Eukaryotic nano-phytoplankton plays an indispensable role in energy flow, material circulation, and stability maintenance of marine ecosystems. In this research, DNA metabarcoding technology was applied to elucidate the distribution features of eukaryotic nano-phytoplankton in the Yellow Sea for the first time. The community structure and diversity of eukaryotic nano-phytoplankton were compared based mainly on amplicons of internal transcribed spacer (ITS), 18S rDNA V4 and 18S rDNA V9. Analysis of the correlation between diversity and temperature/salinity was performed as well. The following results were noted. ① Higher proportions of Chlorophyta were obtained based on the ITS region compared with other two amplicons, while the relative abundance of Dinoflagellata was larger when 18S rDNA V4 and 18S rDNA V9 regions were applied.②The abundance-based coverage estimators (ACE), Chao1, Shannon diversity, and Simpson diversity indices were significantly higher based on the amplicon of 18S rDNA V9 than those based on ITS and 18S rDNA V4. The numbers of phyla, classes, order, and families were larger when the 18S rDNA V9 region was applied.③ Based on the amplicons of ITS, 18S rDNA V4, and 18S rDNA V9, the Shannon diversity index showed a significant positive correlation with temperature (P<0.01), indicating that as the temperature increased, the diversity of the eukaryotic nano-phytoplankton increased. The tendency was opposite for salinity, however. With an increase in salinity, the Shannon diversity index decreased significantly (P<0.05). This research compared the community structure and diversity of eukaryotic nano-phytoplankton under different amplicons and will provide a scientific basis for ecological studies of eukaryotic nano-phytoplankton, monitoring of biodiversity and dynamic changes of biological resources, and sustainable development.
Keywords: 18S rDNA V4; 18S rDNA V9; DNA metabarcoding; ITS; biodiversity; eukaryotic nano-phytoplankton.