Austria, Eleanor S.Eleanor S.AustriaLai, Chao-ChenChao-ChenLaiCHIA-YING KOLee, Kuo-YuanKuo-YuanLeeKuo, Hsiang-YiHsiang-YiKuoChen, Tzong-YuehTzong-YuehChenTai, Jen-HuaJen-HuaTaiShiah, Fuh-KwoFuh-KwoShiah2020-02-062020-02-06201810170839https://scholars.lib.ntu.edu.tw/handle/123456789/454380https://www2.scopus.com/inward/record.uri?eid=2-s2.0-85054932717&doi=10.3319%2fTAO.2018.01.19.01&partnerID=40&md5=f912b982c57a37da90d46d013564bd05Mechanisms in controlling the growth of heterotrophic bacteria have seldom been explored in the tropical South China Sea (SCS). This study reports the tempo-spatial distribution patterns and the controlling mechanisms of bacterial biomass (BB), production (BP), and specific growth rate (Bμ) from one summer (Jun 2010; 4 transects) and two winter (January and December 2011; one transect each) cruises along the northern SCS-shelf. In summer, all three bacterial variables showed strong gradients with greater readings at the inner-shelf then decreasing seaward. The positive correlations of bacterial production rate (BP) and bacterial specific growth rate (Bμ), with primary production (PP), chlorophyll-a, and dissolved organic carbon observed in summer indicate a high possibility of bottom-up (substrate supply) control. Positive bacterial temperature response was observed in the inner to mid-shelf area in winter. There, Bμ changed proportionally with temperature up to ca. 22°C. The Q10 (the increase of reaction rate for a temperature rise of 10°C) for Bμ was ~4.0, which was in the range reported by coastal studies. Very high BP/PP ratios (summer average: 89 ± 92%; winter average: 131 ± 88%) indicated bacteria carbon demand relied heavily on allochthonous organic carbon sources such as river input and re-suspension processes, and that the SCS-shelf might be net heterotrophic in these two seasons. In winter, BP/PP ratios changed positively with temperature in areas inside the mid-shelf, suggesting that the coastal zone might become a stronger CO2 source during cold season under a warming climate, if anthropogenic loadings of inorganic nutrients and organic matter remain high in the future. © 2018 Chinese Geoscience Union. All Rights Reserved.Bacteria; Continental shelf; DOC; Microbial loop; Primary production; South China Sea; Tropical shelf-sea[SDGs]SDG13bacterium; biomass; growth rate; growth response; spatial distribution; summer; temporal distribution; winter; Pacific Ocean; South China Sea; Bacteria (microorganisms)journal article10.3319/TAO.2018.01.19.012-s2.0-85054932717