中文摘要：

2013年9月份龙江流域设20个采样点,共鉴定出硅藻30属163种。硅藻群落特征分析表明,上游河段的硅藻相对密度比下游河段的大,水质相对较好,硅藻种类数的变化与河流水质的变化没表现出明显的规律性。RDA分析表明8个环境因子共解释了硅藻群落变异的51.3%,并筛选出溶解氧、温度、电导率和海拔为影响硅藻群落变异和空间分布的显著因子,能解释硅藻群落结构变异的30.9%,占总环境因子解释量的60.23%。硅藻相对密度、硅藻种类数与环境因子的相关分析、聚类分析和回归分析表明,硅藻种类数与环境因子间不存在明显的相关关系,而硅藻相对密度则与海拔存在显著的相关关系。

英文摘要：

In September 2013, diatom assemblages were collected from 20 sites in Longjiang River Basin. Altogether 30 genera and 163 species were identified. Community characteristics of diatom analysis showed that the diatom relative density of upper reaches was greater than the downstream, and the water quality was relatively good, changes in water quality and the number of species showed no obvious regularity. RDA analysis showed that eight environmental factors explained 51.3% of the variation in the diatom community, and filter out dissolved oxygen, temperature, conductivity and altitude, as several significant factors which influence the community variability and spatial distribution of the diatoms, could explain 30.9% variation in the diatom community structure, accounting for 60.23% of the total amount of environmental factors. Diatoms relative density, the number of diatom species and environmental factors related to correlation analysis, cluster analysis and regression analysis showed that there is no significant correlation between the number of diatom species and environmental factors, but diatoms relative density with altitude there is a＇significant correlation.