EAPSI: Microbial Controls on Arctic Lake Sediment Methane Cycling

Marcus Tamara S, Cedar Rapids IA

Investigators

Abstract

Large amounts of organic matter are stored in permafrost, or permanently frozen northern regions. This organic matter warms and becomes available for microbial communities to turn carbon (C) into the greenhouse gases methane and carbon dioxide via metabolic processes. Microbial communities play a large role in the ultimate fate of this C but have been relatively unstudied in lake sediments in these regions. Therefore, little is known about the dominant lineages present and which microbes are responsible for fueling carbon cycling in these systems. Working with leading scientists in the field of ecosystem genomics at the Australian Center for Ecogenomics, microbial communities present in these systems will be identified, allowing us to determine relationships between species and metabolism of C and contribute to our understanding of ecosystems here in the United States. Due to a lack of empirical data recording interactions between microbial communities and their impacts on the metabolism of carbon (C), accurate modeling of carbon dynamics and the ultimate fate of C has been difficult. Old carbon (C) decomposes to carbon dioxide (CO2) and methane (CH4) from thawing permafrost, which can flow into lakes and drive additional CH4 emission. Our study will address the questions: how do microbial communities interact and affect carbon cycling, which microbial lineages are dominant in lake sediments from within a thawing arctic permafrost system, and contribute to understanding of the broader question: how will climate change effect these microbial communities? DNA extractions will be taken from sediment core samples collected from Stordalen mire peatland complex in northern Sweden. The cores were previously analyzed for geochemical parameters and will be sequenced using the 16S rRNA amplicon sequencing method. Relationships between sequence data and geochemical measurements will be identified at both a species specific and community level, allowing us to characterize dominant lineages and record shifts in microbial communities as a function of thaw. This award, under the East Asia and Pacific Summer Institute program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.