Marine Viruses and Their Impact on Ocean Bacterial Biomass

About 90% of the living biomass in oceans are comprised of microorganisms. Marine viruses are the most abundant living forms in the oceans and numerous viral infections occur every second, influencing the microbial diversity and mortality. Each viral infections is responsible for species distribution, genetic exchange, and evolutionary changes and thus they are reservoirs of genetic diversity. Marine virus research was improved upon the discovery that they are the most abundant living entities in the marine ecosystem. Viruses are also known for their impact on the oceans as well. The genetic diversity of viruses is dependent on the interaction between the viruses and the host organisms and this can further have an impact on the composition of marine microbial communities. Hence marine viruses are considered to play a major role in framing microbial communities and also have an effect on the various biological processes and biogeochemical cycles. Marine viruses have direct and indirect consequences on the biogeochemical cycles, exchange of gases between the atmosphere and the surface water, and the biological carbon pump. Viral shunt is the release of nutrients upon virus-induced cell lysis, thus making it available for the heterotrophs. It is responsible for the release of carbon on a global scale and also alters the nutrient cycling to influence the biological pump. Marine viruses are also affected by the changes in the global climate. This chapter focuses on the abundance, diversity, pathogenicity, and distribution of marine viruses, viral-host interactions, effects of viral infections on the evolution and mortality of aquatic microbial communities, biogeochemical cycles, nutrient cycling, biological pump, and ecological processes and changing global climate.