The current climate crisis underscores the growing need to develop nature-based solutions to mitigate greenhouse gas emissions. Among these solutions, the conservation of coastal wetlands, and particularly salt marshes, because they play a crucial role as natural sinks for carbon dioxide (CO₂) and contribute substantially to fight climate change. However, blue carbon ecosystems remain poorly documented in northern regions, especially in eastern Canada, where extensive salt marsh areas are present. This study aims to quantify the net carbon budget in the Barachois de Malbaie salt marsh (Gaspésie) using measurements of plot-scale greenhouse gas fluxes, associated environmental variables and soil carbon stocks. The budget combines field measurements of CO₂ and CH₄ fluxes collected during the 2024 and 2025 growing seasons with a quantification of the carbon stored within the main vegetation zones. By integrating these components, the study provides a representative comparison of net surface fluxes and long-term carbon storage at the scale of the entire marsh. Preliminary results show that the Carex paleacea-dominated zone exhibits lower gross ecosystem productivity than the Sporobolus alterniflorus, S. pumilus and S. michauxianus -dominated zones, while methane fluxes are slightly higher in the Sporobolus alterniflorus zone. Together, these patterns suggest a strong vegetation control on CO₂ uptake and CH₄ emissions across the marsh. Together, these patterns underscore the complexity of carbon dynamics in northern salt marshes and emphasize the need to fully resolve their role in climate mitigation.