Seasonal Dynamics Of Plankton Community Structure And Diversity In Fujin National Wetland Park

Wetlands are important ecosystems,and forests,oceans and synthesis of the Earth’s three major ecosystems,has the reputation of the Earth’s kidney,but also an important"species gene pool",but in recent years with the rapid development of cities,population resources,environmental pressure and other irrational use of the problem,resulting in a sharp decline in wetland area,ecological function decline negative impact.The rate of wetland loss in the Sanjiang Plain is high,and the work of returning wetlands to farming has been carried out successively,but due to the restoration technology and management problems,there is an urgent need to carry out long-term monitoring of the restoration process of degraded wetlands.In this study,the study area is the Fujin National Wetland Park,which is located in the southwestern part of Fujin City,Heilongjiang Province,a typical freshwater marsh wetland of the Sanjiang Plain with a total protected area of 2200 hm²,and is a typical degraded wetland park.The authors set up five areas in the Fujin National Wetland Park:the park entrance sampling site,the inlet sampling site,the internal sampling site,the backwater ditch sampling site,and the outlet sampling site,with four sampling sites in each area.A total of 20 sampling sites will be used to collect and identify plankton samples in September 2021（autumn）,May2022（spring）and July 2022（summer）,and to evaluate the water quality of the Fujin National Wetland Park by conducting plankton diversity analysis.A total of 148 species of phytoplankton in 59 genera from 7 phyla were identified in this survey,with the phylum Green Algae and Diatoms dominating.There were seasonal significant differences in phytoplankton abundance,which was mainly influenced by water temperature.Spatially,the abundance of phytoplankton varied significantly between the inlet and outlet of the park.Fifty-one species of zooplankton in 20 genera of three categories were identified,with rotifers as the main species.Spatially,the highest number of zooplankton species was found at the sample sites of the retreat ditch,and the lowest number of species was found at the sampling sites of the outlet.During the survey period,the dominant species shared by the three seasons was Merism opedia minima（cyanobacteria）;the dominant zooplankton species were three species in total,and the dominant species in spring,summer and autumn were Microcyclops varicans,Mesocyclops leuckarti and nauplius.The phytoplankton and zooplankton diversity indices differ in time as well as in spatial distribution.The water quality of the wetland park wasβ-medium polluted when phytoplankton diversity was evaluated for water quality andα-medium polluted for water bodies when zooplankton was evaluated for water quality.The physicochemical factors affecting the abundance of phytoplankton were water temperature（WT）,total nitrogen（TN）,permanganate(COD_Mn),ammonia nitrogen（NH₄-N）,and transparency（SD）;the physicochemical factors affecting the abundance of zooplankton were water temperature（WT）and ammonia nitrogen（NH₄-N）.