Measurement in a bottle

In addition to the established methods of data collection in ocean research like expeditions, fixed measuring stations and remote sensing, the Marine Physics Group at the Carl von Ossietzky University of Oldenburg operates a new autonomous Lagrangian drifter called „MOSES“, optimized for application in coastal zones. The standard components aboard this drifter comprise an internal memory, a telemetry modem, a GPS unit and an electronic compass, while optional sensors for temperature and conductivity as well as a water sampler can be installed. Recently a device to detect yellow substances and the physiological
state of phytoplankton by fluorometric methods has been developed. Measurement of phytoplankton is based on the „pump&probe“ protocol and is, as well as measurement of yellow substances, implemented with the help of modern
semiconductor technology, including LEDs and photodiodes. The software and hardware of the fluorometer were designed to be highly variable, so different measurement protocols and new parts can be included easily. Experiments in the
laboratory have shown a good correlation in the data between this new fluorometer and a standard laboratory spectrofluorophotometer. Furthermore, the operation
of this device as part of the drifter has been successfully tested in the Wadden Sea, German Bight. Nevertheless, attention has to be paid when interpreting the fluorescence measurements of phytoplankton, because many factors like phytoplankton composition, light history of organisms, temperature and turbidity can alter the results.