中文摘要：

中华窄腹剑水蚤是中国河流中发现的土著种类，具有较强的生态入侵能力，通过从西江抽水进入大镜山水库，成为该水库的优势浮游甲壳类．通过2005-2006两年的采样监测，初步分析了该水库中中华窄腹剑水蚤的种群特征及其对浮游甲壳类的群落动态和结构的影响．两年共检出浮游甲壳类13种，其中，桡足类4科7属9种，枝角类3科4属4种，中华窄腹剑水蚤是水库的优势种．两年浮游甲壳类丰度的范围是3．82-364．85ind见，峰值出现在春季，两年变化趋势相似．水库浮游甲壳类的体长分布范嗣为0．07-1．25mm，主要由小个体的类群（体长在0．07-0．4mm之间）组成，个体较大（大于0．5mm）的枝角类和桡足类数量很低．中华窄腹剑水蚤和其无节幼体的丰度占甲壳类总丰度的50％以上，其丰度的动态分布与浮游甲壳类的总体丰度的动态分布一致中华窄腹剑水蚤主要以三种形式（无节幼体I期，桡足幼体后期和成体）存在于水体中，存活曲线呈Ⅲ型，无节幼体的丰度远高于后两者之和．该种类能成为水库优势种主要是南水库成度变化剧烈水环境特征和其自身的生态学特点决定的．中华窄腹剑水矗丰度与叶绿素a浓度具有显著正相关性，与抽水入库量具有极显著的负相关性．作为一个生态入侵种类，中华窄腹剑水蚤降低水体中浮游甲壳类生物多样性，并替代了原来的土著优势种．

英文摘要：

Limnoithona sineseis is considered as an endemic species in rivers of China with strong invasive ability. It was introduced to some reservoirs by pumping water and becomes the dominant species in the new water bodies. To understand the population dynamics of Limnoithona sineseis and its effects on the pelagic crustaceans, we investigated Dajingshan reservoir, a typical pumped storage reservoir located in Zhuhai City, South China in 2005 and 2006. In total, 13 species of crustaceans including 9 copepods（4 family 7 genera） and 4 cladocerans （3 family 4 genera） were identified. Limnoithona sineseis was dominant over the sampling periods. The abundance of the crustaceans ranged from 3.82ind./L to 364.85ind./L, with high abundance in spring. Lirnnoithona sineseis and its nauplius covered more than 50% of the total abundance. The body size of crustacean community in the reservoir had a range from 0.07mm to 1.25mm, and small-size species （within 0.07-0.4mm） was dominant. Population of Limnoithona sineseis was mainly composed of stageI nauplii, copepodite stage and adults. Nauplii had a much higher abundance than copepodites and adults. The abundance ofLimnoithona sineseis was positively related to chlorophyll-a concentration, and negatively related to the pumped water volume. It meant that food was the principle factor affecting the animal population, and the animal had adapted well to its new habitat with relatively uneonstant salinity, and its abundance was reduced by flushing of pumped water. As an invasive species, Limnoithona sineseis had become the dominant species by replacing the former ones （Mesocyclops）, and its high abundance reduced biodiversity of crustaceans.