Study On Correlation Between Plankton Community And Environmental Factors In Hulanhe Wetland

Wetland ecosystem is an ecosystem at the intersection of land and water.It has high biological productivity and good water storage performance.It can purify water sources,store floods and resist drought,promote siltation and protect beaches,and provide a good habitat for wildlife.Hulanhe Wetland is located in the north bank of Songhua River in Harbin,Heilongjiang Province,Hulan River.The average altitude is116 meters.Affected by the temperate monsoon climate,the climate is distinct.It has excellent natural wetland ecosystem and high biodiversity.It belongs to the wetland under restoration and construction.In this study,plankton samples were collected and identified at 12 sampling sites in Hulanhe Wetland from April to August and October 2021,and the physical and chemical indicators of the water were measured.According to the information of the China Remote Sensing Data Network and the field observation during the field sample collection period,Hulanhe wetland is divided into five functional areas(farmland affected area,fishing affected area,wetland protection area,inlet area and outlet area).This study analyzed the temporal and spatial changes of phytoplankton species composition,abundance,dominant species and environmental factors in Hulanhe Wetland,the correlation between phytoplankton and zooplankton,and the driving factors of phytoplankton community stability.The main results are as follows:(1)The ecological type of water body in Hulanhe Wetland is diatom-green algae type water body.A total of 209 taxonomic units were identified,belonging to 8 phyla,11 classes,22 orders,42 families,91 genera,of which diatoms were the most,followed by Chlorophyta,and then Cyanophyta.The number of other phytoplankton species is relatively small;a total of 90 species of zooplankton belonging to 4categories were identified in Hulanhe Wetland,among which rotifers were the most,followed by protozoa,copepods and cladocerans accounted for less.The spatial and temporal distribution of phytoplankton was significantly different,and the spatial and temporal distribution of zooplankton was not significant.A total of 39 taxa of phytoplankton dominant species and 18 taxa of zooplankton dominant species were found in 2021,among which Chlorophyta,Cyanophyta,Bacillariophyta,Rotifera and Protozoa species were more,and the dominant species had certain heterogeneity among different regions.(2)During the survey in 2021,the four diversity indexes of Margalef diversity index(H),Shannon-Wiener diversity index(H’),Pielou evenness index(J)and Simpson ’s ecological dominance index(D)had significant spatial and temporal distribution characteristics.The average value of the three seasons was the highest in summer,and the wetland protection area in each region was significantly higher than that in other regions,indicating that the individual distribution of plankton was relatively uniform,the automatic adjustment ability was relatively strong,and the community structure was relatively stable.It can be seen from the analysis of various indexes that Hulanhe Wetland is basically in a state of light pollution to moderate pollution during the study period of 2021.The comprehensive comparison shows that it is feasible to evaluate the water quality by using various species diversity indexes.(3)The phytoplankton resource utilization efficiency(RURpp)and zooplankton resource utilization efficiency(RUEzp)in Hulanhe Wetland have significant spatial and temporal distribution characteristics.The resource utilization efficiency in summer is much higher than that in spring and autumn,and the resource utilization efficiency in wetland protection area is much higher than that in inlet and outlet area.The least squares(OLS)regression equation test showed that the plankton community turnover index was significantly negatively correlated with RUE,indicating that the plankton community with high resource utilization rate often had stronger stability and stronger adaptability to the environment.(4)The stability of plankton community in Hulanhe Wetland is regulated by multiple factors.Among them,the stability of plankton community had a significant linear relationship with Margalef diversity index,Pielou evenness index and RUE.The key factors affecting the stability of phytoplankton community in Hulanhe Wetland were WT and p H.The stability of zooplankton community was mainly driven by WT,p H and TN.(5)The community structure and succession of phytoplankton and zooplankton in Hulanhe Wetland were closely related to environmental factors during the study period.Redundancy Analysis(RDA)showed that the main environmental variables driving the succession and distribution of phytoplankton and zooplankton communities in Hulanhe Wetland in 2021 were WT,p H,TN and WT,p H,respectively,which indicated that the community structure and succession of plankton in the study area were affected by the synergistic effect of various environmental factors.