汉江中下游春季浮游甲壳动物群落结构的空间差异

SPATIAL VARIATIONS OF PLANKTONIC CRUSTACEA COMMUNITIES IN THE MIDDLE AND LOWER HANJIANG RIVER

2002年4月,在汉江中下游从丹江口坝上至其河口沿途设17个采样点,共采集到浮游甲壳动物10科26属33种,其中桡足类4科10属11种,枝角类6科16属22种。根据各采样点的种类组成和数量分布,采用Shannon Wiener指数、Simpson指数和Pielou均匀度指数分析了不同江段浮游甲壳动物的群落多样性特征,并运用SOM人工神经网络方法对其群落结构的空间差异进行了比较。结果表明,汉江中下游江段浮游甲壳动物的密度分布呈现出中游高于下游的特征,而物种丰度和群落多样性指数则是下游高于中游;中游上段的属于密度高但多样性低的群落、中游下段和汉江口属于密度较低但多样性高的群落,下游除汉江口外属于密度和多样性均较低的群落。

In April 2002, 33 species of planktonic crustacea in 26 genera (11 Copepoda and 22 Cladocera) were sampled from 17 sites in the middle and lower reaches of the Hanjiang River, the largest tributary in the middle reaches of the Yangtze River. Shannon-Wiener, Simpson, and Pielou indexes calculated from species composition and abundance were used for evaluating the community diversity characteristics in different reaches. Spatial variations of the communities in different reaches were compared by method of Self-Organizing Map (SOM) artificial neuronal networks. The results were summarized as followings: (a) the density of planktonic crustacea in middle reach was higher than that in the lower reach whereas the species abundance and community diversity index in the lower reach were higher than that in the middle reach; (b) the planktonic crustacea communities presented high density but lower diversity in the upper part of the middle reach, lower density but high diversity in the lower part of the middle reach and estuary, and lower density and diversity in the lower reach except the estuary.