Experimental Warming Effects on Prokaryotic Growth and Viral Production in Coastal Waters of the Northwest Pacific during the Cold Season

Climate warming can directly affect biological processes in marine environments. Here, we investigated if warming (+2 °C) can change dynamics in viral and prokaryotic populations in the cold seasons in natural seawaters. We monitored the changes in viral production and prokaryotic growth rate. The prokaryotic average gross growth rates were 0.08 and 0.34 h−1 in November and 0.06 and 0.41 h−1 in December in the in situ and warming experiments, respectively. We found that warming water temperature resulted in a significant increase in prokaryotic growth rates. In warming experiments, the overall viral production rate was about 0.77–14.4 × 105 viruses mL−1 h−1, and a rough estimate of prokaryotic mortality was about 5.6–6.8 × 104 cells mL−1 h−1. Based on our estimation, burst sizes of about 21 and 14 viruses prokaryotes−1 were measured under the experimental warming period. Moreover, the results found that an increased water temperature in the subtropical western Pacific coastal waters increases prokaryotic growth rates, enhances viral production, and changes the carbon fluxes in the trophic interactions of microbes.