AME 65:117-128 (2011)  -  DOI:

Phytoplankton are more tolerant to UV than ­bacteria and viruses in the northern South China Sea

Xiangcheng Yuan1,2, Kedong Yin3,4,*, Paul J. Harrison2, Jiangtao Zhang1

1State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China
2Division of Environment, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR
3School of Marine Sciences, Zhong Shan (Sun Yat-Sen) University, Guangzhou 510275, PR China
4Environmental Futures Centre, Griffith University (Nathan Campus), Brisbane, Queensland 4111, Australia

ABSTRACT: In late summer of 2005, the effects of ultraviolet radiation (UVR) on primary production (PP), bacterial production (BP) and viral decay rates (VDR) were investigated along a salinity gradient in the northern South China Sea. The freshwater input increased the UVA diffuse attenuation coefficient (up to 2.7 m−1) near the Pearl River estuary and consequently influenced the UVR inhibitory effects, as VDR was significantly correlated with the UVA diffuse attenuation coefficient. UVR inhibition of PP was significantly higher in upwelled waters than downwelled waters, suggesting that the vertical mixing (i.e. upwelling and downwelling) was an important factor regulating microbial sensitivity to UVR. UVR inhibited PP and BP by ~15 and 25%, respectively, and the UVR inhibition of BP was significantly higher than that of PP in most of the samples; hence there was a competitive advantage for phytoplankton over bacteria under the relatively high UVR exposure. UVR increased VDR by ~30%, which decreased bacterial mortality by 0.12 to 0.3% h−1 and mitigate the inhibitory effects of UVR on bacteria. In general, phytoplankton were more ­tolerant than bacteria and viruses to UVR in the sub-tropical northern South China Sea.

KEY WORDS: Bacterial production · Primary production · Viral decay · Ultraviolet radiation · South China Sea

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Cite this article as: Yuan X, Yin K, Harrison PJ, Zhang J (2011) Phytoplankton are more tolerant to UV than ­bacteria and viruses in the northern South China Sea. Aquat Microb Ecol 65:117-128.

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