Horizontal and vertical distribution of marine virioplankton: a basin scale investigation based on a global cruise.

Despite the fact that marine viruses have been increasingly studied in the last decade, there is little information on viral abundance and distribution on a global scale. In this study, we report on a global-scale survey covering the Pacific, Atlantic, and Indian Oceans on viral distribution using flow cytometry. Viruses were stained with the SYBR Green I, which targets only dsDNA viruses. The average viral abundance was 1.10±0.73×10(7) ml(-1) in global surface oceans and decreased from the areas with high chlorophyll concentration (on average, 1.47±0.78×10(7) ml(-1)) to the oligotrophic subtropical gyres (on average, 6.34±2.18×10(6) ml(-1)). On a large-spatial-scale, viruses displayed significant relationships with both heterotrophic and autotrophic picoplankton abundance, suggesting that viral distribution is dependent on their host cell abundance. Our study provided a basin scale pattern of marine viral distributions and their relationship with major host cells, indicating that viruses play a significant role in the global marine ecosystem.