Study On The Relationship Between The Dynamic Change Of Fatty Acids In Plankton And Eutrophication Of Plateau Reservoir In Guizhou

To understand the relationship between phytoplankton,zooplankton community structure,fatty acid distribution characteristics and eutrophication of the Guizhou Plateau Reservoir,the Hongfeng Reservoir,Baihua Reservoir and Aha Reservoir were conducted once a month from August 2018 to July 2019.Sampling survey.The dynamics of phytoplankton and zooplankton community structures in the three reservoirs were clarified,and the relationship between fatty acids and eutrophication was analyzed.At the same time,in order to further explore the relationship between plankton fatty acids and eutrophication of water bodies,an indoor simulation experiment was conducted in September2019.The results of the study showed that:A total of 78 species(genus)of phytoplankton were detected in Hongfeng Reservoir,which belonged to Cyanophyta,Chlorophyta,Bacillariophyta,Pyrrhophyta,Dinophyta,Euglenophyta,and Chrysophyta.A total of 54 species(genus)of phytoplankton were detected in Baihua Reservoir,which is the same as the algae species in Hongfeng Reservoir.A total of 48 species(genus)of phytoplankton were detected in the Aha Reservoir,which belonged to Cyanophyta,Chlorophyta,Bacillariophyta,Dinophyta,Euglenophyta,Pyrrhophyta.Among the three reservoirs,the total number of species of Chlorophyta isthe largest,followed by diatom,Cyanophyta,Euglenophyta,and Dinophyta,and the total number of Cryptophyta and Chrysophyta is the least.During the survey period,the Hongfeng Reservoir was of Bacillariophyta-Cyanophyta-Chlorophyta type,Baihua Reservoir was of Chlorophyta-Bacillariophyta-Cyanophyta-Dinophyta type,and the Aha reservoir was of Bacillariophyta-Dinophyta-Bacillariophyta-Cyanophyta.44 species(genus)of zooplankton were detected in Hongfeng Reservoir.A total of 38 species(genus)of zooplankton were detected in Baihua Reservoir.A total of 33 species(genus)of zooplankton were detected in the Aha reservoir.Rotifers are the most common among the three reservoirs,followed by cladocerans and finally copepods.The percentage distribution of 13 fatty acids in phytoplankton in the three reservoirs is as follows: SFA(C16:0,C18:0,C20:0)has the highest percentage of saturated fatty acids(100%),followed by single unsaturated fatty acid MUFA(C16:1,C18:1,C20:1),and finally PUFA(C16:2,C18:2,C18:3,C20:2,C20:3,C20:4,C20:5,C22:6);zooplankton 13 The distribution of the percentage content of the three kinds of fatty acids is that SFA(C16:0,C18:0,C20:0)has the highest percentage content,which is the decrease of MUFA(C16:1,C18:1,C20:1)of single unsaturated fatty acid,Polyunsaturated fatty acids PUFA(C16:2,C18:2,C18:3,C20:2,C20:3,C20:4,C20:5,C22:6)increased.Phytoplankton fatty acid: The order of phytoplankton fatty acidcontent at different sampling points in Hongfeng Reservoir is: SFA:Jiangjun Wan(JJW)>Houwu(HW)>Huayu Dong(HYD),MUFA: HYD>JJW>HW,PUFA: JJW> HYD>HW.The order of phytoplankton fatty acid content at different sampling points of Baihua Reservoir is:SFA: Huaqiao(HQ)>Yanjiao Zhai(YJZ),MUFA: HQ>YJZ,PUFA: YJZ>HQ.Fatty acid content change of phytoplankton in the sampling point of Aha Reservoir: SFA>PUFA>MUFA;the order of fatty acid content of phytoplankton at different sampling points in Hongfeng Reservoir is:SFA: HW>JJW>HYD,MUFA: HYD>HW>JJW,PUFA: HYD>JJW>HW.The order of zooplankton fatty acid content at different sampling points in Baihua Reservoir is: SFA: HQ>YJZ,MUFA: HQ>YJZ,PUFA:YJZ>HQ.Changes in fatty acid content of zooplankton in the sampling points of Aha reservoir: PUFA>SFA>MUFA.Correlation analysis of phytoplankton fatty acids and water eutrophication index: Except for total phosphorus(TP)in Hongfeng Reservoir,there is no correlation with any fatty acids,and the remaining4 eutrophication indexes are negatively correlated with fatty acids.Baihua Reservoir TP,permanganate(CODMn)and chlorophyll-a(Chla)showed a positive correlation with fatty acids,while total nitrogen(TN)and transparency(SD)had no correlation with fatty acids.Only total TP in Aha Reservoir is positively correlated with fatty acids.Correlation analysis of zooplankton fatty acids and watereutrophication index: TN,TP,CODMn,Chla and SD in Hongfeng Reservoir and Baihua Reservoir are correlated with fatty acids.In Aha Reservoir,only TN,Chla and SD are negatively correlated with fatty acids.The selected algae species in the simulation experiments detected 6types of fatty acids in Chlorella ellipsoidea and 7 types of fatty acids in Microcystis aeruginosa.Neither C20:5(EPA)nor C22:6(DHA)were detected.With the addition of Chlorella ellipsoidea and Microcystis aeruginosa at the same concentration and different volumes,the zooplankton bio-abundance showed a downward trend from the first day of the experiment to the fourteenth day of the experiment.The zooplankton abundance of Microcystis aeruginosa decreased rapidly and the biological species gradually became single.The zooplankton community structure in the eutrophic state is more unitary.