In order to specify plankton organisms of about 10 to 500 µm size one needs to look through the microscope. This type of analys is is one of the three taxonomic methods we use along with flowcytometry and phytoplankton pigment analysis by means of HPLC (High Performance Liquid Chromatograpy). We mainly use inverted microscopes which are also good for quantitative analysis of the Phyto- or Microzooplankton in water samples. Some of the microscopes are equipped with a UV-excitation lamp, suitable objectives and filters, to perform fluorescence microscopy, which could be very helpful e.g. to distinguish between heterotrophic and autotrophic organisms. A connected camera with monitor is a good tool for teaching and outreach activities.
contact: Annegret Stuhr
Confocal Laser Scanning Microscopy
Although many of them are so tiny that they cannot be recognized with the naked eye, organic particles and small organisms such as bacteria, unicellular algae and copepods play important roles in the marine food webs and in the global oxygen and carbon cycles. In order to understand, in detail, their significance for particle and energy fluxes in the oceans, it is often necessary to analyze the organic particles and the organisms with high-resolution microscopy techniques. We apply a well-equipped confocal laser scanning microscope (CLSM) enabling three-dimensional visualizations of the structures of interest with a resolution of a few hundred nanometers.
The CLSM produces sharp and detailed micrographs of optical sections through the samples. Based on this series of micrographs precise three-dimensional visualizations can be created. Different components and compounds of marine particles, gels, aggregates and biofilms can be visualized by applying specific fluorescence dyes and markers and by using autofluorescences. A special application of the CLSM is to analyze gel particles, which form from dissolved organic matter and play an important role in the organic carbon cycle of the oceans, and their associated microorganisms.