Seagrass ecosystems are considered key blue carbon sinks due to their capacity to store particulate organic carbon in the sediments. However, other mechanisms of carbon sequestration remain understudied, such as outwelling or export of recalcitrant dissolved carbon. This project aims to unravel these pathways through the study of how theseecosystems influence the seawater carbonate system in present and future climatic conditions. Using advanced instrumentation at Kristineberg Centre—Picarro gas analysers, automatic alkalinity titrators, spectrophotometers, and nutrient analysis facilities— together with in situ field measurements in nearby meadows; the study will assess fluxes of multiple carbon species and greenhouse gases (CO₂, CH₄, N₂O). Results will determine whether these ecosystems act as carbon sinks or sources. Expected outcomes include improved understanding of the role of seagrasses in coastal carbon budgets and guidance for their inclusion in climate mitigation strategies.