evidence: This Maroni 2021 mission echoes a pilot mission carried out in 2017, which only targeted fish and vertebrates. It will therefore be possible, thanks to this new expedition, to monitor the evolution of the Maroni River over a 4-year period using standardised methods. These first two sampling campaigns initiate a long-term monitoring process with a view to the eventual deployment of a permanent scientific observatory on this exceptional territory, which is still one of the most preserved areas in Amazonia. This observatory project will be developed in consultation with the actors of research, conservation, and institutions in charge of local and national public policies for the knowledge and preservation of biodiversity in French Guiana.