Impact of floods and primary production on benthic DO, DIC, and AT fluxes in river deltas: a year-round high-frequency timeseries in the Rhône River prodelta

River-dominated ocean margins (RiOMars), located at the land-ocean boundary, are susceptible to both land- and ocean-based stressors. Due to climate change, hydrological regimes are expected to change, with, for example, an increase in the intensity and frequency of river floods in the near future. To better understand the impact of these changes on the benthic ecosystem in RiOMars, we conducted eleven sampling campaigns in the Rhône River prodelta (Mediterranean Sea, France) between October 2023 and September 2024. We measured variations in benthic fluxes of dissolved oxygen (DO), dissolved inorganic carbon (DIC), and total alkalinity (AT), using ex-situ core incubations. Our results show that the integrated benthic fluxes were -26 ± 4, 54 ± 6, and 41 ± 5 mmol m-2 d-1 for DO, DIC, and AT, respectively, with strong variability throughout the year. The lowest fluxes (DIC: 27 ± 7, AT: 21 ± 6, DO: -20 ± 4 mmol m-2 d-1) were observed after large flood depositions, while higher fluxes occurred after smaller flood depositions. The highest rates (DIC: 104 ± 8, AT: 81 ± 6, DO: -35 ± 9 mmol m-2 d-1) occurred in spring and early summer.