Solar radiation shapes viral ecology in an alpine lake at 4700 meters

Solar radiation plays a pivotal role in shaping viral ecology, fundamentally influencing ecological processes and biogeochemical cycles in aquatic environments. However, the dynamics of viruses in high-altitude lakes with intense solar radiation remain largely unexplored, hindering our understanding of their ecological significance. This study investigates diel and vertical variations in viral abundance, activity, diversity, and community in Lake Nam Co at an altitude of 4700 meters. We assess the effects of solar radiation on viral dynamics in the field through parallel light-transmitting and dark incubation experiments. Our findings reveal that intense solar radiation alters viral life cycles by extending latent periods, promoting lysogenic cycles, and accelerating degradation. Diel variations in viral dynamics are shaped by physicochemical shifts, particularly turbidity and pH changes driven by stream inflows, which buffer the effects of solar radiation and obscure clear diel patterns. Conversely, vertical variations in viral dynamics and community composition are predominantly dictated by solar exposure. This research represents the first comprehensive exploration of viral ecology in a high-altitude lake, significantly advancing our understanding of virus-mediated processes in biogeochemical cycling across alpine lake systems globally.