Dynamics Changes Of Metazooplankton Community Structure And Its Response To Different TN/TP Ratio In Plateau Reservoir

(1)From March 2017 to December 2018,the dynamic changes of the metazooplankton community structure and the main environmental factors that caused dynamic changes in Plateau Reservoirs in Guizhou Province—Hongfeng Reservoir and Baihua Reservoir were investigated.Data analysis showed that:A total of 37 metazooplankton species were detected in Hongfeng Reservoir,including 23 rotifer species,4 copepoda species?genus?,10 cladocera species?genus?.A total of 36metazooplankton species were detected in Baihua Reservoir,including 23rotifer species,4 copepoda species?genus?,and 9 cladocera species?genus?.The dynamics of metazooplankton abundance and biomass at the sampling sites of Hongfeng Reservoir and Baihua Reservoir are consistent,generally occurring highest in the March-April months of spring and the September-November months of autumn.The biomass of the corresponding months also appears highest.RDA indicated that the community structure of metazooplankton community in Hongfeng Reservoir was dominated by TN,DO,EC,SD,and Chla.The community structure of metazooplankton in Baihua Reservoir was dominated by NH₄-N,COD,TN,DO,EC,WT,and Chla.Integrating the two reservoirs,it is concluded that WT,Chla,and TN can significantly affect the distribution of metazooplankton,and nutrients remain the main influence factor.?2?Through biological simulation experiments at Baihua Reservoir,based on the concentration of N and P in the original lake water,different N and P nutrients were added to adjust different TN/TP ratio,and to explore metazooplankton growth responses on different TN/TP ratio.The data analysis results show that for the simulation experiment,25metazooplankton species were detected in Baihua Reservoir during the spring,summer,autumn and winter seasons,including 19 rotiferspecies,3copepoda species?genus?,and 3 cladocera species?genus?.In the N addition group,when the TN/TP ratio of Baihua reservoirwas 4:1,metazooplankton abundance peaked.When the TN/TP ratio of Baihua reservoir was 4:1 or 16:1,metazooplankton biomass peaked.In the P addition group,when the TN/TP ratio of Baihua reservoir was 1:1,metazooplankton abundance peaked.When the TN/TP ratio of Baihua reservoir was 4:1,metazooplankton biomass peaked.From the four seasons,the addition of N and P in summer can promote the growth of metazooplankton.From abundance of each season,the addition of N is more conducive to the reproduction of metazooplankton.