Interaction of Marine Nucleocytoplasmic Large DNA Viruses with Eukaryotic Plankton Communities in the Sub-Arctic Kongsfjorden: A Metagenomic Analysis of Marine Microbial Ecosystems

Abstract

Nucleocytoplasmic large DNA viruses (NCLDVs) infect various marine eukaryotes. Characterizing the ecological relationships between NCLDVs and eukaryotes is critical for understanding marine ecosystems. However, little is known about NCLDV diversity and their relationships with eukaryotic hosts in marine environments. To elucidate the interplay between NCLDVs and the eukaryotic plankton community (EPC) in the sub-Arctic area, we used metagenomics to investigate NCLDVs and the EPC at the Krossfjorden ecosystem of Svalbard (Norway) in April and June 2018. In April, Gyrodinium sp. (Dinophyceae) was the most prevalent eukaryotic taxon in the EPC. However, in June, the pre-dominant taxon was Aureococcus anophagefferens (Ochrophyta). Mimiviridae and Phycodnaviridae NCLDVs appeared in higher proportions increasing the Ochrophyta, Chlorophyta, and Dinophyceae groups. In addition, the non-metric multidimensional scaling analysis showed no difference in vertical zones, but revealed evident differences between April and June for each NCLDV and EPC compositions. Thus, differences in NCLDVs may be caused by changes in EPC compositions according to environmental changes, such as the water temperature and light intensity increases.