中文摘要：

2014年夏季对鄱阳湖进行采样调查,以探究超微型浮游植物在鄱阳湖中的空间分布特征及其与环境因子的关系.结果表明,丰水期鄱阳湖超微型浮游植物细胞丰度较高,平均值为1.04×108cells/L,超微蓝藻是超微型浮游植物的优势种群,尤其在北部通江湖区,占总超微藻丰度的比例超过80%.超微藻对总浮游植物净初级生产力和生物量（以叶绿素a浓度表示）贡献率的均值分别为44%和46%.鄱阳湖超微藻在空间分布上存在差异,超微藻丰度和叶绿素a浓度在南部湖区最高,其次是北部湖区,在东部和中部湖区相对较低.北部湖区超微藻对总浮游植物净初级生产力和生物量的贡献率全湖最高,分别能达到60%和50%.相关性分析表明,营养盐对超微型浮游植物生长的作用表现不明显,超微藻对总浮游植物净初级生产力的贡献率与水体透明度呈极显著负相关,水体p H值对超微真核藻丰度有显著影响.

英文摘要：

35 sampling sites were carried out in the summer of 2014 in Lake Poyang, to explore the spatial distribution characteris- tics of picophytoplankton during the wet season. The cell abundances of two groups of picophytoplanktou were obtained （ photosyn- thetic picoeukaryotes with rich chlorophyll-a and picocyanobacteria with abundant phycocyanin） by flow cytometric analysis direct- ly, which was performed with a FACSJazz flow cytometer unit, while the hetertrophic nanoflagellate should be pre-stained by SYBR Green I dye. In addition, the relationships between the abundance, biomass and net primary production （NPP） of picophytoplank- ton and the related environmental factors were also considered. Our results showed that, cell abundance of picophytoplankton in Lake Poyang was high, and its average value could reach to 1.04× 108cells/L. Picocyanobacteria dominated picophytoplankton in abundance, especially in the north region of the lake （which connected with Yangtze River）, where the proportion of cell abun- dance between picocyanobacteria and picophytoplankton was more than 80%. The average contribution of picophytoplankton to the NPP and biomass of total phytoplankton could reach to 44% and 46%, respectively. The distribution of picophytoplankton showed spatial variation in Lake Poyang. The abundance and chlorophyll-a concentration of picophytoplankton were the highest in the south region, followed by the north region, and were relatively low in the middle and the east regions. The contribution of picophyto- plankton to NPP and biomass of total phytoplankton achieved the highest in the north lake area, reaching to 60% and 50%, re- spectively. The correlation analysis results showed that the effect of nutrients on picophytoplankton growth was not obvious in Lake Poyang during the wet season. The contribution of picophytoplankton to the NPP of total phytoplankton was negatively related to wa- ter transparency. The abundance of picocyanobacteria was significantly affected by water temperature and the dens