粒径小于3μm的超微型浮游藻类是水生生态系统的重要组成部分，由于受其个体微小和传统研究方法的限制，目前对于淡水超微藻的认知还非常有限。我们的初步调查结果表明超微藻在非水华期间对巢湖初级生产力的平均贡献达到了50%以上，并且其群落结构存在显著的时空差异。结合流式细胞分选和高通量测序的结果表明巢湖超微藻细胞上存在着大量的壶菌门真菌，并且两者之间可能存在特异性关系。壶菌门真菌是大型浮游藻类常见的寄生真菌，但其与超微藻寄生关系的相关研究还很少。寄生真菌可能对超微藻的生理生态特性和群落结构演替有重要的影响。本研究拟结合野外调查和室内培养实验，调查巢湖超微型浮游藻类及其寄生真菌群落结构的时空分布特征及关键影响因子，确定寄生真菌影响巢湖超微藻群落结构演替的关键时机；揭示超微藻和寄生真菌之间基于种间水平和遗传多样性分类水平的特异性关系；阐明寄生真菌对宿主超微藻的寄生感染作用机制。

Picophytoplankton, with the cell size less than 3 μm, is an important component in water ecosystems. Our knowledge about this tiny phytoplankton is still limited because of the shortage of the traditional research method due to its small size. Our preliminary results showed that picophytoplankton contributed to more than 50% of total primary production in Lake Chao during the non-bloom period. Meanwhile, the community structure of picophytoplankton showed temporal-spatial variation. Analysis results based on the flow cytometric sorting and high-throughout sequencing, indicated that picophytoplankton is attached with a large amount of fungi, which belong to Chytridiomycota. Furthermore, the zoospore of fungi might specifically attach to particular host picophytoplankton. Chytridiomycota has been found to be the common parasitic fungi on large phytoplankton, but little research reported the host-parasite relationship between picophytoplankton and fungi. Thus, we hypothesized that parasitic fungi may have an important impact on the physiological and ecological traits of picophytoplankton, as well as its community succession. In this study we will perform field investigation to explore the temporal-spatial distribution of picophytoplankton community and their parasitic fungi in Lake Chaohu, and their vital impact factors. The timing of when parasitic fungi impacts picophytoplankton community succession in the field will be determined. The specific relationship between the host picophytoplankton and parasitic fungi on the species level or on the operational taxonomy unit level will be determined. Laboratory incubation experiment will be carried out to explore the parasitic mechanism of fungi on their host picophytoplankton.