鄱阳湖浮游动物群落结构及其与环境因子的关系

数量庞大、体积微小、高度多样化的浮游生物对淡水生态系统功能具有重要影响。为探究中国第一大淡水湖——鄱阳湖浮游动物（包括轮虫、枝角类和桡足类）群落特征及其与环境因子之间的关系，本研究在鄱阳湖设置50个采样点，分别于2017年8月（夏季）、11月（秋季）、2018年2月（冬季）和5月（春季）进行浮游动物群落与生境调查，统计分析结果表明：鄱阳湖浮游动物共记录43属99种，其中轮虫31属83种，枝角类8属11种，桡足类4属5种，春夏季节种类较为丰富。浮游动物平均丰度为1155.29 ind./L，具有极显著的季节差异（P< 0.01），夏季（3150.37 ind./L）显著高于其他三季。四季共确定优势种14种，轮虫中优势度最高的为广布多肢轮虫（Polyarthra vulgaris），浮游甲壳动物中仅有简弧象鼻溞（Bosmina coregoni）在秋季形成优势。优势种的季节更替明显，夏秋季节间的更替率（86.00%）高于其他季节（77.00%，66.67%）。优势种、多样性和均匀度的结果均显示鄱阳湖浮游动物群落结构较复杂，具有较好的稳定性。聚类分析（Cluster analysis）和分类回归树分析（Classification and regression trees, CART）表明，每个季节均有多种群落类型，其中春夏两季中浮游动物群落类型的划分与叶绿素a（Chlorophyll a，Chla）密切相关，化学需氧量（Chemical Oxygen Demand，COD）是影响秋季群落划分的关键环境因子。非度量多维尺度分析（Non-metric multidimensional scaling，NMDS）结果表明，温度（Water Temperature，WT）、Chla、电导率（Conductivity，Cond）是造成四季浮游动物群落显著差异的最主要环境因子。冗余分析（Redundancy analysis，RDA）显示，除Chla外，总氮（Total Nitrogen，TN）、总固体悬浮物（Total Suspended Solids，TSS）和酸碱度（Hydrogen ion concentration，pH）也是影响浮游动物群落结构和优势种分布的重要因素。

Zooplankton community structure and its relationship with environmental factors in Poyang Lake

Plankton, with large quantity, small size and high diversity, have an important impact on the function of freshwater ecosystem. To explore the community characteristics of zooplankton (including rotifers, cladocerans and copepods) in Poyang Lake, the largest freshwater lake in China, and their relationships with environmental factors, 50 sample sites were set up in Poyang Lake. Zooplankton community and environmental survey were conducted in August (Summer) and November (Autumn) in 2017, February (Winter) and May (Spring) in 2018, respectively. The statistical results showed that 99 taxa belonging to 43 genera were identified, of which 83 species in Rotifera belonged to 31 genera, 11 species in Cladocera belonged to 8 genera, and 5 species in Copepoda belonged to 4 genera. Species were abundant in spring and summer. Zooplankton abundance in four seasons were significantly different with a mean abundance of 1155.29 ind./L. Zooplankton abundance in summer (3150.37 ind. / L) was significantly higher than that in other seasons. A total of 14 dominant species were identified in all seasons. The most dominant species in rotifers was Polyarthra vulgaris, and Bosmina coregoni in crustaceans was dominant only in autumn. The dominant species obviously shifted among seasons and the seasonal turnover rate from summer to autumn (86.00%) was higher than that in other seasons (77.00%, 66.67%). The results of dominant species composition, diversity and evenness indexes suggested that zooplankton community structure in Poyang Lake was complex and stable. Cluster analysis and classification and regression trees (CART) showed that there were several community types in each season, among which the division of zooplankton community types in both spring and summer was closely related to Chla, and chemical oxygen demand (COD) was the key factor affecting community division in autumn. Non-metric multidimensional scaling (NMDS) and redundancy analysis (RDA) indicated that Water temperature (WT), Chla, Conductivity(Cond) were main factors related to significant differences in zooplankton communities among seasons. Redundancy analysis (RDA) showed that Total Nitrogen(TN), Total Suspended Solids(TSS) and pH were also important factors affecting zooplankton community structure and distribution of dominant species.