The Characteristics and Distribution of Eukaryotic Phytoplankton Community in Liaodong Bay, China

Brown tides have occurred in the Bohai Sea of China since 2009 and caused serious losses in aquaculture. In recent years, phytoplankton identification has been greatly promoted by the development of high-throughput sequencing technologies. In this study, V4 region of 18S rDNA was used as the target gene to design the primer V4 (F/R), and high-throughput sequencing technology was adopted to evaluate the diversity of composition and characteristics of the eukaryotic phytoplankton community. A total of 93 alga species were identified, and about 60% (56 out of 93) of them were undetected or unreported in Chinese waters. There were 59% of the total algal species identified as autotrophy in trophic mode while heterotrophy and mixotrophy accounted for 12% and 29% of the total algal species, respectively. 8 species of picophytoplankton that were mainly distributed in the south and a partial area of the east and west formed the scientific basis for the quality and safety early-warning in aquatic products and brown rides study. Diversity index analysis also revealed a trend of fluctuations of marine phytoplankton diversity in different sample sites in Liaodong Bay. In conclusion, our work provides a detailed evaluation of eukaryotic phytoplankton diversity in Liaodong Bay, suggesting the need for long-term monitoring to further study and guard against the potential risk of harmful algal blooms.