沉水植物诱导绿藻群体形成机制研究

Submerged macrophytes, one of the most important primary producers in aquatic ecosystems, can obviously reduce the biomass of harmful algae(especially for Microcystis).This is of great value in holding the clear-water state of shallow lakes. Whereas in view of algal growth rate, biomass and photosynthetic activities, rare studies have showed the allelopathic inhibition effects of green algae by submerged plants. Furthermore, field survey indicated that in the presence of submerged macrophytes with high biodiversity, green algae are usually dominated. Our previous studies also suggested that submerged macrophytes might play important roles in promoting colony formation and maintaining dominance of green algae. So far, the morphological responses of green algae to plants and its related environmental factors are still not clear. Consequently, combined indoor experiments with field survey, following studies are mainly to be conducted: (1) Screen macrophyes that play roles in influencing green algae morphology, resorting to co-cultivation, filtrate and plant extract experiments. Demonstrate the physiological characteristics changes of green algae induced by submerged macrophytes; (2) Seperate and identify the allelopathic substances secreted by macrophytes utilizing multi-technique integrated methods. Detect the environmental factors in affecting substances secretion. (3) Conduct field study to verify the colony formation of green algae induced by submerged macrophytes and detect the ecological adaptation mechanisms of colonial green algae. Via these stuides, it’s aimed to rich the theoretical knowledge between plants-algae interactions and provide key scientific basis for shallow lake ecosystems restoration and water environment protection.

沉水植物作为水生态系统的重要初级生产者，能够显著降低有害蓝藻(尤其是微囊藻)生物量，对维持浅水湖泊清水状态具有重要意义。但从藻类生长率、生物量、光合活性角度，鲜有报道沉水植物对绿藻的化感抑制效应，且野外调查发现沉水植物丰富的水体，绿藻多占优势。项目申请者前期研究初步认为沉水植物在诱导绿藻群体形成、维持生物量和优势度方面扮演重要角色，但是关于绿藻形态对沉水植物响应机制及影响因子尚不清楚。据此，本研究拟通过室内模拟结合野外实验，开展以下工作：(1)采取共培养、种植水和沉水植物提取液培养，筛选对绿藻群体形成有影响的沉水植物并阐明沉水植物诱导下的绿藻生理特征响应；(2)多技术联用分离鉴定化感活性物质并探讨外源影响因子作用机理；(3)野外验证绿藻形态对沉水植物的响应并探讨群体绿藻生态学适应机制。通过本研究旨在丰富沉水植物与藻类间相互作用理论体系，为浅水湖泊水生态功能恢复和水环境保护提供重要科学依据。

沉水植物作为水生态系统的重要初级生产者，能够显著降低有害蓝藻生物量，对维持浅水湖泊清水状态具有重要意义。但从藻类生长率、生物量、光合活性角度鲜有报道沉水植物对绿藻的化感效应。本项目选择代表性沉水植物金鱼藻、篦齿眼子菜、菹草进行试验，开展了草-藻共培养、滤液、研磨液试验；摸索沉水植物金鱼藻活性物质分离提取方法，进行活性物质鉴定以及纯活性物质添加实验；以所在单位养殖池塘为研究对象，监测了蓝藻水华暴发期间，养殖池塘浮游藻类动态变化情况，并采用围格实验，探讨了金鱼藻、篦齿眼子菜对蓝藻暴发期间浮游藻类组成的影响。实验表明（1）金鱼藻能诱导小球藻群体形成，其诱导程度与添加金鱼藻生物量、试验小球藻密度有关。（2）本实验初步揭示了绿藻群体形成的生态意义，一方面沉水植物诱导小球藻群体形成，缓解了二者之间的竞争，促进了小球藻向水底沉降，这似乎不利于小球藻的生长，但是通过实验，我们认为群体形成是暂时的，而且一旦沉水植物胁迫解除，这些群体会转换成单细胞，伴随着生长率增加，可能群体外的胞外多糖起重要作用。（3）本研究探讨了金鱼藻丙酮、甲醇提取物成分，初步揭示棕榈酸、α—亚麻酸、硬脂酸在诱导小球藻群体形成方面扮演重要角色。本研究丰富了沉水植物与藻类间相互作用理论体系，揭示绿藻的生态适应性策略和沉水植物对藻类群落结构的调控机理，对浅水湖泊水生态功能恢复和水环境保护具有重要科学意义。