Diving into the Deep: Unraveling the Significance of Viruses in the Ocean

Viruses are considered the most abundant biological entities on our planet, exceeding the abundance of their hosts by at least an order of magnitude. In aquatic ecosystems, viral infections kill 10–20% of all microorganisms every day. They thus play a crucial role, specifically in the control of microbial populations and nutrient recycling. In addition, viruses contribute to the evolution of their microbial hosts as vectors of horizontal gene transfer. The magnitude of viral infections and the role they play in deep-sea sediments remain unconstrained. In this seminar, I will present results from two different projects aiming at further our understanding of viral infections in deep-sea sediments.

First, we estimated viral production and prophage induction in sediments from the South Atlantic Gyre collected during IODP Expedition 393 South Atlantic Transect II to calculate viral production to estimate carbon turnover from viral infections. Second, using a host-centric approach, we aimed to characterize viruses associated with the Foraminifer holobiome. Foraminifers are small animals used by micropaleontologists to recreate the history of the planet's climates; therefore, this work has the potential to elucidate the role of viruses in past diversity turnovers and mass mortality events of foraminifera and other eukaryotes.