甬江干流浮游动物群落结构季节动态与水环境的关系

对采自2011年3月-2012年2月间甬江干流13个断面的水样, 按照国家标准测试了9项理化指标, 并应用浮游动物定性和定量方法, 研究了浮游物群落结构特点和季节变化. 研究共记录浮游动物95种, 其中轮虫24属72种、枝角类5属10种、桡足类11属13种和4种其他门类无脊椎动物幼虫; 优势种主要来自于轮虫动物的臂尾轮虫属(Brachionus)和龟甲轮虫属(Keratella), 前者占了浮游动物总丰度的22.1%, 后者占总丰度的20.2%. 浮游动物的丰度值在各断面均呈明显的季节变化, 从断面1至断面6, 最大峰值出现在春季, 从断面7至断面13, 最大峰值多出现在夏季; 全干流最大峰值出现在断面5 (3160 ind./L). 浮游动物群落生物多样性指数呈上游段低, 中、下游河段高的现象; 应用中度干扰假说(Intermediate disturbance hypothesis)对此结果给予了解释. Two-way ANOSIM相似性分析和Bray-Curtis相似性等级聚类分析显示: 不同断面上不同季节的浮游动物群落间均存在显著差异, 分别为R=0.264、P=0.1%和R=0.234、P=0.1%, 且季节性差异大于断面间差异. 在季节性差异中以春季和夏季间的差异性最大. 主成分分析(PCA)表明: 对不同断面浮游动物群落起作用的理化因子依次为CODCr、TN、DO和BOD5; 对不同季节浮游动物群落起作用的理化因子依次为pH、TN/TP、盐度和水温.  

Seasonal change of zooplankton communities and its relationship with aquatic environments in the Yongjiang River,Ningbo

In this study, water samples were collected from 13 sections in the Yongjiang River from March 2011 to February 2012. Physical and chemical factors were analyzed according to national standards. The structure characteristic and the seasonal changes of the zooplankton communities were measured by the qualitative and quantitative methods. 95 species in water samples were recorded. Among them, 24 genera and 72 species of Rotifera, 5 genera and 10 species of Cladocera, 11 genera and 13 species of Copepoda, and 4 other categories of invertebrate larvae were identified. The dominant species were Brachionus and Keratella, and the abundances of them in the total zooplankton were 22.1% and 20.2%, respectively. The abundance of zooplankton in each section showed a significant seasonal variation. From Section 1 to 6, the abundance peaks appeared in spring, and from Section 7 to 13, the peaks were presented in summer. The maximum peak of zooplankton abundance appeared in Section 5 (3160 ind./L). The biodiversity indexes of zooplanktonic communities were lower in the upstream sections compared with those of mid-downstream sections. The intermediate disturbance hypothesis was used to explain the results. The two-way ANOSIM analysis and Bray-Curtis similarities on hierarchical clustering analysis were used to analyze the similarities of zooplanktonic communities in the river. The results revealed that there were significant difference among the sections (R=0.264, P=0.1%) and seasons (R=0.234, P=0.1%), and the difference among seasons were more significant than the difference among sections. The maximum seasonal difference of zooplanktonic communities was presented between spring and summer. Principal component analysis (PCA) showed that in different sections the zooplanktonic communities were affected by CODCr mainly, followed by TN, DO and BOD5; when the seasonal changes were considered, the zooplanktonic communities were affected by PH mainly, followed by TN/TP, salinity and temperature.