Study On Plankton Biodiversity And Water Environmental Characteristics Of Meishe River National Wetland Park In Haikou

Meishe River National Wetland Park is located in the northern part of Hainan Province,in Longhua District,Haikou City.It is one of the tropical freshwater wetlands that flow through multiple reservoirs.Meishe River National Wetland Park has abundant natural resources and excellent environmental regulation capabilities,and plays an important ecological role in protecting biodiversity and regulating Hainan's climate.However,the rapid development of cities and tourism in recent years has gradually deteriorated the aquatic ecological environment of the Meishe River National Wetland Park.Plankton is a collective term for phytoplankton and zooplankton.Phytoplankton plays the role of primary producer in the water ecosystem and is the basis for the productivity of other aquatic organisms in the water ecosystem.zooplankton plays the role of primary consumers in the water ecosystem,it is an important part of material transfer and energy flow in aquatic ecosystems.Therefore,plankton plays an important role in aquatic ecosystems.In order to explore the characteristics of the plankton community in the Meishe River National Wetland Park and its relationship with environmental factors,this study set up 5 sampling points in the Meishe River National Wetland Park in accordance with the lake survey specifications,and they were respectively conducted in 2019.The plankton community and water quality surveys were conducted in the Meishe River Wetland Park in March(spring),June(summer),September(autumn),and December(winter).The statistical analysis results showed that:1.There are significant seasonal differences in WT,TN and DO of the water in Meishe River National Wetland Park.The comprehensive nutritional status index method of the water was used to evaluate the quality of water in Meishe River National Wetland Park.The results showed that the comprehensive nutritional status of the water quality of1#in Meishe River National Wetland Park was oligotrophic,and the water quality comprehensive nutritional status of other sites appeared eutrophy.2.During the research and investigation period,Meishe River National Wetland Park identified 218 species of phytoplankton in 8 phyla,41 families,96 genera,and the main species composition is Chlorophyta and Diatoms,including 84 species of Chlorophyta and65 species of Diatoms,38 species of Cyanophyta,6 species of Cryptophyta,5 species each of Dinophyta and Euglena,4 species of Xanthophyta,and 2 species of Chrysophyta.Number of species:spring(109 species)>winter(78 species)>summer(66species)>autumn(52 species).The density of phytoplankton varies between 2.19×10⁷-1.38×10⁹cells/L,and the annual average density is 4.16×10⁸cells/L.It shows a changing trend of summer>winter>spring>autumn.Among them,the density of cyanobacteria and diatoms is higher in spring and summer,and the density of cyanobacteria and chlorophyta is higher in autumn and winter.The phytoplankton biomass varies from 4.12 mg/L to 58.21mg/L,and the annual average biomass is 25.78 mg/L,showing a trend of summer>winter>spring>autumn,Among them,the four seasons of spring,summer,autumn and winter are diatoms with the largest biomass.There are 19 dominant species of phytoplankton in the four seasons,including Diatom,Cyanophyta and Chlorophyta,The Cyclotella sp.are the dominant species of phytoplankton with the highest frequency in all seasons.3.During the survey period,the Shannon-Wiener diversity index H'of the phytoplankton community in Meishe River National Wetland Park varied from 1.33-2.35,and the annual average of H'is 1.86,spring>winter>autumn>summer.The Pielou evenness index J'varies from 0.41 to 0.66,and the annual average of J'is 0.58,spring>autumn>winter>summer.The variation range of Margalef species richness index D'is 1.18-3.56,and the annual average of D'is 2.02,spring>winter>summer>autumn.The diversity threshold D_Vranged from 2.72-3.56,and the annual average of D_Vis 3.23,spring>summer>winter>autumn.The seasonal changes of the diversity indexes are obvious,and the biodiversity indexes are higher in spring,and the stability of the ecosystem is better.4.Redundant analysis(RDA analysis)between the water environmental factors and the dominant species density of the phytoplankton community shows that the main water environmental factors affecting the dominant species of the phytoplankton community are Chl-a,COD,S,SD,DO,and WT.5.During the research and investigation period,Meishe River National Wetland Park identified 4 types of zooplankton,43 families,63 genera and 134 species,including 5unspecified species and 3 larvae.Among them,rotifers are the most species,with 53species,38 protozoa,28 cladocerans,and 15 copepods.The number of species is spring(55 species)>winter(43 species)>summer(38 species)>autumn(26 species).The density of zooplankton varies between 111.21-534.49 ind./L,and the annual average density is234.52 ind./L.Shows a changing trend of winter>autumn>summer>spring.Among them,the density of rotifers and copepods is higher in spring,and the density of protozoa and rotifers is higher in summer,autumn and winter.The change range of zooplankton biomass is between 0.097 mg/L-0.168 mg/L,and the annual average biomass is 0.122 mg/L,showing a changing trend of winter>spring>summer>autumn.Among them,copepods have the highest biomass in spring,and rotifers have the highest biomass in summer,autumn and winter.There are 14 dominant species of zooplankton in the four seasons,including rotifers,protozoa,and copepods.The most frequent occurrence of the dominant species of zooplankton in all seasons is the unspecified ciliates in the protozoa.6.During the survey period,the Shannon-Wiener diversity index H'of the zooplankton community in Meishe River National Wetland Park varied from 1.40 to 2.13,with an annual average of 1.72,spring>summer>winter>autumn.The Pielou evenness index J'varies from 0.64-0.78,with an annual average of 0.73,spring>winter>summer>autumn.The range of Margalef species richness index D'is3.30-10.84,the annual average is 5.9,summer>spring>winter>autumn.The diversity threshold D_Vranged from 1.72 to 2.78,with an annual average of 2.28,spring>summer>winter>autumn.The seasonal changes of the diversity indexes are obvious,and the biodiversity indexes are higher in spring and summer,and the stability of the ecosystem is better.7.Redundant analysis(RDA analysis)between the water environmental factors and the dominant species density of the zooplankton community shows that the main water environmental factors affecting the dominant species of the zooplankton community are Chl-a,COD_Mn,p H,TP,TN,S,SD.