The Study Of Phytoplankton Community Structure In The Western Pacific Ocean

The variation of phytoplankton community structure were investigated in the western Pacific Ocean in the autumn of 2016,2017 and 2018(September-October),and the correlation between phytoplankton community structure and environmental factors.Hope to provide some basic background information for the western Pacific and lay the foundation for future research.Samples are obtained in two ways,netz-phytoplankton(10 phytoplankton samples from 10 stations in 2016)and phytoplankton(154 phytoplankton samples from 22 stations in 2016,189 phytoplankton samples from 27 stations in 2017 and 132 phytoplankton samples from 22 stations in 2018).There are 4 phyla of phytoplankton were identified,including Bacillariophyta,Pyrrophyta,Chrysophyta and Cyanophyta.A total of 243 species of phytoplankton belonging to 66 genera and 4 phyla were identified by netz-phytoplankton in which 34 genera and 103 species belonged to Bacillariophyta,28 genera and 133 species were Pyrrophyta,2 genera and 3 species were Chrysophyta,and 2 genera and 4 species were Cyanophyta.305 species of phytoplankton belonging to 76 genera and 4 phyla were identified in 2016,339 species of phytoplankton belonging to 83 genera and 4 phyla were identified in 2017,and 269 species of phytoplankton belonging to 70 genera and 4 phyla were identified in 2018.These species were tropic oceanic and warm oceanic species mostly,which indicated that the climate of the was tropical and subtropical.In 2016,the total cell abundance of netz-phytoplankton ranged from(12.062-6892.559)×103 cell/m3,with an average of 1 965.573×103 cell/m3.In 2016,the total cell abundance of phytoplankton ranged from(0.030-423.938)×103 cell/L,with an average of 8.466x103 cell/L.In 2017,the total cell abundance of phytoplankton ranged from(0.066-498.450)×103 cell/L,with an average of 10.498×103 cell/L.In 2018,the total cell abundance of phytoplankton ranged from(0.032-719.680)×103 cell/L,with an average of 24.569×103 cell/L.The cell abundance of phytoplankton is determined by the Phytoplankton in cyanobacterium,and the maximum value appears near the equator.The cell abundance of phytoplankton after neglecting Phytoplankton is contributed by diatom and dinoflagellate.In 2016,the dominant species of netz-phytoplankton were Trichodesmium thiebautii?Prorocentrum leniculatum?Trichodesmium erythraeum?Coscinodiscus subtilis?Trichodesmium hildebrandtii?Prorocentrum compressum and so on.The dominant species in 2016 were Trichodesmium thiebaultii,Prorocentrum leniculatum,Trichodesmium erythraeum,Coscinodiscus subtilis,Trichodesmium hildebrandtii,Prorocentrum compressum and so on.The dominant species in 2017 were Trichodesmium thiebautii,Trichodesmium erythraeum,Coscinodiscus subtilis,Prorocentrum leniculatum,Trichodesmium hildebrandtii,Prorocentrum compressum and so on.The dominant species in 2018 were Trichodesmium thiebautii,Trichodesmium erythraeum,Trichodesmium hildebrandti,Pseudo-nitzschia delicatissima,Nitzschia spp.,Pseudo-nitzschia pungens and so on.In 2016 by netz-phytoplankton,2016 phytoplankton,2017 phytoplankton and 2018 phytoplankton,the average of S-W diversity was 2.440,2.941,3.200 and 2.964,and the average of Pielou evenness index was 0.163,0.363,0.368 and 0.362,respectively.Cluster analysis of phytoplankton species and their cell abundances was carried out based on the integration of 0-200 m water column at each station in each year.Cluster analysis results showed that the cell abundances of Trichodesmium thiebautii had a great influence on the similarity of cluster analysis between stations.The correlation analysis between phytoplankton and environmental factors showed that the phytoplankton at the survey station was less affected by nutrients,but more related to temperature,depth and salinity.