入侵种小龙虾对鄱阳湖沉水植物群落的影响及其机制

入侵种小龙虾对长江中下游湖泊水体生态系统安全的影响正在日益加剧。沉水植物群落是维持淡水、浅水、草型湖泊生态系统结构与功能稳定的最重要初级生产力，也是湖泊生态系统食物网必不可少的环节。但是，关于小龙虾对沉水植物群落影响的过程和机制尚不清楚。本研究选取小龙虾数量巨大、沉水植物群落正处于退化过程、富营养化趋势明显的鄱阳湖为研究地点，综合运用野外调查、受控实验以及胃容物镜检和宏条形码等方法，研究小龙虾的食性及对沉水植物的牧食偏好、小龙虾种群密度对沉水植物生长的影响、不同营养条件下小龙虾对沉水植物群落结构与功能的影响。旨在采用全新的方法深入解析鄱阳湖小龙虾的食性，阐明沉水植物对小龙虾牧食的反应变化规律，探讨不同程度富营养化对小龙虾-沉水植物生态关系的影响。有助于进一步揭示水生动物与水生植物之间的相互作用关系，客观评价入侵种的生物/生态学影响，为湖泊生态系统自然恢复和可持续利用的人为调控提供科学依据。

The impact of invasive species Procambarus clarkii on the security of lake ecosystems along the middle-lower reaches of the Yangtze River is growing intensively. Submerged macrophyte communities are important for maintaining structural and functional stability in freshwater, shallow and submerged macrophyte-dominant lake ecosystems, and play an essential role in the aquatic food web. However, the process and mechanism of crayfish affecting submerged macrophyte communities remain unclear. In this study, we select Poyang Lake as study site, which has a huge number of crayfish, and exhibits an on-going degradation of submerged macrophyte communities and an apparent tendency of lake eutrophication. We integrate field investigation, controlled experiments, as well as microscopic examination of stomach contents and DNA metabarcoding to explore seasonal variation in diets of crayfish and herbivory selectivity on submerged macrophytes; 2) investigate effects of crayfish population density on the growth of submerged macrophytes; 3) examine the effects of crayfish herbivory on structure and function of submerged macrophyte communities under contrasting water nutritional conditions. Our study aims to fully understand diet compositions of crayfish, elucidate the responses of submerged macrophytes to crayfish herbivory, and estimate the effects of different eutrophication levels on the ecological relationship between crayfish and submerged macrophytes. Our study would contribute to revealing the interaction between aquatic animals and aquatics, providing objective estimation of the biological/ecological effects of invasive species, and providing scientific basis for natural restoration of lake ecosystems and their sustainable utilization by means of artificial regulation.