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|Title: ||Growth-controlling mechanisms on heterotrophic bacteria in the South China Sea shelf: Summer and Winter patterns|
|Authors: ||Eleanor Austria|
South China Sea
|Issue Date: ||2018-11-12T06:00:53Z
|Publisher: ||Terrestrial, Atmospheric and Oceanic Sciences|
|Abstract: ||Abstract: Mechanisms in controlling the growth of heterotrophic bacteria have seldom
been explored in the tropical South China Sea (SCS). This study reports the tempospatial
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 midshelf,
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.
|Relation: ||29(4) pp.441-453|
|Appears in Collections:||[海洋環境與生態研究所] 期刊論文|
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