In the open sea pelagic (living in the free water) micro-algae and bacteria are those organism, who use light energy for the conversion of inorganic material to organic substances. This ability makes them the base level of  he marine food web.  By turning over gaseous  compounds like oxygen ,carbon dioxide and many other climate-relevant gases these organisms are important for the regulation of the global climate.
A prerequisite for this function is the posession of  photosynthetic pigments with  chlorophyll a  as the most important one. A large proportion of the visible colour of the water is produced by these pigments, so that the analysis of the ocean colour allows conclusions on the density of algal population. For this purpose satellite images are used which enable surveys of large  areas simultaneous and in high temporal resolution.. In the image gallery typical pelagic microalgae and photosynthetic bacteria  are presented in light- and electron microphotographs. The displayed organisms  are of particular importance in various biological monitoring projects of  the IOW in  different marine regions.

This image collection is still under construction and will be constantly extended.

The photographs were taken by R. Bahlo, S. Busch and R. Hansen