【摘要】 梯级水电开发对于河流生态系统具有复杂和深远的影响,大型底栖动物及沉积物可以很好地反映水生态系统的变化及演替趋势。结合澜沧江干流梯级水电开发,分别于2011年和2016年在漫湾库区开展大型底栖动物及沉积物定点采样调查,分析梯级水坝运行对库区大型底栖动物群落结构及生物多样性的影响,采用潜在生态风险指数(RI)对库区沉积物重金属(As、Cd、Cr、Cu、Pb和Zn)的生态风险进行评估,基于CCA和Pearson相关分析研究了大型底栖动物群落与重金属沉积的相互作用关系。结果表明,澜沧江梯级水坝运行后,漫湾库区静水区大型底栖动物群落密度和生物量增加明显,特别是软体动物中的河蚬河蚬(Corbicula fluminea),其密度和生物量在库区静水区占据绝对优势;库区静水区Margalef丰富度指数(d)增加显著,而Shannon-Weaver指数(H′)表现为旱季降低,雨季增加的趋势;库区沉积物重金属主要生态风险来源于Cd,其次为As,重金属潜在生态风险指数(RI)在静水区增加明显,特别是高水位的旱季,而过渡区增加不大;CCA分析表明沉积物中重金属Cr、As、Pb的含量对大型底栖动物群落及物种组成影响较大;Pearson相关分析表明昆虫纲密度与沉积物中Cr的含量呈显著正相关(P<0.01),软体动物门密度与Cd、As、Cu、Zn、Pb的含量和重金属潜在生态风险指数(RI)呈显著正相关(P<0.01)。随着澜沧江梯级水坝的运行,漫湾库区大型底栖动物群落及沉积物仍处于动态变化过程中,需进行长期的定点监测及深入研究。更多还原

【Abstract】 Cascading hydropower dams exploitation may exert complex and long-term effects on river ecosystem. The changes and dynamics of aquantic ecosystem can be indicated by benthic macroinvertebrate assemblages and sediments. Along the mainstream of Lancang River with the cascading hydropower dams exploitaiotn, the fixed-point monitering of benthic macroinvertebrate assemblages and sediments were carried out in 2011 and 2016 respectively. The structure, biodiversity of benthic macroinvertebrate assemblages were anlysised. By using potential ecological risk index(RI), the ecological risk of heary metals(As, Cd, Cr, Cu, Pb,and Zn) in sediments were evaluated. CCA and Pearson correlation analysis were performed to examine the interaction relationship between benthic macroinvertebrate assemblages and heavy metal deposition. The results showed that the density and biomass of benthic macroinvetebrate assemblages, especially the Corbicula fluminea of Mullusca whose density and biomass dominated in the lacustrine zone of this reservoir, increased significantly in the lacustrine zone of Manwan Reservoir after the cascading hydropower dams operation in Lancang River. In the lacustrine zone, the Margalef richness index(d) increased significantly, and the Shannon-Weaver index(H′) decreased in the dry season but increased in the rainy season. The ecological risk of heavey metals in sediment were mainly caused by Cd, followed by As. The potential ecological risk index(RI) of heavy metals increased significantly in the lacustrine zone, especially in the high water level period of dry season, while it increased insignificantly in the transition zone.CCA analysis showed that the content of Cr, As and Pb of heavy metals had great influence on the benthic macroinvertebrate assemblages and species composition. The Pearson correlation analysis showed that the density of Insecta were significantly positively correlated(P<0.01) with the content of Cr, the density of Mullusca were significantly positively correlated(P<0.01) with the content of Cd, As, Cu, Zn, Pb, and the potential ecological risk index(RI) of heavy metals. With the operation of the cascading hydrowower dams, the benthic macroinvertebrate assemblages and sediments would continuously change in the dynamics.Therefore, the long-term fixed-point monitoring and assessment should be strenghted.更多还原