Chlorophyll a fluorescence and photosynthetic activity as tools for the evaluation of simazine toxicity to Protosiphon botryoides and Anabaena variabilis.

On studying the effect of simazine on Protosiphon botryoides and Anabaena variabilis, data revealed that chlorophyll a content and dry weight were decreased with the increase in simazine concentration. High concentration of simazine (0.8 mg L(-1)) reduced gross photosynthesis and carbohydrate content, whereas protein content and respiration rate were increased. Algal cell recovery from simazine toxic effect occurred after 2 and 4 days for Anabaena and Protosiphon, respectively, which may be attributed to the difference in algal genotype of the tested organisms.