The purpose of the cruise is to investigate the subsurface phytoplankton production in the North Sea adjacent to the Dogger Bank. During the summer, traditional thinking has that primary production is suppressed due the nutrient limitation. However, previous surveys have shown significant active production taking place at the height of summer at depths of 20 to 30 m below the surface.
The survey will be composed of 2 repeated transects using a towed undulating CTD on 1 leg, and performing traditional CTD casts on the 2nd leg. These will also include water sampling, phytoplankton nets, and zooplankton pumps. In addition, a drifting buoy equipped with sediment traps and termistors will be deployed at 4°00'E 57°00'N. The buoy will be visited every 24 hours. In the meantime, its position will be monitored, and it will be relocated to its initial start position if its displacement becomes too great.
André W Visser (Technical University of Denmark, National Institute of Aquatic Resources)