Elucidating Viral Communities During a Phytoplankton Bloom on the West Antarctic Peninsula

Abstract

In Antarctic coastal waters where nutrient limitations are low, viruses are expected to play a major role in the regulation of bloom events. Despite this, research in viral identification and dynamics is scarce, with limited information available for the Southern Ocean (SO). This study presents an integrative-omics approach, comparing variation in the viral and microbial active communities on two contrasting sample conditions from a diatom-dominated phytoplankton bloom occurring in Chile Bay in the West Antarctic Peninsula (WAP) in the summer of 2014. The known viral community, initially dominated by Myoviridae family (∼82% of the total assigned reads), changed to become dominated by Phycodnaviridae (∼90%), while viral activity was predominantly driven by dsDNA members of the Phycodnaviridae (∼50%) and diatom infecting ssRNA viruses (∼38%), becoming more significant as chlorophyll a increased. A genomic and phylogenetic characterization allowed the identification of a new viral lineage within the Myoviridae family. This new lineage of viruses infects Pseudoalteromonas and was dominant in the phage community. In addition, a new Phycodnavirus (PaV) was described, which is predicted to infect Phaeocystis antarctica , the main blooming haptophyte in the SO. This work was able to identify the changes in the main viral players during a bloom development and suggests that the changes observed in the virioplankton could be used as a model to understand the development and decay of blooms that occur throughout the WAP.

Virome composition in marine fish revealed by meta-transcriptomics

“…2017 ), latitude ( Gregory et al. 2019 ), and phytoplankton bloom development ( Alarcon-Schumacher et al. 2019 ).…”

Oceanographic Fronts Shape Phaeocystis Assemblages: A High-Resolution 18S rRNA Gene Survey From the Ice-Edge to the Equator of the South Pacific

“…Viral predation also appears to be strain specific, with previously isolated strains found to infect only P. globosa (Schoemann et al, 2005) and P. pouchetti (Bratbak et al, 1998). Interestingly, besides recent reports of a virus predicted to be capable of infecting P. antarctica (Alarcon-Schumacher et al, 2019), no virus confirmed to infect P. antarctica has been isolated thus far. Finally, less species can tolerate the extreme environmental conditions (e.g., low temperatures) or increased variation of climatic conditions at higher latitudes (i.e., climate harshness/stability hypothesis) (Currie et al, 2004).…”

Temporal Variability of Virioplankton during a Gymnodinium catenatum Algal Bloom

“…Gong et al [54] suggested that Cellulophaga phages, Pseudomonas phages, and Vibrio phages were responsible for the high percentage of surface water viromes in Prydz Bay. In Chile Bay, an integrative omics study demonstrated that the phage community associated with bacterioplankton was dominated by a new Pseudoalteromonas virus (PpCBA) during a diatom-dominated phytoplankton bloom [64]. As the main driver, bacteria play multiple ecological roles in phytoplankton blooms, killing hosts, degrading biopolymers, and recycling algae-derived organic matter.…”

“…By contrast, the negative correlations reflect the appearance of kill or lyse algal cells. Lysis activity related to bloom-forming species, such as Emiliania huxleyi, Phaeocystis pouchetii, and Phaeocystis globose, has been well studied [38,64]. During such blooms, viruses exhibit a strong regulation activity and contribute to HAB collapse in a boom-and-bust pattern [68][69][70].…”