三峡库区水位脉动条件下两种水华蓝藻碳磷营养策略研究

Cyanobacterial Microcystis and Aphanizomenon have been recognized as the most dominant bloom-forming organism in eutrophic water bodies. The mechanism of their formation and persistence in freshwater bodies has been always the focus of research world widely due to their harmful effect on aquatic ecosystems and their potential hazard to human health. To investigate the phenomenon of the succession in Microcystis and Aphanizomenon during the different water level in the Three Gorges Reservoir, this project will focus on the responses of these two cyanobacteria to the water cyclic pulsing from the key limiting factor of carbon and phosphorus. The research will be taken by the combination of the laboratory experiment tests and filed investigation. With the comparison study of organic and inorganic carbon utilization, different phosphorus form absorption and the synergistic effect of these two nutrients at varying light, temperature and flow rate in the two cyanobacteria, and in situ monitoring of the field water in the Three Gorges Reservoir, the present study will illustrate the physiological and ecological responses and underlying mechanisms of Microcystis and Aphanizomenon to carbon and phosphorus. Then it will reveal the trophic strategy of the persistence and succession in Microcystis and Aphanizomenon influenced by water cyclic pulsing in the Three Gorges Reservoir. The results of this research project will provide theoretical and practical significance in further understand the mechanism of the dominancy and persistence of cyanobacteria bloom in large reservoirs, and may be implicated in the water bloom prevention and controlling by means of hydrodynamic regulation.

作为蓝藻水华常见的优势种－微囊藻（Microcystis）和束丝藻（Aphanizomenon）已对水体产生严重的危害，对其研究也成为当前国际研究的热点。针对三峡库区不同水位调度期微囊藻和束丝藻种群动态演替的现象，本项目拟从碳、磷这两个关键的限制因子着手，开展微囊藻和束丝藻在水位脉动条件下的响应研究。通过室内模拟对两种水华蓝藻在不同光热条件及水流速度下有机碳和无机碳吸收利用、不同磷形态的摄取以及碳、磷协同作用的响应机制等比较研究，同时结合三峡库区野外水体不同水位下的原位监测比较，阐明微囊藻和束丝藻在碳、磷及其协同作用的生理生态响应机制，进而揭示三峡库区水位脉动条件下微囊藻和束丝藻种群优势维持和演替的碳、磷营养策略。该研究对进一步了解影响大型水库蓝藻水华暴发和优势维持机制，以及利用水动力调控进行水华防治具有重要理论和实际意义。

本项目围绕水库运行下的藻类营养策略研究，从碳、磷这两个关键的限制因子着手，开展典型水华蓝藻在水位脉动条件下的响应、原位受控实验与室内机理实验研究，获得了以下主要成果：.（1）三峡水库水华形成、演替随水库调度运行具有独特的个性，动态的水库运行对其产生深刻影响。低水位运行期：光、热、营养物输入为蓝藻水华形成创造了优越的能量和物质资源，但河道型水库水文过程将对蓝藻生长、生物量积累与水华形成产生破坏。高水位运行期：水库积累有丰富的无机营养物，但光热条件限制了蓝藻生长而诱使其他藻种成为优势；泄水期：水温、光照、营养物浓度均为藻类生长创造了良好的生境条件，是水华敏感期，但会因不同的水文水动力条件诱导出现不同类型水华。.（2）研究发现：温度和光照条件对典型水华蓝藻的光合放氧过程有明显的促进作用，随着温度和光照的升高，最大光合放氧速率和饱和光强有显著提升。低紊流扰动强度对水华鱼腥藻的C的吸收产生了促进作用，而较高的紊流扰动对藻细胞的C吸收产生了一定的抑制作用。一定强度的紊流扰动能明显促进水华蓝藻的生长。紊流扰动对蓝藻细胞光合活性及单位细胞内叶绿素含量影响不显著，而对藻细胞磷吸收速率有显著的影响。紊流扰动下水华鱼腥藻藻细胞形态发生显著变化，细胞尺寸减小，比表面积增大。推测藻细胞通过减小细胞尺寸，加快磷吸收速率以适应紊流扰动环境。.（3）通过原位流速实验发现，夏季低水位阶段澎溪河水域光热充足，但流速升高对藻类原位生长速率具有一定影响。大体上，高阳平湖水域藻类原位比生长速率与流速呈对数函数关系。冬季高水位运行期间，流速的增加将可能在一定程度上促进水柱扰动，成为维持藻类在上层水体受光生长、吸收碳磷营养盐的主要因素。. 本项目执行期间发表论文14篇，其SCI 5篇，EI 2篇，CSCD 7篇。申请并已进入实质性审查阶段的发明专利6件，获权实用新型专利4件，培养研究生7名。研究成果为利用水动力调控进行水华防治提供重要理论参考。