Photophysiology and primary production of phytoplankton in freshwater.

In the last 10 years enormous progress has been made in developing new instruments to collect physiological data from natural phytoplankton. In this review we summarize the motivation which has powered this engagement and focus on new technologies used to measure fluorescence, absorption and biochemical compositions of natural phytoplankton cells from nature. Combining the knowledge of phytoplankton structure along with taxon-specific measurements of photosynthetic activity and biochemical cell composition, can lead to new models which increase the reliability of water quality prediction. Furthermore, recent progress in the analysis of photophysiological fitness of phytoplankton cells has revealed new knowledge about the phylogenetic diversity of metabolic strategies to cope with light and nutrient stress. Future progress in single cell analysing systems will be discussed.