Participation to the Ocean Sciences Meeting 2024

Gérald GREGORI has presented at the OSM 2024 in New Orleans (USA) a work lead in the context of the BioSWOT-Med cruise. His talk in the session “PI51A: Exploring Microbial Responses to Dynamic Environments: Insights into Aquatic Ecosystems and Global Element Cycling II” was about “Coupling between fine-scale structure and biodiversity: why phytoplankton dynamics is contrasted across a frontal system met in conditions of oligotrophy and moderate energy

Despite their small scale (1-100 km) and relatively short lifetimes (days to weeks) the oceanic fine scales crucially influence Ocean physics and ecology. This is due to the strong gradients induced by their energetic dynamic and associated with strong vertical transport connecting the ocean’s upper layer to its interior. The temporal scale associated with this dynamics is the same as that of many important oceanic processes related to biogeochemical cycles and ecology. Over the past few decades numerous numerical studies significantly improved the characterization of this fine-scale and oceanographic campaigns have demonstrated that fine-scale features can be targeted. But there is still an important lack of empirical evidence for fine-scale processes. The scientific community has been focusing large efforts on novel platforms, among which satellite missions. Remote sensing can provide a synoptic context of fine-scale features, mandatory to disentangle spatial from temporal variability, and supporting adaptive in-situ sampling strategies. The NASA-CNES new satellite SWOT (Surface Water and Ocean Topography) is the most ground-breaking mission for ocean science because of the new altimeter capable to see two-dimensional scenes, like sea surface temperature and ocean color, but without being affected by clouds. The BIOSWOT-Med campaign (2023) focused on an ideal area to verify the hypothesis considering the fine scale circulation as the driver of the plankton biodiversity: The Mediterranean Sea where a high biodiversity is associated with conditions of oligotrophy and moderate energy, unlike oceanic areas as western boundary currents or eastern boundary upwellings that are largely explored but where the intense dynamics or the large nutrient input may mask the fine-scale coupled dynamics. This presentation will introduce the adaptive and lagrangian sampling strategy applied during the cruise and combined with innovative methodologies to obtain a high spatio-temporal resolution and multidisciplinary measurements in the SWOT swaths, with a glimpse on the preliminary results that aim to improve our understanding of the coupling of physical processes to biological ones.