长江干流浮游动物群落结构及时空分布格局

Zooplankton community structure and spatio-temporal dynamics in the main stream of the Yangtze River

浮游动物是河流食物网的重要组成部分,在河流生态系统的能量流动和物质循环中具有重要作用,然而截至目前,尚缺乏对长江干流宏观尺度浮游动物的全面调查。本研究于2018—2019年,在长江干流约5000 km江段设置51个调查站位,并于每年鱼类繁殖期(3—6月)、育肥期(8—10月)和越冬期(11—1月)各开展1次调查,系统调查分析了长江干流浮游动物群落结构特征及时空分布格局。结果显示,(1)种类:长江干流浮游动物共187种,其中原生动物56种、轮虫59种、枝角类34种、桡足类38种;三峡库区是浮游动物种类数最丰富的水域(87种),其余分别为金沙江(59种)、长江上游(68种)、长江中游(54种)、长江下游(56种)。鱼类繁殖期是浮游动物种类最丰富的季节,分别为金沙江(45种)、长江上游(56种)、三峡库区(47种)、长江中游(41种)、长江下游(32种)。(2)密度:长江干流浮游动物密度范围为1.12~644.40个/L,中游、下游密度显著高于上游;密度高值一般出现在繁殖期,低值一般出现在鱼类育肥期。(3)生物量:长江干流浮游动物生物量范围为231.78×10^(-5)~45638.57×10^(-5)mg/L,中游、下游和金沙江明显高于长江上游和三峡库区。(4)优势种:主要包括原生动物恩茨筒壳虫、淡水麻铃虫、普通表壳虫,轮虫类萼花臂尾轮虫、针簇多肢轮虫,桡足类广布中剑水蚤、特异荡镖水蚤,无节幼体等。研究表明,长江干流浮游动物群落结构和时空分布呈现典型河流特征,种类和数量较贫乏,群落以轮虫和原生动物等小型个体为主,河流中、下游丰度高于上游,呈现明显的季节动态规律。研究成果可为长江水生态管理提供重要基础数据。

Zooplankton is an important part of the river food web and plays an important role in the energy flow and nutrient cycling of the river ecosystem.However,there is a lack of systematic survey of zooplankton in the main stream of the Yangtze River.During 2018–2019,fifty-one survey stations were set up in about 5000km of the main stream of the Yangtze River.And the surveys were carried out during the fish reproductive(March to June),feeding(August to October)and wintering(November to January)seasons every year.And the zooplankton community structure and distribution in the main stream of the Yangtze River were systematically studied.The results showed:(1)There were 187 species of zooplankton in the main stream of the Yangtze River,including 56species of protozoa,59 species of rotifers,34 species of cladocerans and 38 species of copepods.The species of zooplankton was most abundant in the Three Gorges Reservoir.And the species of zooplankton in each river reach were as follows:59 species in Jinsha River,68 species in the upper reaches of the Yangtze River,87 species in the Three Gorges Reservoir,54 species in the middle reaches of the Yangtze River,and 56 species in the lower reaches of the Yangtze River.The species of zooplankton was the most abundant in the fish reproductive season.And the zooplankton species in the breeding season of each river reach were as follows:45 species in Jinsha River,56 species in the upper reaches of the Yangtze River,47 species in the Three Gorges Reservoir,41 species in the middle reaches of the Yangtze River,and 32 species in the lower reaches of the Yangtze River.(2)The density of zooplankton in the main stream of the Yangtze River ranged from 1.12 to 644.40 ind./L.In the middle and lower reaches of the main stream of the Yangtze River,the zooplankton densities were significantly higher than that in the upper reaches.The high value of zooplankton density generally occurred during the fish reproductive season,and the low value generally occurred during the fish feeding season.(3)The zooplankton biomass:in the main stream of the Yangtze River,the zooplankton biomass ranged from 231.78 to 45638.57×10^(-5)mg/L.And the zooplankton biomass in Jinsha River,the middle and lower reaches of the Yangtze River were significantly higher than that in the upper reaches and the Three Gorges Reservoir.(4)The dominant species of zooplankton in the main stream of the Yangtze River mainly included Tintinnidium entzii,Leprotintinnus fluviatile,Arcella vulgaris,Brachionus calyciflorus,Polyarthra trigla,Mesocyclops leuckarti,Neutrodiaptomus incongruens and Nauplius.The community structure and distribution of zooplankton in the main stream of the Yangtze River showed typical lotic freshwater zooplankton characteristics.The species and numbers were poor in the river.Small animals such as rotifers and protozoa played an important role in the community.The abundance of zooplankton varied from upstream to downstream and changed with season.The research results can provide important basic data for the aquatic ecology management of the Yangtze River.