13 Viral control of phytoplankton

Abstract

Viral control of phytoplankton Virus ecology is a young rapidly developing field that is changing our understanding of the functioning of marine ecosystems. Viruses are known to be ubiquitous, numerically dominant members of the aquatic microbial communities, infecting a wide spectrum of hosts, including planktonic microalgae. They are typically host‐specific agents of mortality and thus likely influence the dynamics and succession of phytoplankton. As well, viral infection can have major biogeochemical implications through cell lysis and the resulting transformation of released POM into DOM. Bloom forming algal species with their high cell abundance may allow a rapid propagation of lytic viruses, resulting in a direct and significant controlling impact of viruses on bloom dynamics. Besides the concentration of host and virus, other potential factors influencing the quantitative importance of viral control of phytoplankton are resistance of host strains to virus infection (host range), variations in morphotypes of the phytoplankton species, the type of limiting nutrient, and variables affecting the fate of viruses (UV, grazing, adsorption to aggregates). The current presentation will provide examples of viral infected phytoplankton and will address some of the processes involved in viral mediated mortality of microalgae.