减脱水河段生态系统对流量梯度修复的响应机制研究

Human activities have greatly decrease the flow discharge in the river, forming so called "flow-reduced river reach", which has a serious impact on the structure and function of river ecosystem. How to restore the environmental flow regime for the flow reduced river reach scientifically, and maintain the integrity of the ecosystem, is an urgent problem to be solved. However, the response process of the flow reduced rivers ecosystem to the flow restoration have not well been understood, which limit the implementation of the environmental flow. There are some basic problems remain unclear, for example, can all flow-reduced river reach river ecosystems be restored? What are the response processes and response patterns of the ecosystem? In this study, we will select the Xiangxi River as the study object and carry out the in-situ experiment. We study the variation of typical structural and functional indicator to the flow increase in gradient, and find the relationship between flow rate and typical indicators, and then reveal the response model and mechanism of structure and function of river ecosystem to flow restoration, and finally explore the resilience of flow reduced flow river reach. Our result will helpful for environmental flow restoration and management.

人类活动造成部分河段流量大幅减少甚至断流干涸，导致河流生态系统的结构与功能严重退化。如何科学修复减脱河段的生态流量，维持减脱河段生态系统的完整性，是当前迫切需要解决的问题。然而，当前关于减脱水河段生态系统对流量修复的响应过程与恢复力机理了解较为缺乏，是制约科学有效实施生态流量的重要原因之一。是否所有的脱水河流生态系统都能恢复？生态系统响应过程和响应模式是怎么样的？等生态流量内在机理问题仍需进一步探索。因此，本研究以脱水问题突出的香溪河为研究对象，采用原位试验方法，研究流量梯度修复下典型结构与功能性指标的变化规律，构建流量修复率与典型指标之间的相关关系，揭示减脱水河段生态系统结构与功能对流量恢复响应模式与机制，探索典型减脱水河段生态恢复力机理，为减脱水河段生态流量修复与管理提供有效理论依据与技术支持。

本项目针对减脱水河段中生态种群变化机理关系不明确、水文修复生态效应不清以及生态流量修复工作理论依据缺乏等问题，基于野外考察、文献调研、模拟实验、理论分析等手段，从生态系统初级生产者角度出发，以典型结构型与功能型指标为主要生态响应指标进行了研究。开展了断流脱水与引水补水模拟试验，基于16s rRNA的高通量测序技术，分析了模拟水槽中微生物群落结构和环境功能指标对减脱水河段流量梯度恢复的响应，发现随着流量恢复，微生物的多样性有了阶段性提升，群落功能也从单一的元素循环功能恢复了硝酸盐还原、氮呼吸和厌氧呼吸等调节水生生态环境的功能，相关成果发表在Frontiers in Microbiology；通过在短期和长期断流后复流20天的中观实验，研究了生物膜代谢活动的动态变化，发现长期断流会降低生态系统代谢的恢复率，也会对生物膜的碳代谢造成不可弥补的损害，相关成果发表在Environ. Sci. Technol；基于最小二乘支持向量机模型，构建了正常水平和减脱水条件下着生藻生物量随流量及光照变动的定量响应关系，提出了防止减脱水河段水华妨害的流量过程建议，相关成果发表在Journal of Cleaner Production。基于本项目，共发表论文8篇，其中SCI7篇，授权专利2项，培养研究生2名。