea) and is now being investigated for the Sylt-Rømø Bight.
Evaluation of the long term data will focus on the following points:
- Intercomparison with other Wadden Sea areas.
- Influence of wind and weather.
The time series are closely linked to the overall ecosystem view presented here (see: Ecosystem analysis). Present research focusses on transformation processes of nutrients. In this context, we have extended the original parameter set (Salinity, pH, inorganic nutrients, chlorophyll, suspended matter, part. C and N) to include dissolved organic nutrients and particulate organic phosphorus and biogenic silica.
selected literature:
van Beusekom, J. E. E., Brockmann, U. H., Hesse, K.-J., Hickel, W., Poremba, K., and Tillmann, U. (1999). The importance of sediments in the transformation and turnover of nutrients and organic matter in the Wadden Sea and German Bight. German Journal of Hydrography , 245-266.
van Beusekom, J. E. E. van and V. N. de Jonge. Long-Term Changes in Wadden Sea Nutrient Cycles: Importance of organic matter import from the North Sea. Hydrobiologia . accepted.
van Beusekom J. E. E., F. de Jong, H. Fock, S. Diel-Christiansen, B. Christiansen. (2001) Wadden Sea Specific Eutrophication Criteria. Wadden Sea Ecosystem 14, Common Wadden Sea Secretariat, Wilhelmshaven, Germany. 116 pp.