Award: OPP-1642570

One of the key ecosystem services marine communities provide to global health is their consumption of the greenhouse gas methane prior to its release into the atmosphere. While climate models predict that Antarctica has the capability to release the same quantity of methane as all of the Arctic permafrost we lack even a fundamental understanding of those microbial taxa involved in methane cycling in the Southern Ocean, including whether paradigms based on more northerly habitats apply to the Southern Ocean. In 2012, we discovered an expansive microbial mat with methane present at 78 degrees S in the Ross Sea. This habitat formed in 2011. Through analysis of samples collected in 2012 and 2016, here we characterize the underpinnings of this seep, quantify changes in the microbial community, and evaluate the overall functioning of this novel methane seep. We identified that source of the habitat as the degradation of buried organic matter and found that the microbial community was still adapting to the input of methane after 5 years of active methane release. Surprisingly, the taxa observed to consume methane were not those that our current paradigms would suggest should be present in the biogeochemical environment that we measured. In addition, there was still significant methane being released into the water, meaning that the microbial community was not yet at a stage where it could keep up with the rate of methane release. Intellectual Merit: These results help inform our understanding of the overall earth system through identifying that there is a previously unrecognized lag time between the onset of methane emission and the time when methane will be entirely consumed by microbial processes; this finding can be improve the accuracy of future climate models. Further, this research helps explain how microbial ecology and specifically successional patterns may need to be better incorporated into how bacterial and archaeal populations react to environmental change, as community shifts may take years to adapt to new conditions. Finally, we found intriguing similarities among other Antarctic communities that may suggest novel taxa perform a key ecosystem service in Antarctic that are not known from northern regions. As a result, this research has findings that impact global climate models, microbial ecology, as well as the burgeoning field of microbial biogeography. Four scientific publications (three published and one in review) have resulted from this project. Broader impacts: This project has been used to excite, communicate, and educate public and students of all ages about methane and Antarctic Research. The research and results have been presented in pre-K schools, online charter high schools, National Ocean Science Bowl events, numerous undergraduate and graduate courses at Oregon State University (OSU), and scientific outreach events throughout Oregon. These presentations have reached more than 1500 people directly in addition to those reached through social media and web-based outreach. The research has involved two female undergraduate and one female graduate students at OSU. Last Modified: 05/13/2019 Submitted by: Andrew R Thurber