Study On Phytoplankton Diversity And Estimation Of Fish Production Potential During Open Water Period In Harbin Xiquanyan Reservoir

In order to study the diversity of planktonic organisms and their fish production potential in the Xiquanyan Reservoir,this paper conducted systematic sampling and monitoring of planktonic organisms and fish in the spring,summer,and autumn seasons of 2021（March May,June August,and September November）.At the same time,in-depth analysis of the population composition and quantity of plankton in the reservoir area,as well as their correlation with environmental factors,is conducted to explore the stability of the ecosystem in the Xiquanyan Reservoir area,providing a theoretical basis for ecological restoration and rational development of water resources.The main results of this study are as follows:There are 8 phyla,23 families,78 genera and 258 species of Phytoplankton in Xiquanyan Reservoir,and the largest number is Bacillariophyt.The top three dominant species in the rankings are Achnanthes exigua,Nitzschia palea,and Cylotella stelligera.The average abundance and biomass of Phytoplankton are 0.09×105cells/L and 0.15mg/L.The research results of Diversity index show that the water quality of the reservoir is mainly in the form of oligopoly,and the environmental factors affecting Phytoplankton are mainly water temperature,total phosphorus and total nitrogen.Zooplankton consists of 28 species,22 genera,11 families,2 phyla,with Cladocera being the largest.The top three on the list are Bostina longirostris,Keratella valga and Asplanchna priodonala.The abundance of Zooplankton did not change significantly in the two seasons,and the Shannon Winner Diversity index and Pielou evenness index had significant differences in summer and autumn（P<0.05）.RDA analysis shows that the main environmental factors affecting the community structure of Zooplankton in the reservoir are total nitrogen（TN）,ammonia nitrogen（NH4⁺-N）and Permanganate index(COD_Mn).There are 20 species of fish belonging to 7 families of 4 orders,with the largest number of cypriniformes.The dominant species are mainly exotic species such as Stone moroko parva,Aristichthys nobilis,Hypseleotris swinhonis and Ctenopharyngodon idella.The three Diversity index have great changes,and the overall structural stability is not strong.The environmental factors affecting the fish community structure are electrical conductivity and salinity.The production potential of silver carp and bighead carp in Xiquanyan Reservoir in 2021is 409.69 tons.The potential for fish production shows a clear seasonal fluctuation trend,with the lowest values appearing in May and then increasing month by month,and the highest values appearing from July to August;Then it gradually decreased from September to October.This study mainly analyzes the plankton diversity and fish production potential of Xiquanyan Reservoir,hoping to provide a reference basis for enriching the biodiversity of Ashi River in the Songhua River basin and maintaining the sustainable development of biology in the tributaries of the reservoir area.