Light and temperature effects on the growth rate of three freshwater algae isolated from a eutrophic lake

Effects of light and temperature, on the growth of three freshwater green algae isolated from an eutrophic lake and identified as Selenastrum minutum, Coelastrum microporum f. astroidea and Cosmarium subprotumidum were studied in batch cultures under non- nutrient limited conditions. Experiments were performed to determine the growth rate over a wide range of light intensities ( 30 - 456 mumol m(-2) s(-1)) and temperature ( 15 - 35degrees C), using a 15/ 9 ( light/ dark) photoperiod cycle. The maximum growth rates and the optimum light intensities at a temperature of 35degreesC were 1.73 d(-1) and 420 mumol m(-2) s(-1)for Selenastrum minutum, 1.64 d(-1) and 400 mumol m(-2) s(-1) for Coelastrum microporum and 1.00 d(-1) and 400 mumol m(-2) s(1) for Cosmarium subprotumidum. The results were fitted with the mathematical models of Steele ( 1965), Platt & Jassby ( 1976) and Peeters & Eilers ( 1978). Steele's function and equation of Platt & Jassby don't describe correctly the relationship between the growth and light intensity. In the opposite, the equation of Peeters & Eilers provides the best fit for the three species.