水库鱼类放养密度对浮游动物群落结构的影响

以南亚热带地区2010年3座不同养殖密度的和龙水库、百花林水库、芙蓉嶂水库为对象,研究了浮游动物群落的结构特征,分析和探讨滤食性鱼类捕食对浮游动物群落结构的影响.3座水库浮游动物生物量均较低,不超过1.0 mg/L.高养殖密度、富营养水平的和龙水库浮游动物生物量显著低于其它2座水库,中等养殖密度、富营养水平的百花林水库则高于低养殖密度、贫-中营养水平的芙蓉嶂水库.和龙水库浮游动物全年以轮虫为主要优势类群,优势种为前节晶囊轮虫(Asplanchna priodonta)；芙蓉嶂水库和百花林水库3月和12月浮游动物以枝角类为优势类群,优势种为长额象鼻溞(Bosmina longirostris)、颈沟基合溞(Bosminopsis deitersi)、模糊秀体潘(Di-aphanosoma dubium),8月为桡足类,优势种为舌状叶镖水蚤(Phyllodiaptomus tunguidus).3座水库年均浮游动物与浮游植物生物量比值均小于0.1,与年渔获量呈显著负相关关系.高强度的滤食性鱼类捕食使得下行效应比上行效应更强烈,浮游动物表现出低生物量和小个体种类占优势的特征.

The effect of farming fish density on zooplankton community of reservoirs in southern China

To assess the potential differences in predation impact on zooplankton by filter-feeding fish, zooplankton communities of three reservoirs with different fish densities and trophic levels in southern China were investigated. Zooplankton biomass was below 1.0 mg/L in the three reservoirs. Helong reservoir , which was eutrophic and cultured with highest density of filter-feeding fish, its zooplankton biomass was significantly lower than that in the two other revervoirs. Baihualin Reservoir which was eutrophic with medium fish density ,zooplankton biomass was much higher than Furongzhang Reservoir which was oligo-mesotrophic with low fish density. While zooplankton community was dominated by rotifera(Asplanchna priodonta) in Helong Reservoir all year round. The zooplankton were dominated by cladorcera (Bosmina longirostris,Bosminopsis deitersi ,Di-aphanosoma dubium) in March and December , and by copepoda(Phyllodiaptomus tunguidus) in August in Furongzhang and Baihualin . Biomass ratios of zoophyto was always below 0.1 in the three reservoirs and had a significantly negative correlation with annual fish catch. Consequently , high predation by filter-feeding fish caused low biomass and dominance in small-sized zooplankton species in three reservoirs.