鲴对食微囊藻鲢鳙排泄物及藻活性的作用研究

Effect of Xenocypris microlepis on feces and microcystis activity from microcystis-dietary silver carp and bighead carp

开展室内模拟实验,研究鲢、鳙和鲴不同混养系统中排泄物的量及微囊藻活性的变化.实验设置鲢鳙组合,鲢鳙鲴组合以及对照组,其中鲢鳙生物量放养比例为3:1,鲢鳙鲴组合中生物量放养比例为3:1:1,实验周期14d.结果显示,鲢鳙组和鲢鳙鲴组均能降低微囊藻密度,两组无显著差异(P>0.05),但是均极显著小于对照组(P<0.01).混养鲴鱼可以降低排泄物的量及微囊藻的被消化率,鲢鳙鲴组排泄物的量在第4d开始下降,实验结束时是鲢鳙组的16.08%.鲢鳙鲴组微囊藻的被消化率,第5d后快速增长,至实验结束达到85.9%,极显著高于鲢鳙组(P<0.01).鲢鳙组和鲢鳙鲴组排泄物中的氨基酸和总氮含量相比未被摄食微囊藻减少率分别为33.17%、53.62%和34.97%、54.27%.鲢鳙鲴组和鲢鳙组排泄物光能活性(Fv/Fm、Fv/Fo、Yeld、q P及NPQ表示)和生长活性差异(EPS、Chla表示)较大,鲢鳙组微囊藻叶绿素荧光参数(除NPQ外)值经过短暂的下降后开始增长,而鲢鳙鲴组Fv/Fm、Fv/Fo、Yeld及q P在培养过程中下降显著,且至第5d后叶绿素荧光参数(除NPQ外)均极显著低于鲢鳙组(P<0.01).鲢鳙鲴组NPQ呈上升的趋势,且第7d后极显著高于鲢鳙组(P<0.01).在排泄物培养期间,鲢鳙鲴组排泄物中微囊藻的胞外多糖(EPS)含量、叶绿素a(Chl a)浓度不断下降,至实验结束极显著低于鲢鳙组(P<0.01).结果表明,在鲢鳙控藻的基础上,混养鲴鱼可以减少鲢鳙摄食微囊藻后的排泄物,同时降低排泄物中微囊藻活性,减少了因鲢鳙排泄物引起的水环境污染和生态影响.

Effects on the amounts of feces and the activity of microcystis by the introduction of the different combinationof Silver carp,bighead carp and Xenocypris microlepis were studied in indoor simulation experiments.During theexperiment,three groups were set up:silver carp and bighead carp group,silver carp、bighead carp and Xenocyprismicrolepis group,blank control group,and the biomass proportion of silver carp and bighead was carp3:1.The resultsshowed that in both experimental groups,the densities of Microcystis aeruginosa were significantly reduced than blankcontrol group(P<0.01).The feces weight in silver carp and bighead carp group continually increased,however,which ofpolyculture of Xenocypris microlepis group reached maximum on the4th day,then declined rapidly,and finally was16.08%of silver carp and bighead carp group at the end of the experiment.There were no obvious change in algaedigestibility in silver carp and bighead carp group,while the algae digestibility of the polyculture of Xenocypris microlepisgruoup appeared rapid growth from5th day,reached85.9%at the end of the experiment,which was significantly higherthan the silver carp and bighead carp group(P<0.01).The amino acid and nitrogen content in the feces of experimentalgroups decreased compared with those undigested Microcystis aeruginosa:the decrement in silver carp and bighead carpgroup were33.17%and53.62%and those in polyculture of Xenocypris microlepis were34.97%and53.62%,respectively.Furthermore,after Microcystis aeruginosa was digested by fish,chlorophyll fluorescence parameters(except NPQ)wassignificantly lower than the blank control group(P<0.05),but NPQ was significantly higher than the blank control group(P<0.05).Chlorophyll fluorescence parameters(except NPQ)in silver carp and bighead carp group increased after a brief decreasing.Fv/Fm、Fv/Fo、Yield and qP values in polyculture of Xenocypris microlepis group early rapidly declined at first,tended to be stable after the11day,and5days later were significantly lower than that of silver carp and bighead carp group(P<0.01).NPQ in polyculture of Xenocypris microlepisgroup showed ascendant trend,and then was significantly higher thanthat of silver carp and bighead carp group after the7th day(P<0.01).During the feces cultivation,the EPS and Chla of fecesin polyculture of Xenocypris microlepis group continually decreased,and until the end of the experiment,they wassignificantly lower than those of silver carp and bighead carp group(P<0.01).Beside the introduction of silver carp andbighead carp,the polyculture of Xenocypris microlepis could reduce the feces of silver carp and bighead carp by feedingMicrocystis aeruginosa and further reduce the activity of the algae in feces therefore,improved the removal effect caused byMicrocystis aeruginosa,provided theoretical basis for biomanipulation mode of polyculture of Xenocypris microlepis.