Influence of irradiance and temperature on the virus MpoV-45T infecting the Arctic picophytoplankter micromonas polaris

• Published in: Viruses
• Main Authors: Piedade, G., Wesdorp, E., Montenegro-Borbolla, E., Maat, D., Brussaard, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: Arctic; Global warming; Phytoplankton
• Online Access: https://www.vliz.be/imisdocs/publications/75/322775.pdf

Arctic marine ecosystems are currently undergoing rapid changes in temperature and light availability. Picophytoplankton, such as Micromonas polaris , are predicted to benefit from such changes. However, little is known about how these environmental changes affect the viruses that exert a strong mortality pressure on these small but omnipresent algae. Here we report on one-step infection experiments, combined with measurements of host physiology and viability, with 2 strains of M. polaris and the virus MpoV-45T under 3 light intensities (5, 60 and 160 μmol quanta m −2 s −1 ), 2 light period regimes (16:8 and 24:0 h light:dark cycle) and 2 temperatures (3 and 7 °C). Our results show that low light intensity (16:8 h light:dark) delayed the decline in photosynthetic efficiency and cell lysis, while decreasing burst size by 46%. In contrast, continuous light (24:0 h light:dark) shortened the latent period by 5 h for all light intensities, and even increased the maximum virus production rate and burst size under low light (by 157 and 69%, respectively). Higher temperature (7 °C vs 3 °C) led to earlier cell lysis and increased burst size (by 19%), except for the low light conditions. These findings demonstrate the ecological importance of light in combination with temperature as a controlling factor for Arctic phytoplankton host and virus dynamics seasonally, even more so in the light of global warming.