一座热带浅水水库敞水区浮游甲壳动物群落结构

为了解热带中小型浅水型水库枯水期浮游动物群落组成与结构稳定性,于2006至2007的三个枯水期,对位于我国雷州半岛甘村水库敞水区进行了每周一次的高频采样,主要以个体大小作为变量分析了浮游甲壳类动物的群落结构的组成.三次枯水期采样中,敞水区中只检测到枝角类4种和桡足类4种.浮游甲壳类的体长范围多集中在400～700μm之间.枝角类的优势种为模糊秀体溞平均体长为533μm,桡足类成体优势种台湾温剑水蚤的平均体长为787μm,无节幼体和剑水蚤桡足幼体丰度与生物量也相对较高.水库浮游甲壳类种类数和丰度的峰值均出现在体长为300～400μm和400-500μm两个等级内.浮游甲壳类的种类和数量均是以小个体为主,除了营养水平还与水体中的捕食压力紧密相关,鱼类的捕食对于浮游甲壳类群落结构的形成作用显著.

Size structure of the planktonic crustacean community in the pelagic zone of a shallow tropical reservoir

In order to understand the structure of zooplankton community in shallow tropical reservoirs and its stability in dry seasons, we sampled in the pelagic zone of Gancun Reservoir every week which in three dry seasons from 2006 to 2007. Gancun Reservoir is a typical shallow tropical waterbody, located in the Leizhou Peninsula of Guangdong Province. Similar to most of tropical waterbodies with a low diversity, in total, only 8 speciesof crustacean had been identified in this reservoir. The average body length of the crustacean was between 400μm and 700μm. Diaphanosoma dubium is the dominant species in cladocerans, having an average body length 533μm, while in copepoda, Thermocyclops taihokuensis dominate with an average body length 787μm. Nauplii and cylopoid copepodites contributed a majority of the abundance and biomass of the whole community. In the size distribution of abundance and the number of species, the peaks occurred at the two length classes of 300-400μm and 400-500μm. Low abundance and species diversity in the pelagic zones was in coincidence with a relatively high-yield fishery in the reservoir, the high predation pressure was a main force in structuring the size distribution of crustacean community.