FerryBox - application of continuous water quality observations along transects in the North Sea

In order to distinguish between anthropogenic and natural changes in an ecosystem, the environmental parameters and the driving forces need to be monitored in different temporal and spatial scales. The limitation of conventional monitoring methods particularly with regard to temporal and spatial resolution is often a serious hindrance to a better understanding of marine ecosystems and the underlying biogeochemical processes. The use of unattended automatic observing systems onboard of ships of opportunity offers a cost-effective and reliable possibility to obtain regular observations of near-surface parameters with a high spatial coverage and temporal resolution. In the Southern North Sea the application of the so called FerryBox systems has been proved since 2002. FerryBoxes have been installed on different ferries and cargo ships as well. The system allows high frequent monitoring of oceanographic parameters (temperature, salinity, turbidity) as well as biological relevant parameters such as chlorophyll, nutrients, oxygen and pH along a transect. In combination with remote sensed data the spatial limitation to a certain transect can be overcome. On the other hand the data from the FerryBox can be used as ground truth data for the remote sensing data. Special events like strong short-term algae blooms, which will be detected only occasionally by standard monitoring methods, can be studied in detail and related to variations in influencing factors such as temperature, wind and nutrient load. Continuously measured high accurate oxygen data can be used to estimate productivity along the transect. However, due to its limitations (surface measurements, certain ship tracks only) only a combination of research ship cruises, buoy measurements at strategic locations, remote sensing and numerical modeling will give the deep insights needed for an understanding of the ecosystem as a prerequisite for future management options.