Actual standard and further development of an algal fluorescence bioassay.

A measurable result of nearly all influences which affect the primary processes of photosynthesis is a change of the fluorescence emission of a plant. This change of the fluorescence emission due to substances which affect or block photosynthesis is well known since the work of Kautsky (1943). The fluorescence test used here, due to the optical characteristics of the photosynthetic pigments (chlorophyll fluorescence greater than 660 nm), allows the measurement of the fluorescence of algae (Scenedesmus sp./Chlorella sp.). The measurement process is demonstrated. The results show the principal function of the bioassay and its sensitivity. Effects of the algae can be demonstrated at a very low pollutant concentration. The time from the dosage of a toxicant to a clear reaction of the algae is very short (5 min). The aim of the actual research is the determination of the sensitivity of the bioassay to a representative number of chemicals and possible interactions with physical parameters. A connection to a data system, e.g., computer registration of the fluorescence curve and an automated process control, will be the next step.