Research project This project investigates the consequences of declining oxygen levels in coastal seas and estuaries on microbial processes occurring under anaerobic conditions.
Under-pressure coastal ecosystems are a major problem for human societies because of their essential roles as source of food, resources and their contribution to regulation of Earth´s climate. This project will provide new findings to describe how the expansion of oxygen deficiency impact microbial communities and, thereby, potentially increased emissions of greenhouse gases (N2O and CH4), changes of their contribution to global biogeochemical cycles and microbial-mediated pollutant transformation in coastal systems.
The combination of molecular information from past and modern environments is expected to provide new knowledge to fully comprehend how coastal systems will change in a near future impacted by global warming and local human activities. The recent advances in methods of molecular ecology and bioinformatics allows an in-depth exploration of the taxonomic diversity and metabolic capacities of microbial communities inhabiting aquatic environments at the genome level. Further, the incorporation of environmental paleogenomics data into models as proxy of global biogeochemical cycles is expected to provide a novel view on how microbial metabolisms will be affected by near-future environmental changes related to global warming.
Projections of how the ongoing global climate change will affect the global ocean and thus ecosystem services it provides to human societies is of primary importance as it could help governments to take adequate decisions as well as urge societies to find solutions to prevent the upcoming dramatic damages.
Oxygen deficiency (anoxia) is spreading in coastal seas and estuaries because of anthropogenic loading of nutrients and global warming (Fig. 1A). This has strong implications for ecosystems functioning including the expansion of “dead zones” and severe alterations of global biogeochemical cycles. In anoxic environments, microbial respiration of oxygen is replaced by anaerobic respirations with nitrogen, sulfur, carbon and trace elements as source of energy. In sunlit anoxic environments, certain microorganisms are able to use light to produce matter by a process called anoxygenic anaerobic photosynthesis. Similarly, the microbial transformation of mercury (Hg) into the neurotoxin methylmercury (MeHg), Hg methylation, is predominant in anoxic environments. Yet, there is a lack of knowledge about how (past and ongoing) deoxygenation events modify microbial communities and their contributions to these anaerobic processes, and thus ecosystem functions, and more globally to biogeochemical cycles
The overarching objective of this project is to enhance our understanding of the repercussions of deoxygenation in coastal systems on microbial community diversity and composition, as well as the resulting impacts on ecosystem functions on a larger scale. I will explore three hypotheses : the expansion of anaerobic processes from sediments (Fig. 1B) to water columns (Fig. 1C) contribute significantly to biogeochemical cycles via increased contribution of anaerobic respirations (Hyp1). Additionally, novel niches for microbial anaerobic photosynthesis (Hyp2), and enhanced Hg methylation (Hyp3) are expected to be favored in deoxygenated coastal systems with potential consequences on global biogeochemical cycles, food webs and human health. Existing molecular datasets from Baltic Sea and Black Sea and new dataset from Baltic Sea and Norwegian Fjords will be exploit in this project.
