PhD Studentship: Microbial Ecology of Methane Production in Blue Carbon Ecosystems Under Changing Climate

Blue carbon ecosystems, such as coastal wetlands, saltmarshes and peatlands, store significant amounts of carbon in their vegetation and soils through sequestration of atmospheric carbon dioxide. In fact, these ecosystems can store up to five times more carbon per hectare than tropical forests, underscoring their strong potential for climate change mitigation. However, blue carbon ecosystems are also significant sources of methane, a potent greenhouse gas with ~80 times the global warming potential of carbon dioxide over a 20-year period and rising atmospheric concentrations. Therefore, understanding the extent of methane production from these ecosystems is essential.

In coastal environments, the majority of methane is produced by microbial degradation of one-carbon compounds such as methanol, methylamines (MAs) and dimethylsulfide (DMS). This is because coastal sediments typically have high salinity, and thus high sulfate levels. In high-sulfate ecosystems, sulfate-reducing bacteria (SRB) have a thermodynamic advantage and outcompete methanogens for compounds like acetate and hydrogen. However, SRB may not outcompete methanogens for methanol, MAs and DMS. Yet, the impact of rising sea levels, which increase sulfate concentrations, on the activity of methanogens and SRB, and consequent methane production rates, remains unclear.

Research from our group and others has shown that methanogens from various genera (e.g. Methanomethylovorans, Methanolobus and Methanococcoides) can utilise one-carbon compounds to produce methane in diverse coastal sediments with varying sulfate availability such as saltmarshes and peatlands. Recent DNA-based studies have expanded our understanding of methanogens to novel phyla such as Bathyarchaeota and Methanomethyliaceae. These studies suggest that the degradation of one-carbon compounds plays a critical role in methane production in blue carbon ecosystems and that the diversity of methanogens in these settings is more widespread than previously thought. Still, there is a significant gap in our knowledge of the microbial diversity and metabolic pathways underpinning one-carbon compound degradation in coastal blue carbon sediments under changing climatic conditions (i.e. rising temperature and salinity). This project aims to fill this knowledge gap by studying the microbiology of methane production in blue carbon ecosystems and how environmental factors regulate this process.

For further information on this project and details of how to apply to it please click on the above 'Apply' button

Further information on how to apply for a CENTA studentship can be found on the CENTA website: https://centa.ac.uk/

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