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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
(similar to 82% of the total assigned reads), changed to become
dominated by Phycodnaviridae (similar to 90%), while viral activity was
predominantly driven by dsDNA members of the Phycodnaviridae (similar to
50%) and diatom infecting ssRNA viruses (similar to 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.