Algal Physiology and Biooptics, Cruise Report ANT XXI/3 „EIFEX“


It is well known that iron-limited planktonic algae are responding physiologically to iron addition considerably fast on times scales of only a few day or even hours. Variable chlorophyll fluorescence techniques has been used to investigate these physiological changes as well as to simply distinguish iron-replete from iron-depleted cells. A simple goal of our measurements was to track the iron-enriched water patch by a simple surface water flow-trough system using Fast-Repetition-Rate-Fluorescence (FRRF) techniques. Beyond it different techniques were used to follow the photo-physiological changes of the phytoplankton occurring after iron addition and to estimate photosynthesis and primary production. This includes photoacclimation, i.e. effects of solar irradiance, vertical mixing of the water column and water transparency. In addition we were interested in the comparison of different variable chlorophyll fluorescence techniques and in using these different techniques to estimate primary production.
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