Water masses drive the spatial and temporal distribution of marine Archaea in the northern Antarctic Peninsula.

The Southern Ocean influences the planet's biogeochemical cycles. Marine microorganisms are important in this scenario, being the main biological agents in the cycling of many elements. The Archaea domain is widely distributed in the oceans, and its presence in Antarctica is acknowledged. In this context, this work aimed to analyze the diversity and distribution of archaea according to environmental parameters in the waters surrounding the north of the Antarctic Peninsula. For environmental characterization studies, surface and bottom data were used for the ten monitoring stations of expeditions that took place in the summer of 2014 and 2015. The sequencing of the 16S rRNA gene was performed on the Illumina HiSeq platform, using the SILVA v138 database. The results revealed the presence of three main water bodies: Antarctic Surface Water, Shelf Waters, and modified Circumpolar Deep Water. Deep waters had higher diversity than surface waters, and the dominant groups were Nitrososphaeria and MGII. In the study region, the main factor responsible for the differences in the ecosystems was the presence of distinct water masses and the stratification of the water column. We argue that it is essential to consider water mass dynamics to study the microbial landscape of the Southern Ocean.