Study On Growing Physiological Character And Competitive Predominance Of Blue-Green Algae

The problems of Lake-eutrophication are more severe than before with fast development of agriculture&industry and discharge of waste in the world, and the water-bloom brings intimidations for using of water resource,producing and health of livestock by eutrophication, Now the mechanism study of influence of environmental factors on breaking out water-bloom of blue-green algae has been a hotspot and an important direction of international water environmental study. The paper used many algae which were separated from Taihu-lake, such as Microcystis aeruginosa, Scenedesmus quadricauda and Nitzschia palea to study the growing physiological character and competition predominance at different P concentrations, pH and under different light, temperature, in order to disclose mechanism of water-bloom of blue-green algae, supply the academic base and instructional principles for prevent water-bloom of blue-green algae. The study showed: 1.The μmax of M.aeruginosa, S.quadricauda and N.palea for P were 0.806 d-1,1.378 d-1 and 1.411 d-1, Ks are 0.003mg/L(P),0.012 mg/L(P) and 0.008 mg/L(P) respective, the minimum P for cell are 2.21×10-11mg/cell,5.32×10-11mg/cell and 1.36×10-10mg/cell.They showed cells of blue-green algae had stronger absorption ability for P than green algae and diatom. 2.The μmax of M.aeruginosa and S.quadricauda for light were 1.531 d-1 and 2.723 d-1, Ks are 4.614×103Lux and 8.271×103Lux respective. They showed the requirement of blue-green algae for light was lower than green algae. 3.M. aeruginosa and S.quadricauda could grow fast in the M11 culture medium, It showed blue-green algae and green algae all could adapt M11 medium primely to grow,M11 could use as a common culture medium. 4.In the competition of M.aeruginosa, S.quadricauda and N.palea under different light, when light was lower than 4000Lux, relative predominance of M.aeruginosa increased with increasing of light; when light was higher than 8000Lux, the dominance disappeared. They showed proper low light was beneficial to gain predominance for blue-green algae. 5.In the experiment of temperature, relative M. aeruginosa, the competitive predominance of S.quadricauda and N.palea was least at 28℃, was larger at 15℃, 20℃and 35℃.It showed proper high temperature was help to compete for blue-green algae. 6.In the simulative lake medium of 0.012,0.112,0.412 and 1.612mg/L P concentration, S.quadricauda was dominator, and pH was large than 10.0; after adjusted pH to 5.80 with 0.04mol/L HCL, the predominance of S.quadricauda was more clear under P concentrations which were lower than 0.412mg/L, but M. aeruginosa was the dominator under 1.612mg/L P concentration. It showed pH influenced competition of blue-green algae and green algae together with P concentration 7.In the simulative lake medium, relative M.aeruginosa, predominance of S.quadricauda increased with increasing of P concentration, and the predominance was largest under 1.612mg/L; predominance succession from N.palea to M.aeruginosa was most prominent at 0.412mg/L. It showed proper P concentration was in favor of winning the competitive predominance for blue-green algae.