Effect of Light Intensity on Growth of Two Species of Algae under Competition Cultures

The specific growth of Microcystis aeruginosa and Scenedesmus obliquus was studied on the conditions of pure culture and three mixed culture with different light intensities and light half saturation constant of each alga was calculated.Result showed that in pure culture,Microcystis aeruginosa got the maximum specific growth rate under 3,000lx,while Scenedesmus obliquus got the maximum specific growth rate under 5,000lx.In mixed culture,the growth rate of the two algae was slower than that of pure culture,and the two algae affected each other.In the 10:1 mixture culture,the inhibition of Scenedesmus obliquus to Microcystis aeruginosa exceeded the inhibition of Microcystis aeruginosa to Scenedesmus obliquus under any light intensity.In the 1:1 and 1:10 mixture culture,the inhibition of Microcystis aeruginosa to Scenedesmus obliquus exceeds the inhibition of Scenedesmus obliquus to Microcystis aeruginosa under low light intensity.No matter which culture system it was in,light half saturation constant for Microcystis aeruginosa growth was lower than that of Scenedesmus obliquus.So Microcystis aeruginosa is more compatible with light than Scenedesmus obliquus.Generally,Microcystis aeruginosa is easier to win in the competition in the comparative low light environment.