EAR-PF: Methane Dynamics in Tidal Salt Marshes: Production and Fate

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Dr. Margaret Capooci has been awarded an NSF EAR Postdoctoral Fellowship to pursue research and further her education at the University of Georgia under the mentorship of Dr. Amanda Spivak. Dr. Capooci will conduct field experiments to better understand methane dynamics in salt marsh soils. Tidal salt marshes, along with mangrove forests and seagrass beds, store large amounts of carbon within their soils. Marshes can also release carbon through several pathways, including methane emission from the soil to the atmosphere. Since salt marshes play an important role in reducing climate change via carbon storage, it is important to understand how, when, and why salt marshes release methane, a gas that contributes to climate change. Therefore, Dr. Capooci’s research aims to better understand the ways in which methane is produced, consumed, and released from salt marsh soils. These data will help scientists better model salt marsh carbon cycling, as well as provide information to better restore and manage salt marshes for their carbon storage benefits. Dr. Capooci will also involve teachers and undergraduate students from underserved and underrepresented communities in her research, including opportunities for hands-on data collection in the marsh.Methane emissions were thought to be low-to-non-existent in tidal salt marshes due to acetoclastic and hydrogenotrophic methanogenesis being outcompeted by sulfur reducers in the soil. However, researchers have found high methane emissions in marshes, as well as an alternative methanogenesis pathway, methanotrophic methanogensis, that uses non-competitive substrates to produce methane. However, methane emissions are highly variable and difficult to predict in salt marshes. Therefore, resolving the heterogeneity regarding CH4 emissions necessitates a closer look at how methane is produced, consumed, and transported under a variety of scenarios, as well as linking these processes to active microbial communities. A combination of techniques will be used in this project, including mesocosm studies, isotopic tracers, qualitative staple isotope probing, and field surveys to assess how methane dynamics change over temporal (i.e., tidal, seasonal) and spatial (i.e., micrometer to plot scale, depth from soil surface) scales. This project aims to advance scientific knowledge of salt marsh carbon cycling by providing mechanistic information regarding methane dynamics that can be applied across sites and be used to up-scale methane fluxes in model runs, as well as provide data to support natural resource managers in the conservation and restoration of salt marshes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.