南亚热带富营养化抽水型水库轮虫的组成与动态

Species composition and quantitative dynamics of rotifers in a pumped storage,eutrophic reservoir in South China

大镜山水库位于广东省珠海市,是一座供应珠海市和澳门特别行政区饮水的抽水型中型水库.抽水改变了水体的水动力过程以及水体生态系统的动态过程.为了解这一动态过程中轮虫的群落结构及环境因子对轮虫的影响,于2005年1-12月,每月一次对该水库敞水区进行了采样调查.共采集到轮虫32种,其中,臂尾轮科12种,异尾轮科、腔轮科各有4种,它们主要是热带、亚热带地区的常见种和优势种类.热带龟甲轮虫(Keratella tropica)、对棘异尾轮虫(Trichocerea stylata)、螺形龟甲轮虫(Keratella cochlearis)、迈氏三肢轮虫(Filinia matior)、裂痕龟纹轮虫(Anuraeopsis fissa)、角突臂尾轮虫(Brachionus angularis)、剪形臂尾轮虫(Brachionus forficula)、卵形无柄轮虫(Ascomorpha ovalis)、敞水胶鞘轮虫(Collotheca pelagica)和卜氏晶囊轮虫(Asplanchna brightwelli)为优势种,这些优势种个体小、具有硬被甲.轮虫的多样性指数在0.29-0.81之间变动,与相同营养水平的湖泊相比,大镜山水库轮虫的种类数和多样性指数均较低.轮虫丰度和生物量的分布范围分别为21-1094ind./L和4.04-1127μg/L,高峰期均出现在2月和5月,二者具有相似的动态特征.轮虫个体的大小范围在50-620μm之间,轮虫种类和丰度的组成均以200μm以下的小型个体为主,如裂痕龟纹轮虫、角突臂尾轮虫等.轮虫生物量组成主要是以200-400μm的中型个体为主,如卜氏晶囊轮虫、萼花臂尾轮虫(Brachionus Calyciflorus)等.温度、透明度、浮游植物生物量和蓝藻生物量是影响水库轮虫群落结构特征和动态的主要环境因子.

Dajingshan Reservoir, located in Zhuhai City, South China, is a medium-size water body. It supplies drinking water for the Zhuhai City and Macao in dry seasons. Water is pumped into the reservoir from a nearby river in dry seasons so as to enhance the water storage. Pumped water modified the hydrodynamic processes and ecosystem dynamics. In order to understand the dynamic of rotifer community and the relationships between specific composition of rotifers and the environmental variables, an investigation was conducted monthly in 2005. Altogether 32 species of rotifer were identified, among which 12 species were belonged to Brachionidae, 4 species to Trichocereidae and 4 species to Lecanidae. The majority of the species are tropical or sub-tropical species. Keratella tropica, Trichocerea stylata, Keratella cochlearis, Filinia maior, Anuraeopsis fissa, Brachionus angularis, Brachionus forficula, Ascomorpha ovalis and Collotheca pelagica were the dominant species. They had small body size and lorica. The diversity index of rotifers ranged from 0.29 to 0.8, which were lower than that in Lake Donghu and Lake Xinghu. The abundance and biomass of rotifers ranged from 21 to 1094ind./L and from 4.04 to 1127μg/L, respectively. The maximal abundance and biomass occurred in February and May, respectively. The body length of rotifers ranged from 50μmto 620μm. The total abundance of rotifers was contributed by of small-sized species with a body size less than 200μm, while the rotifers biomass was dominated by medium-sized species with body size from 200-400μm. Secchi disk depth, temperature, total phytoplankton biomass and Cyanophyta biomass were the main factors affecting the species composition and quantitative dynamics of the rotifer community.