Exploring Nitrogen Cycling in Oxygen-Depleted Oceans: Description From Estuary and Gulf of St. Lawrence

This dataset covers an in-depth study of the nitrogen cycle along the oxygen concentration gradient of the Laurentian Channel in the St. Lawrence Estuary and Gulf. The study, conducted during the summers of 2021 and 2022, aimed to assess the impacts of deoxygenation on the marine ecosystems of this region. To do this, sampling was carried out aboard the Research Vessel Coriolis II. Water samples allowed the measurement of nutrient and dissolved gas concentrations, including N2, Ar and N2O, in the water column. Sediment samples were also collected to perform incubations and characterize pore waters, with the aim of evaluating the contribution of sediments to N2 production and nitrate consumption. The results obtained provide significant insight into the processes of fixed nitrogen loss and changes in stoichiometric ratios induced by deoxygenation in the waters of the St. Lawrence Estuary and Gulf. This study thus allows for a better understanding of the impacts of this phenomenon on the nitrogen cycle and the functioning of these marine ecosystems.