Effects of Interactions of Irradiance, Daylength, and Temperature on Division Rates of Three Species of Marine Unicellular Algae

Abstract

Rates of light-saturated division of Thalassiosira fluviatilis and Isochrysis sp., marine unicellular algae, were regulated by temperature and daylength at 25 C, and primarily by temperature at 20 C or less. The rates for Chroomonas salina appeared to be regulated by temperature and daylength at temperatures between 10 and 25 C, with maximum effects of daylength occurring at temperatures of 20 and 25 C. Physiological mechanisms through which temperature and daylength interact to regulate division rates of unicellular algae are discussed.