三峡水库蓄水期长江万州段干支流浮游动物群落特征研究

Research on Zooplankton Community in the Mainstream of Yangtze River and Its Tributaries of Wanzhou Section During Impounding

为探明三峡水库蓄水后浮游动物的群落结构变化,于2017年11月调查了三峡库区长江万州段干、支流的水质情况以及浮游动物种类和组成变化,分析了浮游动物和水体环境因子之间的关系以及长江干流浮游动物的演替情况。结果表明:流经万州城区的长江干、支流水质都已达到富营养化状态,且支流的污染程度比干流更严重。浮游动物共检出28属39种,以原生动物和轮虫为主。长江干流的浮游动物优势种类有5种,支流有9种。典范对应分析发现,硝态氮和总悬浮物是影响冬季浮游动物种群变化最重要的环境因子。分析三峡库区万州及其周边地区长江干流浮游动物的长期演替发现,随着水环境的稳定,水体中原生动物的种类逐渐从喜流水型向喜静水型转变。与2012年同期相比,本次调查中原生动物和轮虫的相对丰度增加,浮游动物生物多样性减少,这可能和水位波动的长期影响和城市水体污染有关。

In order to provide an insight of the zooplankton community during the impoundment period of the Three Gorges Reservoir, we investigated the water quality and the species composition of zooplankton in November 2017, and further analyzed the relationship between zooplankton species and water quality, and zooplankton succession in the mainstream of the Yangtze River in Wanzhou, Chongqing. The results revealed that the water quality of the Yangtze River was much better than its tributaries. The identified zooplankton could be categorized into 28 genera and 39 species, and protozoa and rotifers were the dominating species. There were 5 dominant species in the mainstream of Yangtze River and 9 in its tributaries. The result of canonical correspondence analysis showed that nitrate and total suspended solid were the main environmental factors which controlled the variation of zooplankton community in winter. For the long-term succession of zooplankton community in the study area and its adjacent areas, it was suggested that the species of protozoa gradually shifted from the mobile-preference type to the stationary-preference type according to the stability of water environment. Comparing to the same period in 2012, the relative abundance of protozoa and rotifers in the current study were higher, while the zooplankton diversity was lower, and these might be associated with the long-term impacts of water level fluctuation and urban water pollution.