港口湾水库对下游大型底栖动物群落结构的影响

Impact of Gangkouwan Reservoir on the Downstream Macrozoobenthos Community

为研究西津河港口湾水库对下游大型底栖动物群落结构的影响,分别在水库上下游的兵坑口桥、港口湾水文站点、宁国老水文站和西津大桥4个站点进行底栖动物采样调查及鉴定,共采集大型底栖无脊椎动物22 315个;应用底栖动物物种组成和功能摄食类群等参数来衡量水库对河流底栖动物群落结构的影响,并结合河流生境的变化对底栖动物群落结构做了简单分析。结果表明,坝上游底质以鹅卵石(54.46%)和砾石(43.56%)为主,坝下组以鹅卵石、砾石和大石块为主,且坝上下游水体各理化指标均出现波动但并不显著;下游距离大坝1 km处的港口湾水文站点物种丰富度和EPT分类单元数显著降低(P=0.016,P=0.003),滤食者比例显著升高(P=0.011),刮食者和捕食者比例显著下降(P=0.011,P=0.013);而多度指数、Shannon-Wiener多样性指数、Simpson优势度指数和Pielou均匀度指数等群落参数在各样点间无显著差异;群落结构相似性分析也表明,港口湾水文站点群落结构与其他样点存在显著差异。研究成果可为水利工程对生态系统影响的评价及生态恢复提供参考。

Benthic macroinvertebrates are widely used for assessing the ecological impact of hydraulic projects.Gangkouwan Reservoir,located on the Xijin River in Zhejiang Province,has significantly altered the natural flow regime. The impact of Gangkouwan Reservoir on the benthic macroinvertebrates community was studied to better understand the impact on the river ecosystem and provide a scientific basis for conserving and managing the river＇s resources. In April,June,July,September and November of 2013 and January of 2014,zoobenthos sampling was carried out at four locations. Site1 is above the dam where human disturbance is small and Sites 2- 4 are below the dam where human activity is more intensive. Environmental parameters were measured in situ： water temperature,p H,conductivity,dissolved oxygen,flow velocity and depth. A total of 22 315 macroinvertebrates belonging to 107 genera and 65 families were collected. The macroinvertebrate community structure was characterized by analyzing the composition of the community and the functional feeding groups while also considering the available substrate.The primary substrate components above the reservoir were pebbles（ 54. 46%） and gravel（ 43. 56%）. Below the reservoir the substrate was also primarily pebbles and gravel,but included boulders. The physicochemical parameters of the water body did not fluctuate significantly at any of the sites. The species richness and EPT taxa richness of the macroinvertebrate community at Site 2（ Gangkouwansite）,1 km below the dam,decreased significantly（ P = 0. 016,P = 0. 003）. The density,Shannon-Wiener diversity index,Simpson dominance index and Pielou evenness index did not vary significantly among sites. Functionally,the filter feeders increased significantly（ P = 0. 011） and the predators and scrapers decreased significantly（ P = 0. 011,P = 0. 013）. Similarity analysis（ ANOSIM） of the macroinvertebrate communities for the four sites shows that the community structure above the dam was significantly different from the three sites below the dam. This study provides valuable information for the ecological assessment and restoration of rivers impacted by dam construction.