The development of permafrost bacterial communities under submarine conditions.

Abstract

Submarine permafrost is more vulnerable to thawing than permafrost on land. Besides increased heat transfer from the ocean water, the penetration of salt lowers the freezing temperature and accelerates permafrost degradation. This data set provides sediment temperatures and pore water chemistry from two submarine permafrost cores from the Laptev Sea on the East Siberian Arctic Shelf which inundated about 540 and 2500 years ago. These data are published in partnership with a paper by Magritz et al., that traces how bacterial communities develop depending on duration of the marine influence and pore water chemistry. Magritz et al. (2017) show that submarine permafrost is a source of microbial life deep below the seafloor where it forms an unusual, non-steady state habitat. Pore water chemistry revealed different pore water units that reflected stages of permafrost thaw. Millennia after inundation by sea water, bacteria stratify into communities in permafrost, marine-affected permafrost, and seabed sediments. In contrast to pore water chemistry, the development of bacterial community structure, diversity and abundance in submarine permafrost appear site-specific, suggesting that both sedimentation and permafrost thaw histories strongly affect bacteria. Finally, highest total cell counts, DNA concentrations and bacterial gene copy numbers were observed in the ice-bonded unaffected permafrost unit of the longer inundated core, suggesting that permafrost bacterial communities exposed to submarine conditions proliferate millennia after warming.