Community Characteristics And Biodiversity Analysis Of Phytoplankton In Five Lakes Of Haihe River Basin

There are five important wetlands,Qili Sea,Beidagang,Nandagang,Baiyangdian Lake and Hengshui Lake,in the Haihe River Basin,referred to as "Five lakes".The "Five lakes" wetlands are rich in biological resources,which have played an important role in regulating the local climate and water cycle,as well as the habitat and reproduction of various aquatic organisms and birds.As an important ecological resource in North China,Five lakes is supplying not only water to surrounding agriculture and industry,but also ecological and domestic water to the urban area.As important wetlands system in the Haihe River Basin,meanwhile,they play an irreplaceable part in water purification and ecological restoration.However,in recent years,great changes taken place,biodiversity gradually decreased and showing an unhealthy community state due to water bodies being developed in the direction of eutrophication as the rapid development of the local economy,a large amount of domestic,industrial sewage,and non-point source pollutants are discharged through rivers or directly.In order to comprehensively evaluate the pollution degree of the Five lakes in the Haihe River Basin to provide basic data support for wetland pollution control,and to respond to the national "Beijing-Tianjin-Hebei Synergistic Development Planning Outline",the "Beijing-Tianjin-Hebei Synergistic Development Six Rivers and Five lakes Comprehensive Management and Ecological Restoration Overall Plan".In this paper,phytoplankton samples were collected from 16 stations in the Five lakes of the Haihe River Basin at 6 different months in 2018.After some works,identification and classification,the community structure analysis,biodiversity survey,clustering,and MDS analysis were done,the water quality of the Five lakes in the Haihe River Basin was evaluated.The results are as follows:1.According to the investigation and anlysis,a total of 114 species belong to 7phylums of phytoplankton were identified in the Five lakes of the Haihe River Basin in 2018.Cyanophyta accounts for 15.79% of total species,Cryptophyta accounts for3.51%,Pyrrhophyta accounts for 4.39%,Chrysophyta accounts for 1.75%,Baccillariophyta accounts for 35.09%,Euglenophyta accounts for 6.14%,and Chlorops accounts for 33.33%.Baccillariophyta and Chlorops took a dominant in Phytoplankton species,followed by Cyanophyta and Euglenophyta,and less or no Cryptophyta,Chrysophyta and Pyrrhophyta.2.The phytoplankton abundance of the Five lakes in the Haihe River Basin in2018 ranged from 2.77×108 ind./L to 1.30×109 ind./L,with an average of 1.01×109 ind./L.The highest abundance of phytoplankton was 1.30×109 ind./L in July,followed by 1.28×109 ind./L in September,1.15×109 ind./L in November,and 1.04×109 ind./L in May,1.02×109 ind./L in March;the least in January,2.77×108ind./L.Based on the abundance of algae: the abundance of phytoplankton was dominated by cyanobacteria 5.46 × 109 ind./L,followed by Chlorops 2.87 × 108 ind./L and Baccillariophyta 2.65 × 108 ind./L,Euglenophyta 2.83 × 107 ind./L,Cryptophyta 2.22×107 ind./L,Chrysophyta 6.05×106 ind./L,Pyrrhophyta was the least,1.34×106 ind./L.3.Using three biodiversity indices to evaluate the water quality of the Five lakes in the Haihe River Basin,the results showed that the Shannon-Wiener diversity index ranged from 0.27 to 3.64,with an average of 1.65;the Pielou uniformity index ranged from 0.07 to 0.75,with an average of 0.37;Margalef richness index ranged from 1.59 to 5.50,with an average of 2.91.Based on the biodiversity index evaluation criteria,the water quality of the Five lakes in the Haihe River Basin was generally in the middle level of pollution,the nutrition status of the wetland water was generally at the eutrophic level in 2018.4.Cluster analysis revealed that the phytoplankton community structure in the Five lakes of the Haihe River Basin in 2018 had the high similarity.MDS analysis divided 16 sampling points into 4 groups.Through the investigation of the phytoplankton community structure,distribution characteristics,and biodiversity characteristics of the Five lakes in the Haihe River Basin,the water quality and nutritional status of the Five lakes in the Haihe River basin can be reflected in a more comprehensive and objective manner,which will provide a certain data foundation for the subsequent construction and long-term maintenance of healthy aquatic ecosystems in the Haihe River Basin.