浮游植物群落对强降雨事件的响应——以湖北长湖为例

Nowadays, lakes are receiving more scientific attentions due to their sensitivity to global climate change. The increasing frequencies of heavy rainfall events exert a complex and diverse influence on the aquatic ecosystem structure and function across space and time, yet the responses of plankton communities are not well understood because the difficulties in sampling. Jianghan Plain is in the area of high occurrence frequency of heavy rainfall events, which causes important impacts to lake ecosystem function in this area. This project will take Changhu Lake as an example, a shallow lake in Hubei province, investigate the magnitude, frequency, and duration of heavy rainfall events and experimentally test the combined effects of terrigenic runoff and thermal variation on eutrophic state and plankton communities. Examine the relationships between extremes and aquatic ecosystems based on multi-parameters (climatic scenarios, hydrology, physico-chemical and biological properties) with emphasis on the roles of heavy rainfall events as controls of plankton community structure and functioning and the responses of the relationships between diversity and ecosystem functioning to heavy rainfall events. As extreme events are predicted to become more frequent and severe during the twenty-first century, this project will help us assess the potential impacts of heavy rainfall events on lake biodiversity and ecosystem functioning and services, and have practical implications for sustainable lake management and protection in Jianghan Plain.

近年来，短时强降雨事件频率和强度的增加给湖泊生态系统结构和功能造成了时间和空间上复杂、多样的影响。但因强降雨过程中实地采样困难，目前人们对强降雨事件作用下湖泊浮游生物群落的响应和适应机制认识仍不足。江汉平原属我国强降雨事件高发地区，这些事件给区域内湖泊生态系统功能造成了重要影响。本研究拟以湖北长湖为例，通过野外观测与原位模拟实验相结合的方法，利用光学显微镜-电镜和流式细胞仪等检测技术和手段，研究不同频率和强度的强降雨事件对水体营养状态和浮游植物群落的影响；分析陆源输入和温度变化在浮游植物群落结构和功能演变中扮演的角色，筛选对强降雨事件响应的敏感指示种；研究强降雨作用下浮游植物群落的稳定性和恢复力；揭示湖泊生物多样性与生态系统功能关系对短时强降雨过程的响应和维持机制，为江汉平原地区湖泊生态系统的可持续管理提供科学依据。

受全球气候变暖影响，极端气候事件的发生频率和强度均发生了显著改变。为科学评估短时气候过程在湖泊生态系统演变中扮演的角色，本研究利用野外观测与原位模拟实验相结合的方法对湖北长湖水质和浮游植物群落动态进行了系统研究。基于1961—2020年长湖流域逐日气象数据，选取9个极端降水指数，运用线性回归分析、相关分析和重标极差分析（rescaled range analysis, R/S）探讨了长湖流域极端降水事件的变化特征及其对气温变化的响应，并对该区域极端降水事件未来演变趋势进行了预测。通过多年野外调查对长湖营养盐和浮游植物群落结构的时空变化特征进行了分析，并探讨了长湖浮游植物群落的演替规律及与其环境因子的关系。此外，本项目同步开展了不同降雨强度对长湖浮游植物群落影响的原位模拟实验，分析了陆源输入在浮游植物群落结构与功能演变中所扮演的角色，初步解析了强降雨作用下浮游植物群落的稳定性和恢复力。研究结果可为江汉平原地区湖泊生态系统的保护与管理提供科学依据。