Effects of temperature and photosynthetically active radiation on virioplankton decay in the western Pacific Ocean

Abstract

In this study, we investigated virioplankton decay rates and their responses to changes in temperature and photosynthetically active radiation (PAR) in the western Pacific Ocean. The mean decay rates for total, high-fluorescence, and low-fluorescence viruses were 1.64 ± 0.21, 2.46 ± 0.43, and 1.57 ± 0.26% h^-1, respectively. Higher temperatures and PAR increased viral decay rates, and the increases in the decay rates of low-fluorescence viruses were greater than those of high-fluorescence viruses. Our results revealed that low-fluorescence viruses are more sensitive to warming and increasing PAR than are high-fluorescence viruses, which may be related to differences in their biological characteristics, such as the density of packaged nucleic acid materials. Our study provided experimental evidence for the responses of natural viral communities to changes in global environmental factors (e.g., temperature and solar radiation).

Figure 1

Sampling area and station locations during the National Natural Science Foundation of China cruise in the western Pacific Ocean from 25 October to 10 December 2012. The in situ environmental parameters and picoplankton abundances were investigated at the 16 stations (black and red dots). The viral decay experiments were explored at six stations (red dots). Cruise track was prepared using Ocean Data View software (version 4.4.1; https://odv.awi.de/).

Figure 2

The total, high-, and low-fluorescence viruses are affected by warming (in situ temperature, 2 °C and 4 °C increases) in six viral decay experiment stations. Error bars indicate the standard errors calculated from triplicate sample measurements.

Figure 3

ANCOVA analysis of significant difference among average total, high-, and low-fluorescence viruses affected by warming (in situ temperature, 2 °C and 4 °C increases). Error bars indicate the standard errors calculated from the six experimental stations. ns, no significant difference; *P < 0.05; **P < 0.01.

Figure 4

The total, high-, and low-fluorescence virus decay rates are affected by different PAR levels (dark, 400, 640, and 880 µmol m⁻² s^–1). Error bars indicate the standard errors calculated from triplicate sample measurements.

Figure 5

ANCOVA analysis of significant differences among average total, high-, and low-fluorescence virus decay rates affected by different PAR levels (dark, 400, 640, and 880 µmol m⁻² s⁻¹). Error bars indicate the standard errors calculated from the six experimental stations. ns, no significant difference; *P < 0.05; **P < 0.01.