Study of dependency between culture growth and photosynthetic efficiency measured by fluorescence induction in Selenastrum capricornutum inhibited by copper.

Fluorescence parameters were reported earlier to be reliable indicators in the determination of heavy metal toxicity in algal cultures (Samson and Popovic, 1988). In this report, the effects of copper on Selenastrum capricornutum culture growth and photosynthetic efficiency were studied at different copper concentrations. By using the complementary area of variable fluorescence kinetics and the cell counting method, we determined the level of toxicity at different copper concentrations and the ability of algal populations to adapt to inhibitory effects. Algae exposed to copper concentrations higher than 0.5 mg/liter were incapable of recovering biochemical and physiological processes related to photosynthesis after 96 hr. A recovery process in algal culture intoxicated with 0.5 mg/liter was revealed only by fluorescence induction phenomena. Here, the authors justify the use of fluorescence induction parameters in the investigation of copper stress effects on algal populations and their short-term adaptation phenomena.