乌江主要支流夏季底栖动物群落组成及其与汞污染的相关性

对贵州省境内乌江流域的16条主要支流进行了底栖动物调查，共获底栖动物78种，分别隶属于4门7纲17目39科，密度为22～21 712 m-2. 瓮安河及其下游各支流底栖动物的种类和数量较丰富，上游各支流的种类和数量则较少. 从群落相似性看，上游支流以节肢动物占优势，群落组成较相似，中下游支流以软体动物占优势，群落组成差别较大. 以HAKANSON的潜在生态危害系数法进行评价，结果表明，流域中底泥汞生态危害程度表现为轻微、中等或强度危害. 底栖动物物种数和密度与底泥汞的潜在生态危害系数均呈负相关关系，但相关性不显著(R分别为-0.32和-0.12，P＞0.01)，因此，流域汞污染对底栖动物的影响还有待进一步研究. 

Zoobenthic Community Structure and Its Correlation with Mercury Pollution in Main Tributaries of Wujiang River in Summer

After investigating the zoobenthic community in 16 main tributaries of the Wujiang River, Guizhou Province, 78 species were obtained, belonging to 4 phyla, 7 classes, 17 orders and 39 families, with 22-21,712 individuals per square meter. Species compositions and individual numbers of zoobenthos in the Weng’an River and its downstream tributaries were more abundant than those in the upstream tributaries. Studies on community similarity showed that while arthropods were dominant in the upper tributaries, mollusks were dominant in the middle and lower tributaries. Community structures were similar among the upper tributaries, but were quite different among the middle and lower tributaries. Assessment of potential ecological risk caused by mercury in the sediments was conducted according to Hakanson’s method, and the results demonstrated that the risk degrees were from slight to heavy levels in the river valley. Negative and no significant correlations were found between Hg Potential Ecological Risk Index and species number and density of zoobenthos (R-0.32, -0.12， P＞0.01); therefore, the effect of mercury pollution on zoobenthos in the river valley should be further investigated.