Study On The Influential Environmental Factors For The Recruitment Of Cyanobacteria In The Sediment Of Shanzi Reservoir

Combined with field monitoring and laboratory simulation, this thesis studied on the influential environmental factors for the recruitment of Cyanobacteria in the sediment of Shanzi Reservoir. In line with the monitoring of water temperature in vertical direction in Shanzi Reservoir from March,2010 to February,2011, which had experienced four levels, respectively, from March to April, May to August, September to December and the next January to February, which were also illustrated the corresponding results, hierarchically appear, distinct, decelerate and disappear. During this period, phytoplankton biomass contained Cyanobacteria, Chllorophyta, Diatom and Cryptophyta and others. Cyanobacteria, as the significant phytoplankton in Shanzi Reservoir, consisting of Anabaena, Microcystis and Oscillatoria and others.Anabaena took up the advantage-time starting from July to September, and Microcystis started from May to September, while Oscillaria lasted from July to September. So the seasonal changes of phytoplankton's biomass were as follow:spring, summer> autumn> winter. According to the relative analyse of phytoplankton biomass and water temperatures in different levels, Cyanobacteria, Chllorophyta, and Diatom highly relative to water temperature, particularly Microcystis and Oscillatoria, and Anabaena was not the same case though. Via the relative analyse in three water layers, it indicated that the biomass of Cyanobacteria dramatically relative to the three water layers, which were surface layer, interlayer and underlayer. And the underlayer Cyanobacteria effected the vertical water-column Cyanobacteria. On the basis of the research on four comprehensive influential environmental factors in Shanzi Reservoir. Temperature and illumination were in favor of the recruitment of Cyanobacteria. Instead, nutritive salt and physical disturbance made inconspicuous effect. High temperature and illumination were able to accelerate the recruitment of Microcystis, but illumination had less influence on the Oscillaria's recruitment than high temperature. After the experimentation of sediment recruitment, it manifested that different kinds of algae (including Cyanobacteria, Chlorophyta and Diatom) could all be recruited and floated up to the surface of water. Under the circumstance of laboratory, the initial recruiting temperature of Diatom and Chlorophyta are relatively low, which recruited approximately at 8℃癈 at first. And the quantities of Diatom were more than Chlorophyta. Furthermore, Cyanobacteria recruited later with a faster speed. In different seasons and different recruiting temperature, and also on the simulated condition of laboratory, Cyanobacteria started to recruit at 10℃in summer and 8℃in winter, because of the quantity and activity of algae sediment in winter. The recruitment of Cyanobacteria in Shanzi Reservoir mainly contained Microcystis and Oscillaria, in combination with the orthogonal experiment, high temperature and suitable illumination were in favor of the recruitment of microcystis, however, Oscillaria was sensitive to temperature but less influenced by illumination. In accordance with laboratory simulation and field monitoring, it could be concluded that the Microcystis and Oscillatoria in Shanzi Reservoir could recruit and float up to the water surface, and temperature was one of most significant influential environmental factors of the recruitment of Microcystis and Oscillatoria in the Sediment.