Description of the thesis topic

Microbial Processes Involved in Carbon Sequestration in Mangrove Ecosystems
This second doctoral thesis will complement another. The student will investigate the (micro-)biological factors in the formation of soil organic matter in different mangrove ecosystems. They will work on selected samples to further study the composition and activity of microbial communities present in different parts of contrasting mangrove ecosystems and their involvement in the formation of stabilized organic matter forms. We hypothesize that the formation of soil organic matter in mangrove systems may be controlled by different mechanisms than in terrestrial systems. Therefore, we will analyze the molecular composition of soil organic matter associated with minerals to determine its origin. We hypothesize that it could be a mixture of plant, algae, and microbial-derived materials. The student will exploit the samples resulting from physical fractionation to study (a) the molecular composition of organic compounds, as well as (2) the quantity, composition and activity of microbial communities in different mangrove soils. He/she focuses on samples with contrasting degrees of stabilization and mechanisms identified in collaboration with another doctoral student (associate).

Work Context

The doctoral thesis will be part of an international project between the University of São Paulo (USP) and the CNRS, comprising two doctoral projects. These two theses will produce highly complementary results, and the two doctoral students will work closely together. For example, they will be involved in sampling, sample preparation, and fractionation procedures. They will share basic data on the physicochemical parameters of soils and their pedogenic environment. This will allow them to co-author articles from both doctoral projects. Regular meetings with the thesis supervisors and joint thesis committees will enrich the overall understanding of the system acquired by the two doctoral students. This project will thus allow for further research, something that cannot be achieved solely on a national scale. USP will benefit from the CNRS's expertise on the processes involved in soil organic carbon sequestration and soil microbial functioning, while the CNRS will benefit from its expertise on carbon storage in mangrove systems. The doctoral student recruited by the CNRS will carry out their field and laboratory work in Brazil.

Constraints and risks

Risks due to tropical context