The Studies On Phytoplankton Diversity And Environmental In Jingpo Lake

Jingpo Lake is located in Ning'an country of Mudanjiang city of Heilongjiang Province,the Songhua River water system.The geographical coordinates are 128°07?—129°06?E,43°30?—44°20?N.It is the largest typical alpine lake in China,which is a National Nature Reserve,possessing a prominent position and prominent economic benefits in freshwater aquaculture,tourism,power,transportation,drinking water and other aspects,the water quality directly affect the safety of 2 million people who drinking the water along the downstream coast.In this study,phytoplankton were collected from 7 sampling sites of Jingpo Lake in spring,summer and autumn in 2015 and 2016,at the same time,the water environmental factors were also measured.Based on the observation and identification of phytoplankton,the species composition and cell density of phytoplankton,we discuss the seasonal succession and environmental correlation of phytoplankton community structure.Cluster analysis was used to analyze the community structure of phytoplankton,and MDS was used to investigate the similarity of phytoplankton community structure;Principal component analysis and canonical correspondence analysis were used to analyze the correlation between phytoplankton community composition and environmental factors;Diversity index was used to analyze the diversity of phytoplankton community structure in Jingpo Lake,so as to evaluate the water quality of Jingpo Lake.1.By the preliminary study of Jingpo Lake,a total of 279 taxa of phytoplankton were identified,which belonging to 8 genera,11 families,23 orders,43 families and116 genera.The community structure of phytoplankton in the Jingpo Lake was dominated by Chlorophyta and Bacillariophyta,the average cell density of phytoplankton in the two years was 2.52×10~6ind./L.The species of phytoplankton are abundant in the lake,which mainly processed by the Chlorophyta and Bacillariophyta.Affected by the environmental factors,the dominant population changed with the change of seasons and sampling points.2.The results of seven physical and chemical factors were monitored for two years in Jingpo Lake,the results showed that the average temperature is 18.62;the average value of pH was 8.56,and the water was alkaline;the average value of electrical conductivity is 113.59?s/cm;the average concentration of total nitrogen was 1.25mg/L;the average concentration of total phosphorus was 0.025mg/L;the average chemical oxygen demand was 18.65mg/L;the physical and chemical factors showed that the water of Jingpo Lake was polluted.3.Using the diversity index to evaluate the water quality of Jingpo Lake,our results showed that the average value of Margalef diversity index was 4.882,the average value of Shannon-Wiener diversity index was 1.995,the average value of Pielou evenness index is 0.628,the average value of Simpson?s ecological dominance index is 0.746,the average value of diversity threshold was 3.266.Comprehensive evaluation results showed that the diversity of phytoplankton in Jingpo Lake is good,the community structure is stable,and the water body is in the state of moderate pollution.4.Based on cluster analysis and multidimensional scaling analysis of phytoplankton community structure,the results showed that the community structure of phytoplankton was different among sampling sites.In the MDS sequencing analysis,all stress index values were less than 0.2,which indicated that MDS can well explain the similarities of phytoplankton communities between different sampling sites.5.The relationship between phytoplankton and environmental factors in Jingpo Lake were detected by principal component analysis and canonical correspondence analysis.The results showed that water temperature,conductivity,pH and total nitrogen were the main environmental factors affecting the changes of phytoplankton community structure in Jingpo Lake.