长江流域鄂西四河流大型底栖动物群落结构特征及水质生物学评价

鄂西水系是国家级水源保护区，也是湖北省重要的生态旅游区。为了解鄂西水生态健康状况，于2014年10月~2017年1月不同时段在宜昌国家可持续发展实验示范区卷桥河（J）、清江利川段（Q）、宜昌市水源地黄柏河（H）和丹江口入库河流天河郧西段（T）开展了底栖动物群落特征研究。研究表明：4个河段共采集到大型底栖动物5门8纲18目61科。基于底栖动物指示种耐污性及其丰度占比分析，表明J、Q和T三河流污染程度沿水流方向呈加重趋势，而H水体健康状况整体较好。运用FBI和SIGNAL底栖生物评价指数，显示四条河流健康程度沿水流方向均呈下降趋势，但H变化趋势平缓，结果表明H水体上下游均处于较健康状态，其他3条河流上游或源头水体健康状况良好，下游受到较重污染。对主要环境因子（TP、NH₃-N、COD_Mn和TN）做主成分分析表明，轴1的解释率达到65.1%，表明轴1可以有效表征主要环境压力梯度。FBI和SIGNAL指数与轴1线性拟合度均较高，表明二者在鄂西河流水生态健康评估中可作为快速生物评价指数。

Macrozoobenthic Community Structure and Water Quality Bioassessment of Four Rivers in Western Hubei Province,Yangtze River Basin

The western Hubei province is a national water source protection zone and important ecotourism areas. To understand ecological health status of river ecosystem, a field survey on the macrozoobenthic community structure and water quality bioassessment was carried out in Juanqiao river (J), Lichuan reach of Qingjiang river (Q), Huangbo river (H) and Yunxi reach of Tianhe (T) from October 2014 to January 2017. A total of 61 families were observed in four rivers, including 5 phyla, 8 classes, and 18 orders. Leptophlebiidae, Atyoidae and subfamily Chironominae are the dominant group in J1, J2 and J3 sites, respectively. Heptageniidae accounts for 55.0% of total abundance caught in Q1, and Corbiculidae for 83.8% and 64.8% in Q2 and Q3, respectively; Viviparidae is the most dominated group in Q4 while strong tolerance Tubifex occurred. Tubifex and subfamily Chironominae account for 49.5% in Q5. Tolerance sensibility along water flow direction was decreased in J, Q and T rivers, indicating water quality degradation. However, all seven sampling sites were dominated by the sensibility macrozoobenthic group in H River, indicating a good water quality. The analysis of environmental variance with the principal components analysis showed the first axis could represent pollution gradient with 65.1% explanation．The linear regression analysis results further revealed a significant relationship between FBI and SIGNAL indices and the first axis. The correlations between both indices were significant which showed consistent results in river health assessment. The results indicate FBI and SIGNAL index are suitable for river health assessment in Western Hubei Province.