不同藻密度条件下铜绿微囊藻与大型溞的相互影响

摘要

通过设置模拟摄食试验,使用铜绿微囊藻藻液及滤液对大型溞同时进行急性毒理试验,探讨了不同藻密度条件下铜绿微囊藻与大型溞之间的相互影响。结果表明,大型溞的摄食行为对铜绿微囊藻的生长有抑制,抑制作用随藻密度升高而下降,中、低藻密度(1.01×108 mL-1、1.01×107 mL-1)下的抑制率分别为54.6%、65.7%,高密度(1.01×109 mL-1)下的抑制率为29.7%。同时,铜绿微囊藻对大型溞有毒性作用,在毒理试验中,藻液组24 h和48 h的LC50值分别为0.455×107 mL-1和0.036×107 mL-1,滤液组24 h和48 h的LC50值分别为1.299×107 mL-1和0.179×107 mL-1。藻液组的LC50值明显低于滤液组,结合镜检表明,大型溞摄食铜绿微囊藻,铜绿微囊藻对大型溞的毒性影响以胞内毒素为主。在藻-溞微生态系统中,当藻密度低时,大型溞种群对铜绿微囊藻的去除效果显著,藻细胞被摄食殆尽后大型溞迅速死亡；当藻密度适中时,大型溞种群对铜绿微囊藻的去除效果良好,存活时间最长；当藻密度高时,大型溞种群受藻毒素强烈影响,短时间内死亡殆尽,对铜绿微囊藻的去除效果差。%In this paper, the mutual influence between Microcystis aeruginosa and Daphnia magna under the condition of different algal densities was discussed through the simulation feeding test and toxicology test. The results showed that the grazing behaviour of D. Magna had inhibitory effect on the growth of Microcystis aerugino-sa, and the inhibition decreased with the algal density increase. The inhibition rates were 65. 7%, 54. 6% and 29. 7% at low, medium and high algal density ( which were 1. 01 × 107 mL-1、1. 01 × 108 mL-1 and 1. 01 × 109 mL-1 respectively) . Meanwhile, Microcystis aeruginosa had toxic effects on D. Magna. In the toxicity test, the 24 h LC50 and 48 h LC50 of algae liquid group were 0. 455 × 107 mL-1 and 0. 036 × 107 mL-1 . The 24 h LC50 and 48 h LC50 of filtrate group were 1. 299 × 107 mL-1 and 0. 179 × 107 mL-1 . The half lethal concentration of the algae liquid group were significantly lower than that of filtrate group. Microscopic examination revealed that intracellular toxin tended to be the main factor for Mi-crocystis aeruginosa affecting D. Magna. In the eco-system of Microcystis aeruginosa and D. Magna, the re-moval effect of Microcystis aeruginosa by D. Magna was remarkable under the condition of low algal density.D. magna quickly died when the algal cells being eaten up. Under the condition of medium algal density, the removal effect was fine and the D. Magna survived longest. Under the condition of high algal density, D. Mag-na was strongly influenced by Microcystis aeruginosa and died out in a short period of time, the removal effect was poor.