[Effect of nitrogen and phosphorus on growth and competition of M. aeruginosa and S. quadricauda].

In order to disclosure the formation rule of predominant species in different nutrition conditions, three kinds of nutrition concentration were selected for the competition experiments with the common species of blue-green algae bloom Microcystis aeruginosa and the common species of green algae bloom Scenedesmus quadricauda. The competition relation was analysed by the competition parameters. The results indicate, in low nutrition, Scenedesmus quadricauda can stimulate the growth of Microcystis aeruginosa in mixed culture, the simulation becomes evident in low N/P ratio and M. aeruginosa can also stimulate the growth of S. quadricauda; in eutrophic condition, inhibition effect is connected with N/P; in hyper-eutrophic condition, the inhibition effect of S. quadricauda on M. aeruginosa is about three times as that of M. aeruginosa on S. quadricauda, and the effect of N/P ratio on competition inhibition parameters isn't evident. In low concentration N and P water, M. aeruginosa is easy to become predominant species, while in high concentration N and P water, S. quadricanda is easy to become predominant species.