Consequences of TROPhic REWILDing on AQUAtic ecosystem microbiome and carbon cycling – TropRewild-Aqua

By their activity (e.g., herbivory), large herbivores exert a control on lower trophic levels, from plants to microorganisms, and thus have a major influence on several ecosystem processes, including carbon cycling, a key element of climate regulation. In several degraded ecosystems, the reintroduction of large herbivores (also called “trophic rewilding”) is now envisaged to restore key functions, such as carbon storage/sequestration processes. To date, the influence of large herbivores on microbial communities and biogeochemical cycling has been mostly characterized in terrestrial environments; ignoring consequences on adjacent aquatic ecosystems that play an important role in global carbon cycling. Yet, in tropical Africa -where most ongoing rewilding are occurring- herbivores massively contribute to carbon and nutrient inputs into aquatic ecosystems, therefore modulating microbial activity and processes it supports. TropRewil-Aqua ambitions to understand the consequences of trophic cascades initiated by the reintroduction of African large herbivores on microbial diversity and carbon cycling in aquatic systems. Through the combination of field observations, in- and ex-situ experiments on temporary water bodies and environmental genomic tools, this project aims at i) characterizing the seasonal dynamics of microbial communities and carbon in studied systems, ii) determining the impacts of large herbivores on microbial biodiversity and carbon fluxes, and iii) disentangling mechanisms underlying these impacts. This project will allow to better characterize the functional consequences of trophic rewilding at the landscape-scale, necessary to guide rewilding actions ambitioning to combine biodiversity conservation and climate change mitigation.