From the chlorophyll data it is evident that due to the patchiness taking samples from research ships would only be successful if the cruise had been carried out at the "right" times and at the "right" locations. On the other hand, stationary (fixed) buoys would only by chance detect these algal blooms if they had been anchored within the area of the bloom. Contrary to this, transects with ferries have a greater chance for the assessment of algal blooms. If these measurements are combined with satellite measurements-as we plan to do in the very near future with ENVISAT - the "fate" of algal patches even can be followed. In the case of Figure 5 this means that one can decide if the algal bloom broke down or was drifting out of the region. Simultaneously the ferry data can be used for calibration of satellite data (in situ truth). Since in the North Sea the satellite coverage is poor due to clouds, a numerical model could be used for further improvement of the assessment of algal blooms.

　

　

It could be shown that ferry boats or ships-of-opportunity equipped with automated systems for water quality measurements are a suitable tool which can supplement existing "conventional" monitoring in coastal areas and shelf seas. However, integrated monitoring strategies which are carried out by combining sampling from ships, automatic fixed stations, automated ferry systems, remote sensing and numerical models do not only require good concepts and strategies in order to achieve the maximum of information with the minimum of resources, but also requires suitable tools to merge the different types of data (different spatial and temporal scales).

　

At the time being, some of these tools and methods are now developed and tested in EU projects, among which is the "FerryBox" project, in which eight ferry routes will be used for an comparison of different European ferry "boxes". After completion of the different EU projects strategies should be developed which demonstrate how future integrated monitoring systems can be operated and show the benefits of enhanced coverage and information density.

　

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