南京玄武湖隆腺溞(Daphnia carinata)牧食对浮游植物的影响

Effects of Daphnia carinata grazing on the phytoplankton of Lake Xuanwu,Nanjing

隆腺溞(Daphnia carinata)是许多湖泊的常见大型浮游动物,习居于富营养的水域中,以浮游植物为食,且滤食效率较高.通过浮游动物添加实验,研究了隆腺溞对南京玄武湖叶绿素和浮游植物群落结构的影响.结果表明,在隆腺溞组,浮游植物密度较对照组降低了83%,叶绿素较对照组下降了81%,氮、磷营养盐与叶绿素的相关性不显著.浮游植物的群落结构较对照组也发生了很大变化,蓝藻、绿藻和硅藻的比例有显著上升,隐藻呈显著下降趋势,金藻、甲藻和裸藻在实验结束时已没有检出.说明隆腺溞的摄食能有效控制浮游植物的生物量,可对浮游植物的群落结构产生显著影响.

Daphnia carinata is a large zooplankter in many eutrophic lakes and has a high efficiency to graze phytoplankton. The effects ofDaphnia carinata on chlorophyll-a and the community structure of phytoplankton of Lake Xuanwu in Nanjing was studied experimentally. The results showed that the density of phytoplankton decreased 83% and the chlorophyll-a decreased 81% in the Daphnia carinata treatment comparing with the control. There is no significant relationship between nitrogen, phosphorus and chlorophyll-a in the Daphnia treatment. When Daphnia presented, the community structure of phytoplankton had changed. The proportion of Cyanophyta, Chlorophyta and Bacillariophyta obviously increased and the proportion of Cryptophyta obviously decreased. The Chrysophyta, Pyrrophyta, and Euglenophyta were not found at the end of the experimentation. Our experiments showed that Daphnia carinata can efficiently control the biomass of phytoplankton and change the community structure of phytoplankton.