Plankton Diversity Of Barkol Salt Lake In Xinjiang,China

The Barkol Salt Lake is a typical inland plateau lake,which is an ecological lake of the Barkol County.Due to the unique geographical location and environment climate,the salt lake is rich in mineral resources and biological resources.However,as the effects of global climate change and human activities,lake surface reduction,lake microclimate dry,even part of a seasonal lakes dried up,to narrow the lake and water quality deterioration has become a more prominent environmental problem in Hami,Xinjiang.To understand the plankton community structure in Barkol Salt Lake,and rich salt lake plankton resources,this study from 2020 to 2021,choose October 2020,May 2021 and August 2021 for the three sampling surveys in Barkol Salt Lake.A total of four sampling regions were set,and each sampling region was randomly samled from three sampling sites.Based on the traditional morphological methods and high-throughput sequencing technology,statistical analysis of salt lake plankton community species composition,density and biomass,dominant species,common species and Shannon-Wiener index,Pielous evenness index and Margalef species richness index.The differences of plankton community composition between the two identification methods were compared,and the changes of plankton community structure based on morphological identification results compared with that in the 1990s were explored.the main research results are as follows:A total of 62 genera of 7 phyla phytoplankton and 30 genera of 3 phyla including 40 species of zooplankton(expect Artemia)were identified based on the three sampling investigations of morphological identification.The species composition of phytoplankton is mainly Bacillariophyta,Chlorophyta and Cyanophyta,Zooplankton are mainly Protozoa and Rotifera;The dominant phytoplankton species all belong to Bacillariophyta,Chlorophyta and Cyanophyta,the dominant zooplankton are Arcella sp.and Keratella cochlearis.The average density of phytoplankton was 9.34×10~4 ind./L and the average biomass was 1.97 mg/L;The average density of zooplankton was 146.45 ind./L and the average biomass was 0.51mg/L;The phytoplankton Shannon-Wiener biodiversity index ranged from 0.822 to 3.509,zooplankton species ranged from 0 to 2.919.From the perspective of community structure,there were obvious seasonal variations and horizontal distribution differences.In The sampling period of May,there were more species of plankton,but the density and biomass of plankton were lower.The number of species in the inlet and center of West Lake was higher than that of the other two sampling areas,which was mainly caused by salinity fluctuation and water temperature change.Identification of all plankton samples collected in August 2021 based on high-throughput sequencing.The results showed that 16S r RNA annotated 38 phyla,538 genus and 136 species based on amplicon sequencing,of these,367(40.55%)taxa were not annotated at the genus level,the 1,510(91.74%)of the taxa cannot be annotated at the species level.18S r RNA based amplicon sequencing was annotated to 18phyla,59 genus and 23 species,of these,24(28.92%)taxa were not annotated at the genus level,the 101(81.45%)taxa could not be annotated at the species level.Prokaryotes have the highest relative abundance of Firmicutes Planococcus;eukaryon,the relative abundance of Basidiomycota Vishniaco was highest in eukaryotes(except Artemia).Overall,the Barkol Salt Lake plankton based on high-throughput sequencing are mainly micro-type(?5?m)organisms,and species annotation was poor at the species level.To identify phytoplankton and zooplankton based on traditional morphology and high-throughput sequencing techniques,10 phyla include 110 genus were identified,of which 7 phyla 14 genus were identified in both methods.Most of the species identified by morphology(66.67%)can also be identified by 16S sequencing,while most of identified by 16S sequencing(89.66%)can not be identified by morphology.Most morphologically identified species(85.96%)are not identified by 18S sequencing,and36.36%from 18S can be identified by morphology.Both identification methods correlated poorly in species composition and relative abundance.Comparing the plankton community structure of Barkol Salt Lake in the 1990s and this investigate with the traditional morphological method,the plankton community structure of Barkol Salt Lake has changed significantly in the past 30 years.In species composition,the proportion of Bacillariophyta increased,while Chlorophyta and Cyanophyta decreased.The plankton density decreased significantly(P=0.049),while the biomass increased(P=0.101).Compared with 1990s,this survey identified Cladocera and Copepoda in zooplankton,changing water environmental factors due to climate change and human activities are the main causes of this difference.The structure of plankton communities in Barkol Salt Lake was studied based on the traditional morphology and high-throughput sequencing technology.This can understand the current situation of salt lake resources,is conducive to the selection of salt-phagage species,realize the efficient utilization of salt lake resources,and provide reference materials for the scientific management of salt lake.The comparative study on plankton in Barkol Salt Lake based on two identification methods has some reference value for the selection of plankton research methods in the future.