Metavirome Profiling and Dynamics of the DNA Viral Community in Seawater in Chuuk State, Federated States of Micronesia

Abstract

Despite their abundance and ecological importance, little is known about the diversity of marine viruses, in part because most cannot be cultured in the laboratory. Here, we used high-throughput viral metagenomics of uncultivated viruses to investigate the dynamics of DNA viruses in Chuuk State, Federated States of Micronesia tropical seawater sampled in March, June, and December, 2014. Among the identified viruses, 71–79% were bacteriophages belonging to the families Myoviridae, Siphoviridae, and Podoviridae (Caudoviriales), listed in order of abundance at all sampling times. Although the measured environmental factors (temperature, salinity, and pH) remained unchanged in the seawater over time, viral dynamics changed. The proportion of cyanophages (34.7%) was highest in June, whereas the proportion of mimiviruses, phycodnaviruses, and other nucleo-cytoplasmic large DNA viruses (NCLDVs) was higher in March and December. Host species were not analysed, but the dramatic viral community change observed in June was likely due to changes in the abundance of cyanophage-infected cyanobacteria, whereas changes in NCLDVs was likely due to the abundance of potential eukaryote-infected hosts. These results can serve as a basis for comparative analyses of other marine viral communities and guide policy making when considering marine life care in Chuuk State.