Abstract: Growth of Microcystis aeruginosa and Scenedesmus obliquus as affected by temperature were observed in monoculture and mixed-culture varying in inoculation density under controlled laboratory conditions. It was found that with the temperature varying within the range of 7 - 35℃, the specific growth rate of M. aeruginosa increased with the temperature, while that of S. obliquus rose first and then fell with 25℃ as its turning point. In the mixed culture, competition between the two algal species affected their growth rates, making them lower in the mono-culture, and in all the three mixed-culture experiments, the specific growth rate of M. aeruginosa was higher than that of S. obliquus M. aeruginosa grew the slowest in the mixed culture 10:1 (Microcystis aeruginosa: Scenedesmus obliquus) in inoculation ratio, whereas S. obliquus did in the mixed culture 1:10 in ratio. In all the mixed-culture experiments, regardless of inoculation ratio and temperature, M. aeruginosa displayed stronger competitive inhibition than Scenedesmus obliquus did. The interspecific competitive inhibition, varied with the temperature, either intensified or weakened, but M. aeruginosa was always more competitive.

Key words: Microcystis aeruginosa, Scenedesmus obliquus, temperature, mono-culture, mixed-culture, interspecific competition