The BioSWOT2025 meeting was an opportunity to present the first confirmed results of the BioSWOT-Med campaign, which took place in 2023 and explored the influence of oceanic eddies, fronts and filaments on marine biodiversity in the north-western Mediterranean Sea.
The launch meeting of the ANR and the BioSWOT post-campaign (BioSWOT2025) was held at the Institut Méditerranéen d'Océanographie (MIO), in Marseille, France, from 5 at 7 May 2025. More than 45 researchers from France, Italy, New Zealand and the United States took part, many of them young researchers.
The aim of BioSWOT2025 was to share the initial results of the analysis of the data and samples collected during the BioSWOT-Med campaign. This campaign explored a specific oceanic regime, the " fine scales "They are thought to play a vital role in marine life, but are largely unknown in many ocean regions such as the Mediterranean.
"This is a historic moment for the exploration of the fine scales of the ocean, with a SWOT resolution 10 times greater than what we had before", commented Francesco d'Ovidio (LOCEAN-IPSL), PI of ANR BioSWOT project and CNES Ocean Lead within the SWOT scientific team. Indeed, for the first time ever, high-definition SSH data derived from SWOT satellite measurements were used to inform the adaptive sampling strategy employed during an oceanographic campaign, which targeted physical and ecological processes, from nutrient concentration to top predator distribution, using a wide range of techniques, from autonomous platforms to genomics. The comparison of SWOT maps and in situ observations also provided an opportunity to reflect on how the sampling strategy used worked to detect small-scale ocean features.
More than 30 lectures were given over the three days of the meeting, and researchers discussed other collaborations or tools (such as a modelling framework) that are now needed to take things further.
Attempting to unravel the processes underlying physical dynamics and biological interactions
One of the main research objectives of the topic of discussion is to understand how different small-scale processes interacted to produce the physical dynamics and biological interactions observed on an anticyclonic front and eddy encountered during the campaign in the northern Balearic Sea. In this respect, Monique Messié (MBARI) illustrated the growth-advection method as a possible Lagrangian modelling approach for studying planktonic diversity.
Louise Rousselet (LOCEAN-IPSL) summarised the information needed to inform a discussion of the biophysical landscapes revealed by the data acquired in BioSWOT-Med, while Magali Lescot (MIO) illustrated the wide range of results obtained from marine genomics. By applying omics techniques (metabarcoding, metagenomics and metatranscriptomics), the aim is to study the impact of fine oceanic scales on planktonic diversity. More specifically, to identify the species present, the biological functions present and those that were active at the time of sampling in the different types of water body sampled during the campaign. The study of omics techniques is the subject of the ANR BioSWOT. How can we make the best use of the omics information received (for which questions)?
Strong participation from students and post-docs
One of the aims of the meeting was also to highlight the contribution of students and young researchers to SWOT-related research. Out of 30 presentations, 10 were given by students and post-doctoral researchers. Ludivine Grand and Lou Byrnesboth Masters students, respectively presented preliminary results on the fine-scale distribution of ultraplankton and a Lagrangian study of fine-scale dynamics.
Among doctoral students, Aude Joel (MIO) presented biogeochemical data on fine-scale ocean circulation and nutriclines, while Laurina Oms (MIO) presented results on contrasting phytoplankton communities along the front using flow cytometry. Camille Cardot presented a case study on mesoscale activity, comparing data derived from ocean currents from commercial vessel positions and SWOT. The presentation by Maxime Arnaud focused on vertical velocities derived from acoustics, while that of Maxime Duranson focused on the distribution of zooplankton on a fine scale.
Three post-doctoral researchers presented their results. Robin Rolland focused on vortex-wind interactions. Théo Garcia presented the statistical approach he used to highlight the adaptation of phytoplankton to oceanic fronts, while Alexandre Barboni compared estimates of geostrophic and ageostrophic velocities derived from SWOT and ADCP measurements and from numerical simulations. The results ofEmily Wagonner and d'Alba Filella focused on the distribution of organophosphate esters and polyphosphates.
Unexpected results and new research questions
Anthony Bosse (MIO) presented a small-scale description of the anticyclone sampled during the BioSWOT-Med campaign, while Stéphanie Barillon (MIO) presented the results obtained with one of the only two systems currently available for in situ measurements of vertical speed. Maristella Berta (ISMAR-CNR) illustrated the agéostrophic dynamics reconstructed from the analysis of drifting buoys, while Riccardo Martellucci (OGS) presented the preliminary results of biophysical analyses of Argo floats. The presentation by Jean-Baptiste Roustan focused on the preliminary results of the two-ship strategy during the WEMSWOT/CSWOT carried out just before BioSWOT-Med.
Claude Estournel (LEGOS) and Valérie Garnier (IFREMER) compared the results of the Symphonie and Croco models with SWOT data, while Mathilde Cancet showed how SWOT data can help to understand the mechanisms of North Current intrusions on the shelf.
Sandra Nunige (MIO) gave a brief update on the extensive nutrient dataset it has helped to create, with analyses carried out on board during the cruise (inorganic nutrients) and in the laboratory. Dominique Lefevre (MIO) presented preliminary results on the surface mapping of net community production, while the presentation by Marc Tedetti (MIO) focused on the distribution of CDOMs and FDOMs during the BioSWOT-Med campaign. Daniela Banaru (MIO) talked about phytoplankton and zooplankton biomass, biochemical content and stable isotope ratios by size fraction.
Among the preliminary results presented at the meeting, some unexpected ones raised new research questions. For example, analyses ofAlice della Penna (University of Auckland) from an experiment she conducted in mesocosms aboard L'Atalante, to estimate the impact of daily vertical migration of mesozooplankton in surface phytoplankton communities, have suggested several competing hypotheses. The question also remains open as to how the patterns observed might evolve in different water masses and the role of irregular distribution in the ocean. For its part, Elvira Pulido (MIO) has also shown unexpected results on phosphorus availability and the uptake of dissolved organic matter by phytoplankton. The study of these new and competing hypotheses will require the collaboration of the interdisciplinary BioSWOT-Med team.
Karine Leblanc (MIO) showed breathtaking images of nano and microplankton (electron microscopy) and described their distribution during the BioSWOT-Med campaign.
Contrasting ocean conditions, perhaps representative of other parts of the Mediterranean?
The researchers were also interested in discussing how the physical mechanisms and biological response encountered during the cruise are specific to the Mediterranean Sea and which may be typical of generically oligotrophic and moderately energetic conditions.
In this respect, the meeting closed with a conference by Mark Ohman (SCRIPPS), which presented data collected south of Menorca and inside the anticyclonic eddy identified using SWOT images in the north-east of the Balearic Islands by the Zooglider, a unique autonomous robotic instrument that dives to a depth of 400 metres and profiles plankton using an imaging camera and active sonar as it rises in the water column. The two regions differed in terms of temperature, salinity, chlorophyll concentration and optical transparency. At the same time, the plankton communities also differed.
Publications and next steps
The meeting began on the first day with the distribution to all participants of the book " People, science and instruments of the BioSWOT-Med campaign "It was created to give an insight into the scientific richness of an oceanographic campaign and to preserve the memory of the passion and dedication of the participants in the BioSWOT-Med project. It concluded on the third day with a general discussion on the scientific challenges ahead and the strategy to be adopted to tell the story of BioSWOT-Med. "the story of a front, a high and a stormthe oceanographic characteristics and meteorological conditions encountered during the BioSWOT-Med campaign.