Vertical migration of Microcystis and Scenedesmus and its ecological significance
Wu Shengcai1,2, Chen weimin2
1. Yancheng normal college, Yancheng 224002, Jiangsu, P. R. China; 2. Nanjing institute of geography & limnology, Chinese Academy of Science, Nanjing 210008, China
The vertical migration of cell of two algal species (Microcystis aeroginosa and Scenedesmus obliquus), represented by attenuation coefficient (K) and sinking velocity (V), was studied in self-made sinking column. Results showed that the property in vertical migration of these two species were different in 4 irradiation intensities and 3 growth phases. For Scenedesmus obliquus colony, the Kmin is -0.0021 cm-1 (migrating upward) and the Kmax is 0.0065 cm-1 (sinking downward),and the value of relative parameter is-0.0029 cm-1and 0.0036 cm-1 for Microcystis colony respectively. Most values of R2 of exponential simulation was more than 0.6, which showed R2 can reflect the property of cell sinking and the variation of cell density according to depth exponentially. The maxim of sinking velocity (Vmax), 4.681cm·h-1 (downward), was obtained in Scenedesmus colony in exponential phase, and the Vmin of migration velocity,-1.790 cm·h-1 (upward) was present in stable phase of Microcystis colony. The data gained in this study may be a direct evidence to explain the mechanism of population domination of Microcystis spp.
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