Size-dependent spatio-temporal dynamics of eukaryotic plankton community near nuclear power plant in Beibu Gulf, China

Pico- and nano-eukaryotic plankton are important members of marine ecosystems. To understand their community structure and spatio-temporal variations in the Beibu Gulf, and to study the impact of Changjiang Nuclear Power Plant (CNPP) located in the northwest coast of the Hainan Island on the eukaryotic plankton, we studied these issues in the coastal water near CNPP bimonthly from February 2018 to January 2019 via 18S Illumina sequencing. The results reveal a higher genetic alpha-diversity and less beta-diversity of the plankton community in small-size (0.45–5 µm and 5–20 µm) fractions than in large-size (20–200 µm and >20 µm) fractions. The small-sized phytoplankton, including Micromonas (Chlorophyta) and Minutocellus (Bacillariophyta), as well as heterotrophic plankton, including Paraphysomonas (Chrysophyceae), Ellobiopsis (Dinoflagellates), and Syndiniales (Dinoflagellates), took up a considerable proportion in eukaryotic plankton community. In addition, it showed a slight temperature increase and no significant difference in eukaryotic plankton community between the outfall of CNPP and other sampling sites, suggesting that the impact of the thermal discharge from the CNPP on local eukaryotic plankton community was limited.