浦阳江底栖动物群落特征与水质生物评价

Characteristics of benthic macroinvertebrate community and bioassessment of water quality in the Puyang River

调查了浦阳江流域26个样点的水体物理化学属性和大型底栖无脊椎动物群落结构,并采用Shannon-Wiener多样性指数和生物指数（BI）评价浦阳江水质.共获得4门7纲17目56科104属123个底栖动物分类单元,其中水生昆虫的物种丰富度和个体数均最高,细蜉属（Caenis）为第一优势种,集食者与中性类群的物种丰富度和个体数分别在功能摄食类群和耐污-敏感类群中最高.Shannon-Wiener多样性指数与化学需氧量（COD_（Cr））（r=-0.515,P=0.007）、总磷（TP）（r=-0.665,P=0.000）极显著负相关;BI与COD_（Cr）（r=0.406,P=0.040）显著正相关,与TP（r=0.704,P=0.000）极显著正相关.典范对应分析（CCA）结果表明,TP、Zn、COD_（Cr）、水温（WT）和p H是影响浦阳江流域底栖动物群落结构的主要环境变量,蜉蝣目和寡毛类是该地区环境变化的主要指示生物类群.Shannon-Wiener多样性指数和BI评价结果表明,浦阳江水体生态质量总体为轻污染或中污染,干流河段略优于支流河段,其中上游点位为清洁水平,少数重污染点位出现在中下游河段上.本研究表明水污染是决定浦阳江底栖动物群落组成和结构变化的重要环境问题因子,降低水体中TP和COD_（Cr）等污染物浓度将有助于浦阳江底栖动物群落的恢复.

Benthic macroinvertebrates and physicochemical variables were investigated across 26 sites in the Puyang River, Zhejiang, China in April 2016. Water quality was assessed by the Shannon-Wiener diversity index and biotic index（BI）. We collected a total of 123 macroinvertebrate taxa, belonging to 104 genera, 56 families, 17 orders, 7 classes, and 4 phyla. Among them, species richness and individual number of aquatic insects were the highest, and Caenis was the dominant species. The richness and number of collector-gatherers and intermediate species were the main components in terms of functional feeding groups and species sensitivity to stressors, respectively. Spearman correlation analysis showed that Shannon-Wiener diversity index was significantly negatively correlated with chemical oxygen demand（COD_（Cr））（r =-0.515, P = 0.007） and total phosphorus（TP）（r =-0.665, P = 0.000）. BI was significantly positively correlated with COD_（Cr）（r = 0.406, P = 0.040） and TP（r = 0.704, P = 0.000）. Canonical correspondence ordination analysis（CCA） showed that TP, Zn, COD_（Cr）, water temperature（WT）, and pH were the major contributors to the structure of macroinvertebrate community. Ephemeroptera and Oligochaeta were the main indicators of environmental changes. Both the Shannon-Wiener diversity index and BI showed that the water quality of the Puyang River was marginally or moderately polluted in general. The water quality of mainstem was marginally better than its tributary, and the water quality upstream was clean; however, a few sites in the middle and lower stream were heavily polluted. The present study revealed that water pollution is the major factor inf luencing the macroinvertebrate community composition and structure at the Puyang River, furthermore, and the study suggests that macroinvertebrate community could recover following the decline in the concentration of pollutants, such as TP and COD_（Cr）.