变化环境下的云南高原深水湖泊光热特征及浮游植物的生理生态响应

Global warming and ultraviolet radiation (UVR) enhancement are two major environmental issues facing the world, has been impacting on lake ecosystem profoundly. The variation of optical and thermal regime is the basic driving force of ecological processes in lake. Phytoplankton is a main primary producer in lake, which is also the direct responder of these change. However, there is limited knowledge on the cumulative effects of UVR-climate change interactions on the lake ecosystem, which also have not been thoroughly investigated in Yunnan Plateau, faced with the grim situation of climate warming and UVR enhancement. Based on the research approach and methodology of the comparative and transformational limnology and the basic principle of phytoplankton physio-ecology, we intend to study on Yunnan Plateau lakes and focus on the typical oligotrophic deep lake named Fuxian in this proposal, the lake is sensitive to environmental changes and has a trend of deterioration of water quality. Furthermore, we will combine with historical data analysis, field investigation, laboratory simulation and in-situ testing to study the joint effects of climate warming and UVR enhancement on optical and thermal regime and the comprehensive physio-ecological response characteristics of phytoplankton including photosynthesis, physiological activity, primary productivity, population dynamics and community structure. The results can provide theoretical supplement of the evolution and response mechanism of lake ecosystem and recommendation for lake conservation and management under changing environment.

气候变暖、紫外辐射增强是全球面临的重大环境问题，对湖泊生态系统具有深远影响。光、热是驱动湖泊生态过程的关键物理因素，主要初级生产者浮游植物则是最直接响应者。然而，关于气候变暖、紫外辐射增强对湖泊生态系统的联合累积影响效应与机制的认识仍然有限，低纬度中等海拔地区的云南高原（气候变暖、紫外辐射增强形势严峻）湖泊更是缺乏系统研究。本项目拟以云南高原湖泊为研究对象并重点关注典型寡营养深水湖泊抚仙湖（对环境变化敏感、有水质恶化趋势），基于比较湖沼学、转化湖沼学的研究思路和浮游植物生理生态学基本原理，结合历史数据分析、野外调查、室内模拟和原位试验等手段，研究气候变暖、紫外辐射增强对湖泊光热格局的联合影响以及浮游植物光合作用、生理活性、初级生产力、种群动态与群落结构等生理生态综合响应，拟取得的结果可为深化认识变化环境下的湖泊生态系统演变机制与响应机理提供理论补充，为湖泊生态环境保护与管理提供建议。

光、热是驱动深水湖泊生态系统诸多过程的关键物理因素，浮游植物不仅是其最主要的直接响应者，亦是湖泊生态系统主要的初级生产者；云贵高原是我国五大湖区之一，其中云南高原是云贵高原湖区的重要组成部分，且气候变暖、紫外辐射增强形势严峻，但其有关研究相对薄弱。本项目以云南高原典型（深水）湖泊为重点研究对象，基于物理湖泊学和藻类生理生态学基本原理，有效结合历史数据分析、野外调查、室内模拟和原位试验等技术手段，比较了云南高原程海、滇池、洱海、抚仙湖、泸沽湖和阳宗海水体紫外辐射与光合有效辐射的衰减特征及其主控因子的湖泊间异质性，以抚仙湖为重点识别了其紫外辐射、光合有效辐射和热力分层的时空变化，揭示了其1980s以来水体透明度的降低主要是因为有机质含量升高且开展了不同营养状态湖泊间的比较研究；比较了蓝藻门、绿藻门和硅藻门典型藻种对温度升高、紫外辐射增强和营养盐增加的响应异质性，识别了抚仙湖浮游植物功能群的季节演替主要受水温和氮磷营养盐的影响，刻画了紫外辐射对浮游植物的影响与季节、藻类组成和营养盐条件有关，揭示了以滇池、洱海和抚仙湖为代表的湖泊浮游植物历史变化与营养状态、藻类组成等有关；识别了程海真光层深度和浮游植物生物量与初级生产力的时空变化特征，程海和阳宗海水体分层特征及其对浮游植物生物量的潜在影响；此外，还综述了1991年以来硅藻的研究趋势。已取得的研究结果，为进一步深化认识气候变化背景下的云南高原湖泊生态系统的演变机制与响应机理提供了基础数据和理论探索，可为湖泊生态环境保护与管理提供建议。