酸雨调控浮游植物群落结构变动的生理生态机制研究：以新安江流域为例

The ecological effects of freshwater acidification induced by acid rain has aroused great attentions, China has become the third largest region with acid precipitation besides Europe and North America in the world. Former studies have shown that freshwater acidification could affect the community structure and biodiversity of phytoplankton within different phylum, however, eco-physiological behavior along with acid stress has been hardly explored. Our recent study showed that species in the same genus or even two strains of the same species, photosynthetic performances to acid stress were significantly different. Therefore, acid rain regulated phytoplankton community structure change should have linked closely with the diversified photo-physiological characteristics of different species. Thus, the scientific question of our study aimed at the eco-physiological mechanisms of phytoplankton community structure change regulated by acid rain. Typical dominant algae species of different phylum, which were isolated from acid rain controlled region of Xinan Jiang watershed (the first national trans-provincial eco-compensation experimental area), will be used as the research material. Firstly, the laboratorial experiments, from the perspective of physiology (photosynthetic and biochemical parameters), will be carried out to investigate the responses and adaptive mechanisms of those isolated algae to short and long term acid stress. Meanwhile, indoor and outdoor simulated competition experiment will be carried out to further illustrate the potential effects of acid stress on competitive advantage of phytoplankton in different phylum. This proposal, therefore, provides relevant scientific data and theoretical basis to evaluate the eco-physiological mechanism of phytoplankton community structure change and succession trends to acid rain. The results acquired also try to provide advices on the ecological safety and aquatic ecosystem protection.

酸雨引起的淡水酸化及其生态效应已经引起科学界的广泛关注，我国已成为继欧洲、北美外世界第三大酸雨区。以往研究表明水体酸化可对浮游植物群落结构及多样性产生影响，然而决定其生消变化规律的生理生态机制尚不清楚。我们近期的研究表明，同一属的不同种以及同种藻的不同株系，光合生理对短期模拟酸雨的响应都有着显著差别。因此，酸雨对浮游植物群落结构的调控理论上应与不同类型藻体生理、生化过程的差异性响应有着必然联系。为此，本项目针对“酸雨调控浮游植物群落变动的生理生态机制”这一科学问题，选取酸雨控制区新安江流域（全国首个跨省水生态补偿试点区）不同门类典型优势种，通过室内模拟，从生理学角度探讨各门藻体对短期与长期酸雨胁迫的响应与适应机制，并通过室内外竞争模拟实验进一步阐明酸胁迫对不同门类浮游植物竞争优势的影响，为揭示酸雨调控浮游植物群落结构变动及其演替趋势提供基础数据，并尝试为流域生态安全、水生态保护提供建议。

我国多数城市为酸雨频发区，酸雨已经成为我国较为严重的环境问题之一。黄山市作为世界文明的生态旅游城市，是安徽省受酸雨危害最大的城市之一，为我国主要的酸雨控制区。新安江是国内首个跨省流域生态补偿试点区，研究水体浮游植物群落结构及生理生态变化与流域内重要环境因子间的关系具有重要生态学意义。针对“酸雨调控浮游植物群落变动的生理生态机制”这一科学问题，对新安江流域浮游植物原位群落开展了模拟短期瞬时酸胁迫研究，结果表明短期模拟酸胁迫可显著改变浮游植物群落结构、降低浮游植物丰度以及多样性，不同门类、属种的浮游植物对酸胁迫的耐受能力具有显著差异。通过室外实验进一步探讨了原位水体浮游藻类群落结构组成在不同季节降雨前、降雨中以及降雨后的演替规律，结果表明降雨过程引起的水体pH值变动可显著调节浮游植物群落结构组成，其他环境因子（水体温度、阳光辐射强度以及营养盐等）可协同对浮游植物种属数、丰度及优势藻类产生影响。在此基础上，我们进一步开展了室内模拟实验，通过对不同门类典型藻体开展瞬时短期酸胁迫以及长期酸胁迫研究，探讨了短期与长期模拟酸胁迫对典型藻类光合生理、生化过程影响的异同，结果表明不同门类或同一门类相同属的不同种类，光合能力及光系统II电子传递过程间都存在显著差别，不同藻体对pH 值变动的耐受范围、耐受能力的差异性表现可能与藻体粒径大小、细胞酸碱调节能力、光系统电子传递过程以及抗氧化酶活性等有关。结合室内、外实验获得的各项生理生化指标，初步获得了酸雨引起的酸胁迫对不同门类浮游植物影响的光合生理机制，有关酸雨胁迫下种间竞争的研究仍在进行中，我们会在未来1-2年后续的进展报告中体现相关研究成果。在此期间，我们已发表本课题资助的论文7篇（其中SCI4篇，CSCD核心期刊3篇），获批发明专利1项、实用新型专利2项。