Spatial And Temporal Variation Characteristics And Driving Factors Of Plankton Community In Weishan Lake

Weishan Lake,one of the regulation and storage lakes of South-to-North Water Diversion,has its ecological environment being one of the focuses of people's attention.Phytoplankton is the foremost imperative essential producer and sensitive biomarker in the water ecosystem,It is of incredible noteworthiness to consider the community structure of plankton and its correlation with environmental factors for solving the challenges of water resources utilization and ecological protection in Weishan Lake.In accordance with phytoplankton,zooplankton and total phosphorus?TP?,chemical oxygen demand?CODMn?,pH,suspended matter?SS?,Chlorophyll a?Chl-a?,SD,ammonia nitrogen?NH3-N?,total nitrogen?TN?,dissolved oxygen?DO?,total dissolved solids?TDS?,and salinity data,as well as chlorophyll a in 8 sampling points of Weishan Lake from September 2018 to September 2019,this study has analyzed the temporal and spatial characteristics of the plankton community in Weishan Lake and explored the relationship between them and natural components.The most comes about are as follows:?1?During the study period,points 6,7 and 8 represented the most serious pollution in the southwest Lake area,and many indicators of CODMn,pH,TN and NH3-N were higher than those of other sampling points.Meanwhile,points 2 represented a higher number of indicators of COD_Mn,pH,TN and NH₃-N in the North Lake area.However,the maximum TP concentration appeared in the southeast Lake area represented by points 4 and 5.In terms of seasonal distribution,the comprehensive water quality in spring 2019 is better,the COD_Mnn in summer does not meet the class III water quality standard,and the comprehensive water quality does not meet the functional zoning objectives.?2?8 phyla and 166 species were identified,including Bacillariophyta,Chlorophyta,Cyanophyta,Cryptophyta,Euglenophyta,Chrysophyta,Pyrrophyta and Xanthophyta.Among them,68 species of Chlorophyta accounted for 41%.During the investigation,the phytoplankton density of Weishan Lake varied from 310.09×102 to 11288.26×104cells/L,with the average density being 3293.95×10⁴cells/L,the biomass varying from 2.7mg/L to106.2mg/L,the average being 28mg/L.The most prevailing species of phytoplankton are Oscillatoria tenuis,Pseudanabaena mucicola,Merismopedia tenuissima,Chroococcus minutus,Melosira granulata,Synedra acus,Melosira varians,Fragilaria capucina and Scenedesmus quadricauda.Shannon Weiner differing qualities list extend is 0.502?4.232,with the average of 2.461,Pielou evenness index range of 0.108?0.879,and the average being 0.529.?3?4 phylum and 64 species of zooplankton were detected,including Protozoa,Rotifera,Cladocera and Copepoda.Among them,the number of Rotifer species takes up the most,30species in total,accounting for 46.88%.The density range of zooplankton is 75-601cells/L,with the average density being 331.875cells/L.The floating range of zooplankton biomass is 0.23-2.9mg/L,with the average biomass being 1.48mg/L.Shannon Weiner diversity index range is 1.95?3.9,with the average value being 2.95,evenness index range being0.49?0.93,and the average value being 0.75.The dominant species of rotifers in Weishan Lake are mainly Bosmina longirostris,Simocephalus vetulus,Mesocyclops leuckarti and Nauplii.As for the dominant species of protozoa,Tintinnopsis wangi,Difflugia avellana,difflugia corona are the most common.The dominant species of Cladocera are mostly Bosmina longirostris and simocephalus vetulus.The most common species of Copepoda are Mesocyclops leuckarti and nauplii.?4?Based on the redundancy analysis of phytoplankton and zooplankton density and water environment factors,the results show that:TP,COD_Mn,Chl-a and SD are the environmental factors that have a great influence on phytoplankton density.The density of cyanobacteria and dinoflagellate is positively correlated with Chl-a,and the density of green algae is obviously affected by COD_Mn,with the density of green algae being also affected by water temperature.The density of naked algae is positively correlated with SS,with the density of diatom being positively correlated with TP.TP,COD_Mn,DO,SD and water temperature are the main environmental factors affecting the density of zooplankton.The density of Cladocera and protozoa has a significant positive correlation with TP and a negative correlation with SD.