Xiangxi River was the biggest tributary of the Three Gorges Reservoir in Hubei Province, which had it length of 94km, a catchment area of 3,099km(2) and a natural fall of 1540m. Since June 1st, 2003 the segment of Xiangxi River front the river mouth to Xiakou had been formed the backwater region. In this region the spatial and temporal distribution of plankton rotifers were investigated at monthly intervals from July, 2003 to June, 2004. Among the 80 rotifer species identified, 13 species were predominant, which were Synchaeta sp., Keratella cochlearis, Polyarthra trigla, Conochilus unicorni, Trichocerea lophoessa, Trichocerca gracilis, Brachionus angularis, Keratella valga, Tirchocerca similes, Brachionas forficula, Brachionus Calyciflorus, Trichocerca porcellus and Pompholyx sulcata. A maximum density of 2459.23 ind. /L was observed in September and the minimum of rotifer density was found in December (85.00 ind. /L). ANOVA was used in the variance analysis of rotifer density in different months, the result was found that rotifer density, Margalef and Shannon-Wiener diversity index significantly different (n = 12, P < 0.01 so the temporal dynamic of rotifer density in Xiangxi Bay was obvious. At the same time, the spatial distribution of rotifers in this region was discussed. The highest density of rotifer was found in Site VI, the least density was found in Site IX. Rotifer density decreased along the water flow. And all the sites Could he divided into 4 groups by the cluster analysis, the first group was from Site I to V; the second group was Site VI; the third group was Site VII and VIII; and the fourth group was Site IX. Rotifer density was evidently positive correlation with temperature, hot negative correlation with water depth. The main factors regulating rotifer population were water temperature and food resource. Also in this article the relationship between rotifer and water quality was discussed.
Zhou Shu-Chan; Huang Xiang-Fei; Tang Tao; Cai Qing-Hua (qhcai@ihb.ac.cn).Primary studies on plankton rotiefers and water quality assessment in Xiangxi Bay of the Three Gorges Reservoir,Acta Hydrobiologica Sinica,2006,30(1):52-57
