长江荆江段浮游生物群落结构特征及其与环境因子的关系

为了解长江荆江段浮游生物的群落结构特征以及其与环境因子之间的关系，于2017年3、6、9和12月对荆江7个采样断面的左右岸共14个采样点的浮游生物群落结构及水文、水质参数进行了调查。结果表明：荆江采集到浮游植物7门67属135种(含变种)，以硅藻门（51.85%）和绿藻门（25.19%）为主。浮游植物的丰度均值为73.16×10 4 cells./L，生物量均值为0.87 mg/L，上荆江各采样断面间浮游植物丰度和生物量变化不明显，下荆江浮游植物的丰度和生物量表现从上游到下游逐渐增高的趋势。优势种为硅藻门的颗粒沟链藻和梅尼小环藻。Margalef 丰富度指数是0.83，Pielou均匀度指数是0.80和Shannon-Wiener多样性指数是1.90，下荆江的丰富度指数和多样性指数大于上荆江，说明上荆江比下荆江污染严重。典范对应分析溶氧、温度、氨氮是影响浮游植物群落结构的主要因素。浮游动物48属81种，其中轮虫最多（37.04%），其次是原生动物（25.93%）和枝角类（23.46%）。浮游动物丰度均值为6.32 ind./L，生物量均值为88×10-3 mg/L，上荆江浮游动物丰度和生物量低于下荆江。浮游动物优势种为冠砂壳虫、桡足类无节幼体和剑水蚤一种。Margalef 丰富度指数是5.2，Pielou均匀度指数是0.84和Shannon-Wiener多样性指数是1.32，下荆江的丰富度指数、均匀度指数和多样性指数均大于上荆江，说明上荆江比下荆江污染严重。冗余分析显示温度、溶氧和氨氮是影响浮游动物群落结构的主要因素。

Characteristics of Plankton Community and Its Relationships with Environmental Factors in the Jingjiang Reach of the Yangtze River

Four investigations were conducted at the 14 sampling sites in 7 sampling sections in the Jingjiang reach of the Yangtze River in March, June，September and December 2017 respectively to evaluate the relationship between plankton community composition and environmental factors. The results showed that 135 species (including varieties) of phytoplankton belonging to 7 phyla 67 genera were identified, dominated by Bacillariophyta (51.85%) and Chlorophyta (25.19%).The mean density and biomass of phytoplankton were 73.16×104 cells /L and 0.87 mg/L respectively. The difference of phytoplankton abundance and biomass among different sampling sections of upper Jingjian were not obvious, and the abundance and biomass of phytoplankton showed a steady increasing trend from the upper reaches to the lower reaches of lower Jingjiang. The dominant species were Aulacoseria granulate and Cyclotella meneghinian. Margalef richness index, Pielou evenness index and Shannon-Wiener diversity index were 0.83, 0.80 and 1.90 respectively. The richness index and diversity index of the Lower Jingjiang were higher than those of the Upper Jingjiang, which indicated that the pollution of the Upper Jingjiangwas more serious than that of the Lower Jingjiang. Canonical correspondence analysis showed that dissolved oxygen, water temperature and NH3-N were the main factors affecting phytoplankton community structure. A total of 81 species of zooplankton belonging to 48 genera were identified, dominated by Rotifer (37.04%). The mean density and biomass were 6.32 ind./L and 88×10-3 mg/L respectively, and the abundance and biomass of zooplankton in upper Jingjiang were lower than that in lower Jingjiang. The dominant species were Difflugia corona, Copepods nauplii and Cyclops sp. The richness index, evenness index and diversity index of the Lower Jingjiang are higher than those of the Upper Jingjiang, which indicated that the pollution of the Upper Jingjiang is more serious than that of the Lower Jingjiang. Canonical correspondence analysis showed that water temperature， dissolved oxygen and NH3-N were the main factors affecting zooplankton community structure.