三峡水库初次蓄水后干流库区桡足类的纵向分布与季节变化

作为大型水利工程, 三峡水库于2003年6月开始蓄水, 蓄水后库区水环境发生了变化。为了了解三峡水库水生态系统的演替规律, 同时为环境保护、渔业资源开发利用以及水环境管理提供理论基础, 我们对三峡水库第一阶段蓄水后桡足类的季节变化和空间分布进行了周年季节性研究。在三峡库区江津至茅坪的10个断面共采集到8种桡足类, 其中哲水蚤目2种、猛水蚤目1种、剑水蚤目5种, 北碚中剑水蚤(Mesocyclops pehpeiensis)、广布中剑水蚤(M. leuckarti)和汤匙华哲水蚤(Sinocalanus dorrii)分布较广。各样点种类数差异不大, 但组成上却有不同。桡足类种类组成、空间分布和密度具有明显的季节变化特征, 此外密度在水库的纵轴上也表现出明显的梯度分布, 越近大坝密度越高。

Seasonal variation and longitudinal distribution of copepods in the main river area of the Three Gorges Reservoir

The ecosystem of the Three Gorges in Yangtze River was changed into an artificial lake(reservoir) ecosystem after impoundment in June 2003.We surveyed the seasonal variation and spatial distribution of copepods from April 2004 to January 2005 in order to provide basic data for clarifying the successional pat-tern of the ecosystem.From Jiangjin to Maoping,eight copepod species were collected,belonging to Ca-lanoida,Harpacticoida,and Cyclopoida.Of these,Mesocyclops pehpeiensis,M.leuckarti and Sinocalanus dorrii had a relatively wide distribution.No distinct difference in species number was found among sampling sites,but the species composition was different.Species composition,distribution and density of copepods showed significant seasonal variation.Copepod density showed an obvious gradient with the distance from the reservoir dam:the nearer to the dam,the denser the copepods.