Genomic analysis of microbial community structures in the Ross Sea during austral summer

The Ross Sea is an ideal area to understand the various ecological responses induced by polynya formation. As the polynya expands during the austral summer and the primary production increases as the base of the food chain in the Ross Sea. We here investigated the microbial communities in the Ross Sea during the austral summer by the genomic analysis. Water samples were collected twice (February 2018 and January 2019) from 8-12 sites near Cape Hallett region. Samples were also obtained from the different depths according to the light penetration value (100%, 50%, 30%, 12%, 5%, and 1%). Quantitative and qualitative analyses were conducted based on the combination of qPCR and next-generation sequencing (NGS) sequencing with three universal primer sets (ribosomal 16S for total microbial community, plastid 23S (p23S) for phytoplankton community, and ribosomal 18S for eukaryotic community, respectively). As a result of metagenomic analysis of the Ross Sea for 2 years, total 8 phyla by 16S primers, 8 by plastid 23S primers, and 14 by ribosomal 18S primers were identified, respectively. The community structures near the coastal water were distinct from those to the offshore similarities indicating the microbial community representing the different environmental conditions to the expanded polynya in the Ross Sea and. This result would provide useful information to understand the changes of energy flow in the Ross Sea according to the changes of polynya formation.