三峡库区试验性蓄水期间浮游生物群落特点研究

Research on plankton community in Three Gorges Reservoir during its trial impoundment

蓄水改变了三峡水库的水文情势,使得浮游生物密度及群落结构出现明显改变,在不同蓄水阶段呈现不同的特点。根据2009年三峡水库试验性蓄水期间分季节实地监测结果,分析了浮游动植物在不同季节、不同蓄水位以干流与支流河口的分布变化情况。结果表明:就季节变化而言,秋季浮游植物种类最多、夏季次之、冬春较少;浮游生物密度整体不高,且时空分布不均,为春夏秋冬依次递减,支流河口密度高于干流;与蓄水前相比,蓄水后浮游生物密度显著增加,但与135 m及156 m蓄水位相比,试验性蓄水期间有下降趋势。库区营养盐水平较高,对浮游生物的生长不形成限制,浮游生物分布的时空显著差异是由流量、流速及浊度造成的。

The impoundment changed the hydrological regime of Three Gorges Reservoir, as well as the density and structure of plankton community which has different characteristics in different impoundment periods. According to the monitoring result of plankton community in the reservoir in 2009, the variation condition of the distribution of plankton community in different sea- sons, different impoundment levels and in the mainstream and tributary mouths are analyzed. The analysis result show that as for seasonal change, phytoplankton species are rich in autumn, and followed by summer, winter and spring; zooplankton is not high in density generally and distributes unevenly in time and space and its density is in the order of spring, summer, autumn and winter, the density in tributary mouths is higher than that in mainstream; compared with that before impoundment, the density of plankton community increases obviously after impoundment, but has a decease tendency compared with those in 135 m and 156 m impoundment. The nutrient salt level in the reservoir is higher which is favorable to growth of plankton, and the temporal and spatial distribution difference of plankton is caused by discharge, flow velocity and water turbidity.