Algal blooms that form because of phytoplankton proliferation have key roles in marine ecology and carbon fixation. When the blooms die, most of the fixed carbon is transferred to higher trophic levels, and a small fraction sinks into the deep sea. Viral infection is one of the causes of bloom termination, but its effect on the fate and flow of carbon in the ocean is unknown. In this study, Vincent et al. perform a mesocosm experiment to analyse the bloom dynamics of the coccolithophore microalga Emiliania huxleyi and the impact of viral infection on surrounding bacterial communities and the carbon cycle. The authors observed that viral infection was not only the main cause of phytoplankton mortality, but it also shaped the composition of free-living bacterial and eukaryotic species in the blooms. On viral infection of E. huxleyi, the authors found a comparable biomass of eukaryotic and bacterial heterotrophic recyclers, as well as increased organic and inorganic carbon release that contributed to carbon sinking into the deep ocean. Altogether, these results highlight the impact of viruses on the microbial communities of blooms and the consequences on carbon cycling.
Source: Ecology - nature.com
