椎实螺非经典生物操控法防治蓝藻水华的机理与应用研究

Non-classical biomanipulation, using fishes as manipulation species to ingest and to increase predation pressure against cyanobacteria, has been proved to be one of the effective means to control cyanobacteria bloom. Preliminary study found that, inoculation of Lymnaea spp. into the eutrophic water could effectively inhibit the cyanobacteria bloom. Because of its fast filtration, rapid reproduction, toxicity tolerance, the ability of living in the surface water, and other characteristics, Lymnaea spp. could be an ideal candidate to be used in non-classical bio-manipulation. But in the food web, its materials and energy transformation, as well as bio-manipulation mechanisms and efficiency, are not clear so far. This project intends to study the process of the predation, digestion, and assimilation of cyanobacteria by Lymnaea spp. using the microdissection techniques, and validate their relationship in the food web. The gastrointestinal microflora will be further examined by the function-guided microbial separation technology, to clarify the reason of cyanobacteria decomposition. The tolerance and degradation of algal toxins and odor compounds will be thereafter determined to elucidate the survival mechanism of Lymnaea spp. in cyanobacteria bloom. According to their respective population growth, we will quantify the efficiency of Lymnaea spp. against cyanobacteria and the response upon the increase of cyanobacterial loading. Together with the technique using floating plants absorbing N and P, the combined bio-manipulation method of Lymnaea spp. will also be attempted. Finally the field test of thus bio-manipulation and related control approaches for ecological safety will be conducted. This research not only provides new species and technology to be involved in non-classical bio-manipulation, but also deepens the knowledge and cognition of the food web structure and function in eutrophic water from the water ecological point of views.

非经典生物操控法利用鱼类等操控生物，捕食蓝藻，提高牧食压力，是治理蓝藻水华的有效手段。项目前期研究发现，富营养化水体中引入椎实螺，因其滤食效率高、繁殖快、耐毒性强、可贴水表生活等特点，可有效抑制蓝藻水华爆发。但其在食物网中的物质、能量中转作用及生物操控的机理、效率均不明确。本项目拟利用显微解剖技术，研究椎实螺对蓝藻的捕食、消化、吸收过程，验证二者在食物网中的关系；依靠功能微生物分离技术，研究椎实螺消化道菌群对蓝藻的分解作用；测定椎实螺对藻毒素、异味物质的耐受与分解，阐明椎实螺在水华爆发时的存活机制；根据各自的种群发育速度，量化椎实螺控制蓝藻的效率和对蓝藻负荷增大的响应效率；结合吸收N、P的水表植物，研究椎实螺联合控藻技术；最后进行生物操控的现场测试和生态安全控制。本项目研究成果不仅提供新型的非经典生物操控物种和技术，更可以从水体生态学角度加深对富营养化水体中食物网结构和功能的认识。

频繁爆发的蓝藻水华严重危害环境安全和人类健康。基于生物操控理论的生物控藻是通过调整生态系统食物网结构，达到防治蓝藻水华的目的。可避免化学法的二次污染和物理法的高成本弊端，具有成本低、安全的优势。非经典生物操控通过放养滤食性鱼类直接觅食蓝藻而达到生物操控目的。本项目提出了利用肺螺亚纲的椎实螺Lymnaea spp.作为新型的操控生物，用于控制蓝藻水华的发生。.项目验证了Lymnaea spp.对多种常见蓝藻品种的捕食、消化、杀灭作用，培育经Lymnaea spp.消化蓝藻后的粪便，未检出活的蓝藻细胞，Lymnaea spp.对于常见蓝藻品种有良好的捕食和消化作用。分离并研究了Lymnaea spp.共附生微生物对于蓝藻的影响，未发现具有控藻活性的微生物；但从Lymnaea spp.附生生物中发现了一种鞭毛虫，对蓝藻细胞有极强的破坏和杀灭作用。分析了Lymnaea spp.对于藻毒素等的耐受情况，发现Lymnaea spp.可存活于30μg/L的MC-LR和120μg/L总MCs条件下。Lymnaea spp. 防控蓝藻的量化研究发现1.25g/L的Lymnaea spp.投入量可以抑制约2×105 cell/ml的蓝藻增殖，在3天后无活蓝藻细胞检出。实验了Lymnaea spp.和其他生物对蓝藻的联合防控，Lymnaea spp.、EM菌（添加碳源Glu）、Lymnaea spp.+ L. perpusilla、Lymnaea spp.+ EM等处理方式可以有效控制蓝藻增殖。并且Lymnaea spp.+ L. perpusilla还可以显著降低水体的藻毒素水平和总毒性水平。通过养殖池塘模拟实验，验证了上述处理方式的有效性。.本项目基于非经典生物操控理论，从生态系统上游捕食者角度，验证了利用Lymnaea spp.等为操控生物可对水体蓝藻细胞增殖进行抑制调控，证明了Lymnaea spp.对藻毒素等蓝藻水华带来的有害物质的耐受和消减作用，建立了基于非经典生物操控理论并以Lymnaea spp.为主的多物种联合的高效控藻体系，可用于如养殖池塘等富营养化水体的蓝藻水华的生物防治，为蓝藻水华的生物防治提供了新的方法和思路。