Rapid Monitoring of the Stress Responses and Toxicity in Green Microalgae Cultures Using Pulse-Amplitude Modulated (PAM) Fluorometry

Green microalgae are widely used as model organisms in ecotoxicology due to their sensitivity to environmental stressors and their critical role in aquatic ecosystems as primary producers at the bottom of the food web. Pulse-Amplitude Modulated (PAM) chlorophyll fluorometry is a non-destructive, rapid and informative method for assessing photosynthetic efficiency and culture health, particularly through parameters such as the maximum photochemical activity of PSII (F_v/F_m) and effective PSII activity (Φ_PSII). Despite the growing number of studies utilizing PAM as an indicator rather than as a direct tool to evaluate microalgal stress responses, there remains a lack of standardized, accessible data for these key photosynthetic indicators. In this review, we analyze 38 sources, including 35 original research articles and 3 foundational references, to compile and compare reported values of F_v/F_m and Φ_PSII across various green microalgae species exposed to a wide range of chemical and environmental stressors. We highlight species-specific differences in sensitivity, identify underrepresented contaminants such as ionic liquids and artificial sweeteners, and emphasize the need for systematic numerical reporting in future research. PAM is an excellent and reliable technique for rapidly assessing culture health of green microalgae and their photosynthetic performance in various culture conditions and the vast array of chemical and physical stressors.