浑河主要污染物对大型底栖动物空间分布的影响

利用典范对应分析（CCA）方法研究浑河大型底栖动物与污染物关系。结果表明，现阶段影响浑河大型底栖动物群落特征的主要污染物为NH3-N和CODCr；回归分析表明，NH₃-N和COD_Cr与大型底栖动物物种数和EPT物种（敏感种）数具有显著相关关系，当COD_Cr和NH₃-N浓度分别高于16.0和1.0 mg/L时，大型底栖动物物种数与EPT物种数均小于浑河流域平均水平。浑河大伙房水库上游的大型底栖动物生物多样性相对较高；水库下游由于NH₃-N和COD_Cr的污染，降低了大型底栖动物的生物多样性，其中NH₃-N和COD_Cr均与Margalef丰富度指数呈显著负相关关系（P<0.05），而NH₃-N还与香农-威纳指数、Pielou均匀度指数和Simpson多样性指数呈显著负相关关系（P<0.05）。CCA分析还表明，大伙房水库上游主要指示物种以桃碧扁蚴蜉（Ecdyonurus tobiironis），黑头原石蛾（Rhyacophila nigrocephala），蝶石蛾（Psychomyia sp.）等清洁物种为主；水库下游支流指示种主要以苏氏尾鳃蚓（Branchiura sowerbyi），赤豆螺（Bithynia fuchsianus）和水蝇（Ephydra sp.）等耐污物种为主；水库下游干流指示种以鳞（虫兆）属（Tomocerus sp.），钩虾（Gammarus sp.）和铜锈环棱螺（Bellamya acruginosa）等耐污物种为主。

Effects of Main Contaminations on the Spatial Distribution of Macroinvertebrates in the Hun River

The relationship between the macroinvertebrate communities and pollutants was evaluated in the Hun River by applying the Canonical Correspondence Analysis (CCA). The results showed that ammonium-nitrogen (NH3-N) and chemical oxygen demands (CODCr) were the two primary pollutants affecting the spatial distribution of macroinvertebrates. The regression analysis revealed that total number of taxa and EPT taxa, which represented the most sensitive taxa, would be lower than the average values in the Hun River when the concentration of NH3-N and CODCr was above 1.0 mg/L and 16.0 mg/L, respectively. The biodiversity was relative higher at the upstream region comparing with downstream regions of Dahuofang Reservoir, which was caused mainly by the NH3-N and CODCr pollution. Both NH3-N and CODCr had significantly negative correlations with Margalef’s diversity index(P<0.05), and NH3-N also had significantly negative correlations with Shannon-Wiener index, Pielou’s evenness, and Simpson’s diversity index(P<0.05). Several indicators were identified through the biplot of species-environmental ordination of CCA. The Ecdyonurus tobiironis, Rhyacophila nigrocephala and Psychomyia sp. could represent the sensitive indicators of the upstream regions of Dahuofang Reservoir. Meanwhile, the tolerant taxa of Branchiura sowerbyi, Bithynia fuchsianus, and Ephydra sp. represented the main indicators at the tributaries of downstream region of Dahuofang Reservoir. At the same time, the tolerant taxa of Tomocerus sp., Gammarus sp. and Bellamya acruginosa were the main indicators at the main channel of in the downstream region of Dahuofang Reservoir.