东平湖浮游动物对南水北调东线运行的时空响应

东平湖是南水北调东线工程输水线路下游的最后一个调蓄湖泊。为探究调水后的东平湖浮游动物时空响应,于2016—2017年对东平湖浮游动物进行了涵盖春(4月)、夏(7月)、秋(10月)、冬(1月)的4次调查,共检出浮游动物3类72种(属),其中,轮虫51种(70.83%)、枝角类11种(15.28%)、桡足类10种(13.89%)。东平湖不同区域优势种的季节演替明显:进水区夏季前三位优势种均为桡足类,即剑水蚤(Cyclops sp.)、真剑水蚤(Eucyclops sp.)、桡足幼体(Copepodid);湖中区及出水区秋季前三位优势种相同,均为枝角类及桡足类,即真剑水蚤、剑水蚤和直额裸腹溞(Moina rectirostris);各区域其余季节均主要为轮虫。浮游动物密度、Shannon-Wiener多样性指数与Marglef丰富度指数在不同季节间均差异显著,在不同区域间无显著差异。进水区与出水区浮游动物密度均为夏季最高、冬季最低,湖中区浮游动物密度为秋季最高、冬季最低。浮游动物Shannon-Wiener多样性指数与Marglef丰富度指数的季节变化规律一致,进水区为秋季最高、冬季最低,湖中区及出水区均为夏季最高、冬季最低。调水在一定程度上影响了东平湖浮游动物的群落结构,是东平湖浮游动物出现小型化趋势的可能原因之一,同时调水也有利于东平湖的水质改善。

Spatio-Temporal Responses of Zooplankton to the Operation of the Eastern Route of the South-to-North Water Diversion Project in Dongping Lake

Dongping Lake is the last regulating lake in the downstream of the Eastern Route of China’s South-to-North Water Diversion Project.To assess the responses of spatio-temporal patterns of zooplankton to the water diversion,seasonal studies(spring,summer,fall and winter)were conducted in Dongping Lake from April 2016 to January 2017.A total of 72 species(genera)of zooplankton were identified,of which 51 species belonging to rotifers(70.83%),11 species belonging to cladocerans(15.28%)and 10 species belonging to copepod(13.89%).Seasonal succession of dominant species was significant in different regions of Dongping Lake.The top three dominant species in the inflow area in summer were copepod,which were Cyclops sp.,Eucyclops sp.,Copepodid.And the top three dominant species in the middle and outflow areas in autumn were cladocerans and copepod,which were Eucyclops sp.,Cyclops sp.,Moina rectirostris,while the rest of the season was mainly rotifers in each region.Zooplankton density,Shannon-Wiener diversity index and Marglef richness index varied significantly among seasons but not among regions.Zooplankton density was the highest in summer and the lowest in winter in the inflow and outflow areas,and zooplankton density was the highest in autumn and the lowest in winter in the middle area.Seasonal variations of Shannon-Wiener diversity index were consistent with those of Marglef richness index.The Shannon-Wiener diversity index and Marglef richness index in the inflow area were the highest in autumn and the lowest in winter,the middle area and the outflow area were both the highest in summer and the lowest in winter.The zooplankton community structure in Dongping Lake was affected to some extent by the water diversion,the size of zooplankton had a tendency towards miniaturization,and the water diversion was beneficial to water quality improvements in Dongping Lake.