Seasonal dynamics of photosynthetic picoeukaryote abundance and diversity in the Yellow Sea and East China Sea

Abstract

Background: Marine photosynthetic picoplanktons, cell size less than 3 um, contribute significantly to phytoplankton biomass and perform essential ecological roles in vast marine area. Compared with photosynthetic picoprokaryotes(PPPs) dominated by two genera, Prochlorococcus and Synechococcus, photosynthetic picoeukaryotes(PPEs)are much more diverse, with virtually every algal class being represented. Despite importance of PPEs, the true extent of their diversity and composition has only recently been uncovered by molecular methods. However, the genetic diversity and ecology of PPEs are still poorly described for the Yellow Sea and the East China Sea.Results: Surface water samples were collected from the YS and ECS, and analyzed for PPEs cell abundance and genetic diversity. PPEs cell abundance enumerated using flow cytometry, showed seasonal variations ranging 102~105 cells ml-1. PPEs genetic diversity was analyzed using Illumina MiSeq sequencing of Plastid 16S rRNA gene amplicons. At the division level, the most abundant PPEs were Chlorophyta and Haptophyta, followed by Ochrophyta, Crytophyta, and Dinophyta. In the East China Sea, relative abundance of Chlorophyta group to total PPEs showed seasonally variable contribution of 7.3~755.7%, and mostly dominated by Mamiellopphyceae and Prasionophyceae. However, in the Yellow Sea, Haptophyta was the most abundant group dominated by Prymnesiophyceae. nated by two genera, Prochlorococcus and Synechococcus, photosynthetic picoeukaryotes(PPEs)are much more diverse, with virtually every algal class being represented. Despite importance of PPEs, the true extent of their diversity and composition has only recently been uncovered by molecular methods. However, the genetic diversity and ecology of PPEs are still poorly described for the Yellow Sea and the East China Sea.Results: Surface water samples were collected from the YS and ECS, and analyzed for PPEs cell abundance and genetic diversity. PPEs cell abundance enumerated using flow cytometry, showed seasonal variations ranging 102~105 cells ml-1. PPEs genetic diversity was analyzed using Illumina MiSeq sequencing of Plastid 16S rRNA gene amplicons. At the division level, the most abundant PPEs were Chlorophyta and Haptophyta, followed by Ochrophyta, Crytophyta, and Dinophyta. In the East China Sea, relative abundance of Chlorophyta group to total PPEs showed seasonally variable contribution of 7.3~755.7%, and mostly dominated by Mamiellopphyceae and Prasionophyceae. However, in the Yellow Sea, Haptophyta was the most abundant group dominated by Prymnesiophyceae.