33 
risks for individual coastal areas. In a strong simplification of natural processes taking place, 
the availability of light and macronutrients (N,P) and the grazing pressure were considered to 
be the factors controlling primary production and eventually the development of marine 
biomass. In reality, the interacting processes are much more complicated than that and are not 
yet understood very well. Apart from more subtle trace substances (e.g. iron, selenium, 
manganese) and contaminants, it is also life strategies, competition and conditioning, 
pathogenic microorganisms and the direct effects of small-scale turbulence that play a crucial 
role in the development and breakdown of phytoplankton blooms. The relative importance of 
the individual factors is very different depending on the species. Therefore, their complex, 
variable constellations account for differences in species growth and, consequently, the 
seasonal succession in plankton development. Currently available models only provide 
inadequate descriptions of primary production efficiency and plankton dynamics. Suitable 
process formulations and measurement techniques providing a sufficient amount of data for 
the identification and quantification of processes are lacking. With respect to the required 
resolution, the speed and automation level of analytical procedures are of paramount 
importance. 
Fluorescence optical methods (PAM, 1 Hz fluorescence kinetics) for measurements of 
phytoplankton photosynthesis rates have been available for some time now. Flow cytometric 
methods can be used in phytoplankton monitoring and in the investigation of species specific 
growth efficiencies. 
Observation methods / analytical techniques 
For the investigation of seasonal phytoplankton and nutrient dynamics, a station was 
established at the eastern jetty of Büsum harbour as early as 1991. Within the framework of 
the TRANSWATT project of the Federal Ministry of Education and Science, the range of 
variables measured by the station was extended considerably. In weekly intervals during the 
vegetation period (March-October), samples are taken during high water stand for qualitative 
and quantitative phytoplankton analyses and for the determination of nutrient levels (N, P, Si) 
and pigments (HPLC). 
Also the hydrographic variables temperature, salinity and seston content are recorded. Besides 
the permanent stations of BAH which are located in List and Heligoland, the Büsum station is 
the third cornerstone of the German Bight monitoring system. Its main purposes are the 
investigation of conditions in a Wadden Sea area that is subject to strong estuarine influences 
and the development of methods. Measurements of primary production are carried out using 
conventional 14-C technology complemented by pulse amplitude modulation techniques. For 
quantitative/qualitative assessments of phytoplankton stocks, flow cytometric methods are 
used. For regional spatial resolutions, the synoptic seasonal TRANSWATT data have been 
used so far. 
Products and services 
The measurements are made to assess the environmental state of the Wadden Sea ecosystem 
in terms of nutrient loads and eutrophication potential. Changes in species composition due to 
changed nutrient ratios and the intrusion of alien species, the occurrence of toxic species, and 
the detection of possible climate effects are analyzed within the framework of this long-term 
measurement series. The results will be made available to the Trilateral Wadden Sea 
Monitoring Programme as soon as agreement has been reached on responsibilities. They also