三峡水库蓄水后期香溪河库湾浮游甲壳动物群落结构

CRUSTACEAN ZOOPLANKTON COMMUNITY IN XIANGXI BAY DURING THE LATER IMPOUNDMENT PERIOD OF THE THREE GORGES RESERVOIR

为了解三峡水库蓄水后期香溪河库湾浮游甲壳动物群落结构及其时空变化,于2015年1月至2017年12月对香溪河库湾浮游甲壳动物进行了逐月采样分析。共鉴定出浮游甲壳动物23种,其中枝角类10种,桡足类13种。出现频率较高的物种均为长江流域常见种,生物量和密度峰值分别出现在5月和6月,在1月和2月则未能采集到标本,生物量和密度在年际间差异显著,但群落组成差异不显著,群落季节变化规律表现为春季-夏季以蚤状溞(Daphnia pulex)和僧帽溞(Daphnia cucullata)大型枝角类占优势,秋季以简弧象鼻溞(Bosmina coregoni)小型种占优势。库中生物多样性指数高于库首和库尾,库首和库尾生物多样性指数差异不明显,生物多样性在季节上同样具有一定差异。CCA分析表明水温、叶绿素浓度和水深是解释浮游甲壳动物群落变化重要因素。我们的研究结果表明尽管香溪河库湾营养盐、水温、浮游甲壳动物生物量和密度均未达到稳定状态,但群落组成在年际间无显著性差异,浮游甲壳动物物种丰富度也高于蓄水初期,生物多样性指数存在一定的时空差异,适当程度的干扰有利于维持浮游甲壳动物较高的生物多样性。

To understand the community structure,temporal and spatial changes of crustacean zooplankton in Xiangxi Bay of the Three Gorges Reservoir during the later impoundment period,monthly sampling from January 2015 to December 2017 and analysis of crustacean zooplankton in Xiangxi Bay of the Three Gorges Reservoir were conducted.A total of 23 species of crustacean zooplankton were identified,of which 10 species belong to Cladocera,and 13 species belong to Copepoda.Species with a higher frequency are the common species in the Yangtze River Basin.The peaks of biomass and density occurred in May and June,respectively.We did not collect specimens in January and February.The interannual differences in biomass and density vary significantly,and the difference of community composition was not significant.Community seasonal pattern in spring and summer was dominated by large size Cladocera(Daphnia pulex and Daphnia cucullata),and in autumn was dominated by small size Cladocera(Bosmina coregoni).The biodiversity index in the middle reservoir was higher than that of the upper regions and downstream parts.There was no significant difference in biodiversity index between upper regions and downstream parts,and there was also difference in biodiversity index of some seasons.Results from CCA showed that water temperature,chlorophyll concentrate and water depth were important factors explaining the change of crustacean zooplankton community.The results showed that nutrient,water temperature,crustacean zooplankton biomass and density all have not reached a stable state,but the community composition in different years was not significant.The richness of Crustacean zooplankton species was higher than that of early reservoir.The biological diversity index has a certain difference in time and space,and an appropriate degree of interference may help maintain high biodiversity diversity.