Abstract: Species diversity and community structure of ciliates in the Pb-Zn-Contaminated section of the Shuiyangjiang River were studied during the period from October 2006 to May 2008,using water samples collected from 4 sampling sites in that section in 3 different periods.In the water samples,52 species of ciliates,sorted into 3 classes,12 orders,29 family and 33 genus,were identified,based on which water quality of that section of the Shuiyangjiang River was preliminarily evaluated.Results show that pollution of the water varied in degree between the four sampling sites in the section,following a decreasing order of Xiancheng>Changqu>Muba>Duizhao,from severe to moderate.Ciliates of Cyclidium citrullus,Paramecium caudatum,and Litonotus lamella were screened out to be indicators of Pb-Zn-contamination of water bodies.

Key words: the Shuiyangjiang River, Pb, Zn, ciliates, community characteristic, water quality assessment