Synechococcus is a widely distributed photosynthetic pico-phytoplankton, which contributes mainly to carbon fixation and maintains the stability of the marine ecosystem. To investigate its distribution patterns in the Yellow Sea, seawater samples were collected during September 2018. Results of flow cytometry analysis showed that the Synechococcus abundance ranged from 6.36 × 102 to 4.51 × 104 cells mL?1, which correlated with salinity (P < 0.01) and temperature (P < 0.05). At deeper off-shore sites, Synecho-coccus showed high abundance at the subsurface thermo-halocline, which was in accordance with chlorophyll a (Chl a) content along the vertical column. Based on the high-throughput sequencing data of rpoC1 (partial gene encoding RNA polymerase), two Synechococcus subclusters, S5.1 and S5.2, were found to coexist in the studied area. Several clades of S5.1, including Clades I,Ⅱ, and Ⅲ, were the dominant components, accounting for 6.63％, 26.11％, and 45.5％ of the total genus, respectively. Redundancy analysis (RDA) showed that nitrite was the main environmental factor that explained the genus composition among samples. Fur-thermore, co-occurrence network revealed that the main phyla that coexisted with Synechococcus were Proteobacteria, Bacteroidetes, Actinobacteria, Planctomycetes, and Verrucomicrobia, which were involved in the carbon (C), nitrogen (N), sulfur (S), and manga-nese (Mn) cycles. Overall, Synechococcus exhibited biogeographic distribution correlated with temperature-salinity and nitrite in the Yellow Sea, and their geochemical function showed diverse but should be further verified in the future.

ZHOU Yuting;WANG Ting;CHEN Xi;QIN Song;ZHAO Zhenjun;GUO Xinyi;LI Jialin

Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences,Yantai 264000,China;College of Life Sciences,Yantai University,Yantai 264000,China;College of Environmental Science and Engineering,Ocean University of China,Qingdao 266100,China;College of Marine Life Science,Ocean University of China,Qingdao 266005,China;Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China

中国海洋大学学报（自然科学英文版）

[1]ZHOU Yuting;WANG Ting;CHEN Xi;QIN Song;ZHAO Zhenjun;GUO Xinyi;LI Jialin-.Distribution Patterns of Synechococcus Indicated Their Environmental Constraints and Related Geochemical Processes in the Yellow Sea)[J].中国海洋大学学报（自然科学英文版）,2022(02):499-508

Indicated,Synecho,subclusters,manga

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