Detailed information about the temperature, conductivity and oxygen of the water column have been carried out with a CTD – Rosette combination (Seabird 911+) with additional oxygen sensor. Chlorophyll-a measurements and turbidity measurements have been carried our with a Wetlab CHL sensor and Dr. Haard turbidity sensor. The Rosette contains 18 bottles with a volume of 10 l.To investigate the distribution of T .heimii cells and acantharien in the upper water column, water samples have been collected on a depth transect over the deep chlorophyll maximum. Directly after recovery, samples have been gently filtered through a 20μm and 10μm sieve and counted, to avoid dissolution of the acantharian. Counts have been carried out using an Axiovert microscope (Zeiss) under 400x magnification.