Differences in viral decay and production following exposure to sunlight and dark

Abstract Although we have gained insight into the biological and biochemical effects of natural sunlight exposure on prokaryotes, little is known about sunlight exposure on natural virus communities. To address this question, an investigation of the effects of sunlight and dark treatments on viral communities, viral production and decay rates in Kenting coastal waters was conducted. The average rate of net viral production in the sunlight and dark treatment was 0.010 and 0.018 × 106 viruses mL–1 h− 1, respectively. Furthermore, averaged value for viral decay in the sunlight treatment was 0.016 × 106 viruses mL− 1 h− 1, a significant decrease (ca. 60%=((0.83 − 0.33)/(0.83 × 100%)) was observed in sunlight conditions, whereas no significant changes occurred in dark conditions. The gross viral production under sunlight conditions was slightly higher, however, non-significantly higher than that in the dark treatment. As a result, we suggest that sunlight damages a large portion of the natural viral community, affecting the role viruses play in food webs.