Disentangling the effects of the Agulhas current on marine viruses

Abstract

Traditionally, viruses were considered pathogens of marine organisms. These studies assumed that viruses occurred at low abundances in the oceans and had a limited influence on marine ecosystem function. However, over the past three decades, various studies have confirmed that marine viruses constitute the most abundant entities in the oceans, with current estimates suggesting approximately 1030 viruses globally. In addition to their ubiquitous nature, marine viruses are highly diverse. They infect a wide range of organisms including microorganisms and macrofauna. Consequently, viruses play a significant role in shaping the evolution, community structure and biodiversity of marine populations. Furthermore, there is clear evidence of the profound role played by marine viruses in the cycling of nutrients, organic matter, and energy. Here, we review current insights on the diversity and function of marine viruses. We focus on the impact of environmental variables on viral dynamics, including the viral shunt and the expression of genes that augment host metabolism (Auxiliary Metabolic Genes). We also explore the potential function of viruses in regions that are actively interacting with current climate change, such as the Agulhas Current and the Southern Ocean. Ultimately, this review provides valuable insights into the distribution and ecological contribution of marine viruses.