Abstract:  The rapid growth of algae, which is a combined result of its physiological characters and environmental factors, contributed largely to the water bloom. Microcystis aeruginosa, a common algae in water bloom, is chosen as the research object to analyze the impacts of environmental factors including nitrogen and phosphorus (concentration, fraction and the ratio of nitrogen to phosphorus), light (light intensity and light period), temperature, pH, salinity, and disturbance at different levels on the algae growth. The analysis is carried out by summarizing experimental researches and theoretical achievements in China and abroad. Environmental conditions favorable for algae growth are summarized as sufficient nutrient, appropriate light and temperature, and slow water flow. Countermeasures to water bloom are presented. Reducing the concentration of nutrient and changing the ratio of nitrogen to phosphorous are believed to be the most efficient approaches of controlling algae. Adjustment of pH, light, salinity and temperature, as well as hydrodynamic approaches are also put forward.

Key words:  environmental factors, freshwater algae, Microcystis aeruginosa