The coastal zone situated at the interface between ocean and continent is a vulnerable region which undergoes a growing anthropogenic pressure due to coastal population growth and changing climate.

In this special issue, we seek to understand and model the impact of the alterations linked to climate change and human activity on the carbon mass balance and the ecosystems in the Rhone River delta and its adjacent coastal Mediterranean Sea. More specifically, we intend to report fluxes of biogeochemical elements from the rivers, in the pelagic and benthic ecosystems collected during the programme CHACCRA and simulate their modification during climate and hydrological alterations. We present papers dealing with the continuous measurements of the river inputs during 2 years underpinning the importance of floods, process studies at sea and in the laboratory on the river plume and benthic biogeochemical fluxes, and a coupled physical-biological process model. Synthesis papers on the fate of Rhone River flood in the Mediterranean Sea and mass balance for carbon in the coastal zone influenced by the river are also presented.