基于附石藻类生物完整性指数对汝溪河水生态系统健康的评价

以三峡库区支流-汝溪河自然河段为研究区域，调查了自然河段内9个样点的附石藻类群落和水环境理化特征，并在此基础上应用生物完整性评价指数（Index of Biotic Integrity，IBI），对汝溪河水生态系统进行健康评价。结果表明，汝溪河自然河段附石藻类群落结构具有明显的空间和时间异质性，驱动附石藻类群落结构形成的水环境因子为电导率、浊度、硝态氮和溶解氧。IBI结果表明，上游生物完整性较高；中下游和下游生物完整性较差；枯水期生物完整性较高，而平水期和丰水期生物完整性较低。由此可见，汝溪河自然河段生物完整性一般，表明汝溪河水生态系统已处于亚健康程度。

USING EPILITHIC ALGAE ASSEMBLAGES TO ASSESS STREAM HEATH OF THE RUXI RIVER,CHINA

The present study investigated the community structure of epilithic algae and characteristics of environmen-tal factors among 9 sample sites in Ruxi River, a tributary of the Three Gorges Reservoir. The health of freshwater eco-system in the stream conditions of Ruxi River was assessed via Index of Biological Integrity (IBI). The results indi-cated that there were significant spatial and temporal differences in the epilithic algae community structure in Ruxi River and conductivity, dissolved oxygen, nitrate nitrogen and turbidity were the major environmental factors in Ruxi River. IBI result showed that the upstream area of Ruxi River were in excellent biological integrity, while the mid-stream and downstream area were in severe impairment. The biological integrity in dry season was preferable to the normal. Thus, the biological integrity in natural stream of Ruxi River showed a general level, suggesting that a sub-health aquatic ecosystem was found in Ruxi River.