Since 2006, sea-level rise has been steadily increasing, with rates reaching 3.69mm/yr. In this context, coastal ecosystems such as salt marshes are experiencing significant impacts, both in terms of their structural characteristics and their carbon sequestration potential. To investigate their response to sea-level rise, a surface-based approach was applied to monitor a salt marsh in the Isle-Verte region, located in the maritime estuary of the St. Lawrence River, Quebec. This approach made it possible to delineate the different morpho-sedimentary units of the marsh (mudflat, low marsh and high marsh) in order to document their evolution and connectivity. Aerial images covering the period from 1948 to 2022 were mapped, and transition matrices were produced to document areal transfers between the different units. Since 1948, the Isle-Verte salt marsh has experienced a significant increase in its surface area. However, this increase is only observable in the low marsh. In 1948, the marsh area was dominated by a high marsh which was twice as extensive as the low marsh, whereas in 2022 the low marsh occupied the largest area. In addition, recent carbon sequestration rates, representative of the last decades, were calculated and are nearly four times higher in the high marsh than in the low marsh. These results confirm the relevance of applying an area-based approach to temporal reconstructions of salt marshes extent to assess their contribution to carbon sequestration.