凤眼莲大规模圈养条件下滇池蓝藻化感作用变化及其生态效应研究

Allelopathic effects of cyanobacteria on other aquatic organisms is one of the reasons why it can survive and dominant in the eutriphic shallow lakes. Envoronmental stress, such as compitition with higher plants and green algae,or preyed by fishes, would chang the chemical relationship between cyanobactria and other living things..Water hyacinth (Eichhornia crassipes) have been used widely in Dianchi Lake since 2011, due to its high abilities of pollutions abstraction and harmful algae inhibition. We have a hypothesis: water hyacinth would increace the allelopathy of cyanobacteria on other water organisms and enhance its harmness to water ecosystem. But we don't know the details about the allelopathic chemicals and the injuring mechanisms. In this project, we designed some experiments to study wether and how Microcystic aeruginosa would affect the growth of submerged microphytes, green algae and diatom in Dianchi Lake, using in situ investigation and laboratory experiments. After isolation and selection of allelopathic compounds from Microcystic aeruginosa and water hyacinth, we will check the physiological and molecular mechanisms of their inhibition on receptors. The influence of water hyacinth allelopathic substances on this chemical relationship will be determined by adding them to algae mediums.The study will elucidate the effects and ecological results of large-scale water hyacinth planting in eutrophic lakes and the ways to avoid the unpleasant problems.

化感效应是富营养化水体蓝藻水华形成和维持的重要机制之一，而环境胁迫能诱导蓝藻加速释放化感物质以获取竞争优势。凤眼莲因污染物净化及抑藻能力强等优点而正被大规模用于滇池等富藻水体的生态治理，我们推测其对蓝藻的化感胁迫会改变蓝藻与其它水生生物间的化学生态关系，但其物质基础、生理机制及影响因子尚不清楚。本项目以滇池为例，采用野外调查和实验室模拟相结合的方法，研究铜绿微囊藻分泌物对滇池常见的沉水植物、绿藻及硅藻的化感效应及其种间差异；筛选凤眼莲对蓝藻的关键抑藻物质；重点研究添加凤眼莲抑藻物质如何改变蓝藻对前述沉水植物和浮游植物的化感效应，探讨其关键活性物质、对受体生物的生理及分子抑制机理，明确凤眼莲大规模圈养对滇池等富藻水体蓝藻化感作用的影响及其生态效应。研究成果在理论上有助于揭示凤眼莲存在下蓝藻与其它水生生物间的化学生态关系及其生态后果，在实践上能为滇池流域凤眼莲及沉水植物的合理种养提供指导。

化感效应是富营养化水体蓝藻水华形成和维持的重要机制之一，而环境胁迫能诱导蓝藻加速释放化感物质以获取竞争优势。为揭示水华蓝藻对水生生物的化感效应及该类“化学武器”在滇池蓝藻水华形成和维持机制中的作用及其机理，同时探讨凤眼莲抑藻物质及其它环境污因子对该化学生态关系的影响及其生态效应和分子机理。本项目研究了世界范围内广泛分布的水华蓝藻优势种——铜绿微囊藻分泌物对滇池常见的沉水植物、绿藻及硅藻、土著鱼类胚胎的化感效应及其种间差异和分子机制；通过凤眼莲关键抑藻物质添加法等探讨了环境胁迫条件下蓝藻化感效应的变化及其后续生态效应；同时分离纯化了蓝藻分泌物中的主要化感物质。结果表明：（1）铜绿微囊藻对滇池常见沉水植物及其它浮游植物具有显著化感抑制作用，且胞外分泌物的活性显著高于胞内提取物；（2）对数生长期是蓝藻释放化感物质的主要阶段，而衰亡期分泌物则具有明显的促进作用；（3）凤眼莲化感物质N-苯基-2-萘胺及水体新兴有机污染物能强化蓝藻的化感效应；（4）蓝藻胞外分泌物对滇池金线鲃胚胎具有十分显著的致畸作用，其中与胸腔畸形有关的蛋白组表达异常。这些研究成果揭示了蓝藻的化感效应能普遍作用于水生生态系统中的关键组分，从而导致广泛的不良生态效应。本研究为揭示蓝藻与其它水生生物间的化学生态关系及其影响因素、藻型富营养化水生生态系统的生态风险防控提供了重要的参考依据。