AN EVALUATION ON POLLUTION IN THE XIANG JIANG RIVER BY USING ZOOBENTHOS

Studies on zoobenthos in the Xiang Jiang River were carried out for five times between July, 1980 and December, 1981. Artificial substrate was used for sampling in all stations in the river, especially the heavily polluted area between Zhuzhou and Xiangtan.Based on the data obtained from the survey, Shannon diversity index was calculatedand used for the biological evaluation of water quality of the river. Relationship between the number of zoobenthos and the chemical content was also calculated in some stations.Results show that the mayfly naiads are more sensitive to heavy metals and pesticides.They may be used as monitors for water pollution in the river. The percentage of ephemeropterans and trichopterans as compared with that of the other aquatic insects used for water monitoring is also given in this paper.Nearly in all stations the diversity indices were more than 2.11, except the Xiawan station, where the index was only 0—0.73.