湖泊蓝藻水华发生机理研究进展

蓝藻水华是富营养化湖泊常见的生态灾害,通过产生毒素、死亡分解时使水体缺氧和破坏正常的食物网威胁到饮用水安全、公众健康和景观,会造成严重的经济损失和社会问题,揭示其发生机理是进行防治的基础.综述了蓝藻水华发生机理的主要假说和证据,主要分为环境因子(营养盐、氮磷比、温度、微量元素、浮游动物牧食、水文和气象条件等)和生理生态特性(伪空泡、胶质鞘、CO2浓缩机制、适应低光强、贮藏营养物质、防晒、产毒素和固氮等)两个方面；评述了主要新理论,展望了今后的研究.到目前为止的研究表明寻找一两个关键因子并不能阐明蓝藻水华的发生机理.现存的理论或假说尽管已经在蓝藻水华的防治实践中产生重要作用,但仍然未能清楚地阐释其发生的客观规律.认为蓝藻水华是在各种环境因子(外因)的耦合驱动下,水华蓝藻由于其独特的生理生态特性(内因),产生巨大的生物量而在浮游植物群落中占绝对优势,在合适的水文气象条件下集聚于水表而形成.因此水华机理的研究应同时关注水华蓝藻的生理生态学规律和蓝藻水华发生的各种环境条件.不同环境因子协同影响水华蓝藻的不同生理生态特性的表达,从而影响水华的发生过程,将可能是以后研究的重点.蓝藻水华机理的研究在微观方面正趋向于应用分子生物学手段分析蓝藻生理过程,宏观方面则将广泛应用遥感遥测技术观测全湖蓝藻的变化规律.今后加强对水华蓝藻生理生态特性的基因表达与调控和环境多因子耦合作用于蓝藻水华过程的研究将有重要意义.蓝藻水华的机理研究包括现象、过程和原因3个层次的问题,通过大量的现象和过程的研究,不断揭示其发生过程中水华蓝藻的群落演替、种群发展、细胞活性和分子机理等变化规律,才能找到其发生的真正原因,为其防治提供理论依据和更好的治理措施.在蓝藻水华防治方面,控制营养盐和生态修复可能将是今后很长时间内最根本最有效和最具操作性的方法.

Progress and prospects on cyanobacteria bloom-forming mechanism in lakes

Cyanobacterial blooms present risks for drinking water safety, public health and landscape, which cause serious economic losses and social problems. To reveal cyanobacteria bloom-forming mechanism is the basis for cyanobacterial blooms prevention. We reviewed the main hypothesis and evidences of the mechanism of cyanobacteria bloom-forming, mainly including environmental factors (nutrients, TN:TP ratio, temperature, trace elements, zooplankton predation, hydrological and meteorological conditions, etc.) and physio-ecological characteristics (pseudo-vacuoles, sheath, CO₂ concentrating, adapt to low light intensity, the storage of nutrients, sunscreen, produce toxins and nitrogen fixation, etc.), then commented the new theories about cyanobacteria bloom-forming mechanism and prospected the future research. The knowledge of understanding one or two key factors that does not clarify the mechanism of algal blooms. The existing theories or hypothesis have still failed to explain the objective laws of the cyanobacteria bloom-forming clearly even though they have played an important role in the practice of prevention and control of cyanobacterial blooms. Cyanobacterial blooms were multiple driven by environmental factors (external factors) with the advantages of its unique physio-ecological characteristics (internal factors). Hence, cyanobacteria could produce enormous biomass and dominate the phytoplankton community, then bloom under water surface under suitable hydrological and weather conditions. Research on cyanobacteria bloom-forming mechanism should also concern the two aspects. It will be the focus of future research on collaborative expression of different physiological and ecological characteristics of cyanobacteria in different environmental factors, thus affecting the occurrence of algal blooms. The research on mechanism of algal blooms will expand towards the micro and macro level. Molecular biology methods will be used to study cyanobacterial physiological processes at the micro level. At the macro level, remote sensing technology will be used to observe biomass spatial-temporal cyanobacteria variation. It is very vital in the future to strengthen the research on the gene expression of cyanobacterial physio-ecological characteristics and environmental factors coupling affect on the cyanobacterial blooms process. The further investigation that should be interested for us: (1) What is the gene expression and regulation mechanism of Microcystis to form colonies? (2) How do environmental factors affect gene expression and regulation process of the cyanobacteria? (3) What are the quantitative relationships between meteorological factors (radiation, wind, rainfall, etc.), the hydrology or the hydrodynamic process and the growth and distribution of cyanobacteria? (4) What are the quantitative relationships between nutrients and cyanobacterial growth or reproduction? Cyanobacteria bloom-forming mechanism researches include three levels: phenomena, processes and causes. To reveal the disciplines of cyanobacterial bloom in phytoplankton community succession, population development, cell activity and molecular mechanism by a large number of phenomena and processes research, will find the real cause of cyanobacterial blooms and provide a theoretical basis, and better governance measures for the prevention and treatment.