大渡河乐山段2013-2016年浮游动物群落特征变化

Zooplankton Community Characteristics in the Leshan Section of Dadu River from 2013 to 2016

为了解大渡河沙湾至乐山段安谷水电站建设过程中浮游动物群落变化,于施工期2013-2014年和运行期2015-2016年的每年春、秋两季对主河道、左侧河网及支流浮游动物群落进行监测。结果显示,2013-2016年调查共鉴定出浮游动物263种,优势种为12种属,旋轮虫属(Philodina)为施工期、运行期共有优势种属。浮游动物平均密度为658.55个/L,平均生物量为0.1102 mg/L;施工期和运行期浮游动物密度和生物量差异不显著,春季平均密度最高值出现在2014年(621.15个/L),秋季平均密度最高值出现在2015年(674.19个/L),2013年春、秋季的生物量均为最高(0.1324 mg/L、0.1070 mg/L),浮游动物密度和生物量在季节分布上差异不大。在空间分布上,支流高于主河道、左侧河网、岷江。施工期、运行期浮游动物密度、生物量与环境因子溶解氧(DO)、流速(V)呈负相关,与水温(WT)、氨氮(NH4+-N)、硝氮(NO3--N)、总氮(TN)、磷酸盐(H3PO4)、总磷(TP)、高锰酸盐指数(CODMn)呈正相关。RDA显示,NO3--N在2014年、2015年对浮游动物影响占主导作用,2016年透明度(SD)是影响浮游动物群落的主要因子。不同时期浮游动物现存量对比,蓄水期因水温偏低导致密度和生物量最低;在空间分布上坝前受安谷水电站建设影响较大。研究表明,安谷水电站在建设过程中浮游动物群落特征差异不大。

Angu hydropower station is on the Shawan-Leshan section of Dadu River.In this study,we analyzed the zooplankton community in the mainstream,left river network and tributaries of the Leshan section during the construction(2013-2014)and operation(2015-2016)of the hydropower station.We aimed to understand the long term changes in the structure of the zooplankton community,and provide basic data to guide continuing research on the long-term ecological effects on aquatic organisms in the lower Dadu River and ecological restoration in the watershed.In May(spring)and October(autumn)of 2013-2016,monitoring of zooplankton and water quality was carried out at 11 sampling sites in the main stream,left river network and tributaries of the Leshan section of Dadu River.A total of 263 zooplankton species were identified,consisting of protozoans(130 specie,63 genera),rotifers(80 specie,30 genera),cladocerans(23 specie,13 genera)and copepods(30 specie,15 genera).Zooplankton species numbers were significantly different between the construction period and operation period,with higher species richness in 2013(147 species)and 2014(143 species),than in 2015(101 species)and 2016(119 species).A total of 12 dominant species(genera)were detected during the investigation,and Philodina was the dominant genus in both the construction and operation periods.The average zooplankton density and biomass were 658.55 ind/L and 0.1102 mg/L,with no significant differences between construction and operation periods.Seasonally,the highest average spring density(621.15 ind/L)occurred in 2014 and the highest average autumn density(674.19 ind/L)occurred in 2015,and the highest biomasses for spring and autumn(0.1324 mg/L,0.1070 mg/L)both occurred in 2013.However,none of the seasonal differences were significant.Spatially,zooplankton density and biomass in the tributaries were higher than those in the mainstream,left river network and Minjiang River.Zooplankton density and biomass during the construction and operation periods were negatively correlated with the environmental factors DO and velocity(V),and positively correlated with WT,NH_(4)^(+)-N,NO_(3)^(-)-N,TN,H_(3)PO_(4),TP,and CODMn.Redundancy analysis shows that NO_(3)^(-)-N had a dominant effect on zooplankton in 2014 and 2015,and SD became the primary affecting factor in 2016.Zooplankton standing crops in different periods were compared in this study,and results show that the zooplankton community presented few changes during construction of Angu hydropower station.The lowest density and biomass were recorded during the water impoundment period due to low water temperature,and zooplankton above the dam were most affected by the construction of Angu hydropower station.