Dynamic Changes Of Plankton In Harbin Xiquanyan Reservoir During The Frozen Period

Taking Xiquanyan Reservoir as the research object,this study conducted four surveys and samples of the subglacial water body in December 2021,January,February and March 2022,and mastered the species composition,spatial and temporal distribution,biodiversity and the change characteristics of physical and chemical factors of the plankton in detail.Then,the correlation between plankton community structure and environmental factors during the frozen period of the reservoir was analyzed by one-way ANOVA,redundancy analysis(RDA)and other statistical methods,and the influencing mechanism of plankton community structure characteristics was discussed,in order to provide data support and theoretical basis for relevant environmental protection departments,which is of great significance for the establishment of effective management and protection measures.The main results of this paper are as follows:1.A total of 205 species of phytoplankton were identified from 8 phyla,102 genera,including 115 species of chlorophyta 52 genera,37 species of Diatom 22 genera,17 species of Gymnophyta 4 genera,13 species of cyanophyta 11 genera,8 species of Cryptophyta 2 genera,8 species of Chrysophyta 5 genera,4 species of Dinoflagellata 3 genera,and 3 species of Xanthophyta 3 genera.During the ice period,the phytoplankton were of green algae-diatom type,and the replacement rate of dominant species was 14.29% from December to January,16.67% from January to February,and 44.44% from February to March.The species richness,density and biomass of phytoplankton decreased steadily with the continuation of the glacial period.The Shannon-Wiener diversity index and Margalef richness index(d)of phytoplankton showed the trends of December 2021 > January 2022 > February 2022 > March 2022.The Simpson dominance index(D)showed a trend of December 2021 > January 2022 > March2022 > February 2022,and the Pielou evenness index(J)showed a pattern of March 2022 >February 2022 > December 2021 > January 2022.2.A total of 177 species of zooplankton were identified,including 87 species of protozoa,65 species of rotifers,13 species of copepods and 12 species of cladicornis.The proportion of cladoceras and copepods changed little,and the proportion of protozoa gradually increased.The replacement rate of dominant zooplankton species was 50% from December to January,50% from January to February,and 28.57% from February to March.The species richness,density and biomass of zooplankton decreased steadily with the continuation of the glacial period.Shannon-Wiener Diversity Index(H ’)and Margalef richness index(d)showed the trends of December 2021 > January 2022 > February 2022 > March 2022.The Simpson dominance index(D)showed a trend of December 2021 > January 2022 > March 2022 >February 2022,and the Pielou evenness index(J)showed a pattern of March 2022 > February2022 > January 2022 > December 2021.3.With the continuation of the freezing period,factors such as IT,NH4+,TN,TP and SD show a trend of increasing,while COD,DO,Chl-a,WD and PH show a trend of decreasing,EC has no significant change,WT shows a trend of March > February > December > January,which is consistent with the change trend of external ambient temperature.The higher the water temperature.It is necessary to conduct comprehensive analysis and evaluation to evaluate the water quality of the subglacial water body during the glacial period.DO was the most influential factor on phytoplankton density in December,PH was the most influential factor on phytoplankton density in January,COD was the most influential factor on phytoplankton density in February,and SD was the most influential factor on phytoplankton density in March.IT was the most influential factor on zooplankton density in December,January and February,and Chl-a was the most influential factor on zooplankton density in March.