"PhD Studentship : Microbial ecology of methane cycling in blue carbon ecosystems under changing climate"

University of Birmingham - School of Geography, Earth and Environmental Sciences

Blue carbon ecosystems, such as coastal wetlands, saltmarshes and peatlands, store significant amounts of carbon through sequestration of atmospheric carbon dioxide. In fact, these ecosystems can store up to ten times more carbon per hectare than temperate 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) may outcompete methane-producers for compounds like acetate and hydrogen. However, SRB may not outcompete methanogens for one-carbon compounds. Yet, the impact of rising sea levels, which increase sulfate concentrations, on the activity of methane-producers and SRB, and consequent methane production rates, remains unclear.

Research from our group and others has shown that methane-producers 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 multidisciplinary project will deliver the first comprehensive quantification of one-carbon compound cycling and associated methanogenesis in coastal sediments, and characterize, at unprecedented resolution, the microbial diversity and pathways driving these processes through an innovative combination of cultivation-dependent and -independent approaches.

For further information on this project and details of how to apply to it please visit https://centa.ac.uk/studentship/2026-b11-microbial-ecology-of-methane-cycling-in-blue-carbon-ecosystems-under-changing-climate/

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

Funding notes:

This project is offered through the CENTA3 DLA, funded by the Natural Environment Research Council (NERC). Funding covers: annual stipend, tuition fees (at home-fee level), Research Training Support Grant.

Academic requirements: at least a 2:1 at UK BSc level or a pass at UK MSc level or equivalent.

International students are eligible for studentships to a maximum of 30% of the cohort, provided the University of Birmingham’s international student entry requirements are fulfilled. Funding does not cover any additional costs relating to moving or residing in the UK. Further information: https://www.birmingham.ac.uk/postgraduate/pgt/requirements-pgt/international/index.aspx.

References:

Tsola et al. (2024) ‘Methanolobus use unspecific methyltransferases to produce methane from dimethylsulfide in Baltic Sea sediments’, Microbiome, 12, pp: 3.

Macreadie et al. (2021) ’ Blue carbon as a natural climate solution’, Nature Reviews Earth & Environment 2.

Al-Haj and Fulweiler (2020) ‘A synthesis of methane emissions from shallow vegetated coastal ecosystems’, Global Change Biology, 26.

Jameson et al. (2019) ‘Deltaproteobacteria and Methanococcoides are responsible for choline-dependent methanogenesis in a coastal saltmarsh sediment’, The ISME Journal.