形成群体是微囊藻上浮聚集形成水华的重要条件。本项目拟在太湖紊流强度及微囊藻群体大小及形态调查的基础上，利用计算流体动力模型（CFD）测算搅拌和曝气扰动装置的紊流强度，研究紊流对微囊藻群体形成、破碎和形态转变的影响。在群体形成方面，排除紊流强度不同造成二氧化碳浓度差异对群体形成的影响。在群体破碎方面，在较长时间紊流作用下(>24 h)比较搅拌和曝气两种扰动方式下临界紊流强度的差异。在群体形态转变方面，诱导微囊藻粗糙群体向鱼害微囊藻群体的转变，诱导惠氏微囊藻群体向铜绿微囊藻群体的转变。此项研究有望解决目前微囊藻群体形成研究的瓶颈，即诱导单细胞微囊藻形成与湖泊中群体形态相似的微囊藻群体。阐明紊流对微囊藻群体形成、破碎及形态转变的影响规律与机理。同时，提出在自然环境中通过扰动破碎微囊藻群体的技术参数，能够为控制微囊藻群体形成从而防止水华发生的实践工作提供科学依据。

Colony formation is the prerequisites for the freshwater cyanobacterium, Microcystis, to dis-entrain from water turbulence and form surface blooms. This project aims to study the effects of turbulent mixing on colony formation, colony disaggregation/breakup and morphological change of Microcystis, based on the in situ investigations in Lake Taihu of turbulent mixing and Microcystis colonies as well as simulated turbulence via a computational fluid dynamics (CFD) method. This project is to: 1) eliminate the impact of CO2 gradient caused by different mixing intensities on the formation of colonies; 2) compare the critical mixing intensities which disaggregate colonies under two long-term (> 24 h) mixing treatments of stirring and aeration; 3) induce the morphological change of Microcystis colonies, i.e., from rough colonies to M. ichthyoblabe-like colonies and from M. wesenbergii to M. aeruginosa-like colonies. This study is likely to solve the bottleneck issue of current research on colony formation in Microcystis, by inducing unicellular cells to form colonies that closely reflect the field morphologies. Meanwhile, we propose to provide parameters of turbulent mixing that can potentially disaggregate Microcystis colonies in natural environment, and better understanding of applying artificial mixing in controlling formation of Microcystis colonies and preventing the occurrence of Microcystis blooms.