The EU-funded Arctic PASSION project is co-creating an observing system that is better tuned to deliver on the needs of Arctic societies, and that enables a more holistic approach to monitoring of environmental changes to support decision making at local, national and international levels. Arctic Indigenous communities and northern communities are engaged in these activities which involve consideration of high quality, science-based Earth observation information, and of consented Indigenous Knowledge (IK) and Local Knowledge (LK).

We will showcase our activities on 

• the co-creation of an Indigenous-led database that documents local bio-cultural events in several Arctic communities, 
• the co-creative establishment of a monitoring system for noise pollution affecting marine mammals with local hunters in Qaanaaq, Greenland, and 
• the initiation of an expert panel of Indigenous and non-Indigenous Arctic people jointly with researchers, and representatives of government agencies and the private sector, to improve coordination of sea ice and related observations by incorporating   Indigenous and Local Knowledge and filling gaps in current monitoring systems to provide shared benefit to Arctic communities, and across regions and sectors . 

In addition we will present our activities to form an Arctic Ocean Regional Alliance (ArORA)  under the Global Ocean Observing System (GOOS) framework that will enhance collaboration and coordination of actions dedicated to the Arctic Ocean, bringing together coastal communities, scientists and other Arctic actors.

How to cite: Karcher, M., Dawson, J., Murray, M., Mustonen, T., Nikolopoulos, A., Olsen, S. M., Roto, J., Simon Hegelund, M., Sundfjord, A., Wells, T., and Wilkinson, J.: Arctic PASSION – Working together towards a better coordinated, integrated, equitable and useful Arctic Observing System: successes, challenges and lessons learnt, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1227, https://doi.org/10.5194/oos2025-1227, 2025.

The European Marine Observation and Data Network, EMODnet, is a public marine data service of the European Union and a key marine knowledge initiative of the European Commission DG MARE. The guiding philosophy of EMODnet is to make marine data Findable, Accessible, Interoperable and Reusable (FAIR), providing a marine knowledge resource that is open to all. EMODnet today is an operational service with a single Portal (emodnet.ec.europa.eu) providing open and free access to high-value datasets and derived data products on the marine and coastal environment and human activities at sea, at European scale and beyond. To deliver this, EMODnet experts work closely with Europe’s Ocean observation community to assemble in situ marine data from diverse data collection efforts and stakeholder groups, including the public and private sectors. EMODnet standardises and harmonises these data into integrated pan-European data layers and derived data products, utilising marine and geospatial data standards e.g., INSPIRE, controlled vocabularies and standards from EMODnet’s foundational marine data management infrastructures e.g., SeaDataNet, Open Geospatial Consortium (OGC) and restful (OPeNDAP) data services, and ISO metadata standards, to name a few.

Through these activities EMODnet delivers the most comprehensive and diverse in situ marine data service in Europe, offering data and information across seven broad thematics: bathymetry, biology, chemistry, geology, seabed habitats, physics and human activities at sea. The offer extends from the open ocean and deep sea/seafloor to the surface waters and coastal zone, including the land-sea interface, with in situ data offering high resolution and profiles of the ocean that can be used not only for European and regional sea-scale but also for localised applications. As a result, the EMODnet service has a large and expanding user network with trusted marine data being used for research and innovation, to drive further understanding about our shared Ocean, used as evidence to underpin decision-making in ocean management and governance, including Maritime Spatial Planning, and used to support the private sector in its transition to more sustainable, green and climate-smartoperations at sea.

EMODnet is also recognised as a best practice and an innovator in FAIR data and metadata services, not least due to its unified marine data service based on a distributed infrastructure of interoperable web services. This centralised approach is key to the EMODnet offer of FAIR multi- and inter-disciplinary marine knowledge and is underpinning a new wave of innovation in marine data services. At European level, EMODnet closely collaborates with the Copernicus Marine Service, and together they are delivering the marine data infrastructure for the European Digital Twin Ocean (EDITO), as a marine domain contributor to EOSC, the EU Green Deal data space and Destination Earth, among others.  The centralised Portal is also a key milestone in EMODnet’s contribution to global efforts, with EMODnet’s common metadata catalogue being harvested by the Global Earth Observation System of Systems (GEOSS) and the Ocean Data Information System (ODIS) of IODE IOC-UNESCO, as a key contribution to the global ocean data ecosystem.

How to cite: Larkin, K., Delaney, C., Collart, T., Karampourouni, A., Beja, J., Vanhoorne, B., Leclerq, F., Schmitt, T., Souf, A., Giorgetti, A., Kaskela, A., Pititto, A., Karvinen, V., Novellino, A., Gorringe, P., Schaap, D., and Iona, S.: EMODnet: An EU data service providing FAIR, integrated marine data for the global ocean data ecosystem , One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1253, https://doi.org/10.5194/oos2025-1253, 2025.

Coral reefs are highly productive ecosystems where bacterioplankton play a critical role in recycling dissolved compounds, enabling corals to thrive in oligotrophic waters. Reefs worldwide exhibit trends of declining coral cover with concomitant increases in macroalgae. This project seeks to understand how these trends may alter microbial carbon and nutrient recycling supporting the resilience of reefs to climate change. Decadal data from the Moorea Coral Reef Long Term Ecological Research program (MCR LTER) show that reefs have suffered significant structural damages from past cyclonic events, ongoing anthropogenic impacts and predator outbreaks (Taramea or Crown-of-thorn starfish Acanthaster planci), resulting in phase shifts from coral to macroalgal dominance. Previous research suggests that phase shifts reduce microbial diversity, increase heterotrophic bacteria and disrupt bacterioplankton recycling, leading to inefficient productivity and further coral decline. Mesocosm experiments simulated coral-dominated, algae-dominated, and post-disturbance reefs (A. planci outbreak) to assess the effects of benthic cover on compositional dynamics of microbial communities and dissolved organic matter. Organic matter (fDOM and DOC) quantification was done via fluorescence spectroscopy and catalytic oxidation, while microbial community analysis was done using flow cytometry with amplicon next generation DNA sequencing. The results of this project will enhance our understanding of the interactions between bacterioplankton communities and benthic species, with implications for carbon fixation and remineralization processes in the oligotrophic ecosystems of the South Pacific. Additionally, findings from this study will provide a valuable baseline for assessing the ecological status of locally managed lagoons, supporting parallel research efforts in remote regions of Tahiti.

How to cite: Rochette-Yu Tsuen, K., Diaz, L., Silbiger, N., and Nelson, C.: Coral-Algal Phase Shifts Impact Microbially-Mediated Organic Carbon Processing in Coral Reefs of Mo’orea, French Polynesia, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-764, https://doi.org/10.5194/oos2025-764, 2025.

Addressing hydrological, biogeochemical and biological variability in marine systems at different scales is essential for understanding their functioning and fate in the context of global change and increasing anthropogenic pressure. Sub-mesoscale features and processes are particularly relevant in coastal, marginal and shelf seas, and frontal systems (such as Regions Of Freshwater Influence, tidal fronts, upwelling and eddies), being particularly sensitive to extreme events and influencing human health, economy, and well-being. Phytoplankton integrated observation combines reference methods, remote sensing, and innovative automated approaches to decipher intricate dynamics. For more than a decade, in vivo/in situ techniques for monitoring phytoplankton have been deployed in different coastal and offshore systems, on a variety of platforms and frames, from dedicated research cruises, fixed stations and moorings to measurements of opportunity, supported by different collaborative national or international projects. These measurements provide information on the variability of phytoplankton functional groups (automated flow cytometry, multispectral fluorometry) and main taxa (imaging in flow) as well as physiological changes (variable fluorometry) at high spatial and temporal resolution. They help assigning community changes to different environmental conditions, complementing physical, biogeochemical and biological observations. In the present study, we present and discuss some applications of automated in vivo approaches addressing phytoplankton dynamics and functional diversity in a variety of marine systems, at sub mesoscale, spanning from coastal and frontal temperate and tropical systems, to open ocean. We emphasise the need for better interoperability between devices and techniques and better harmonisation in data pipelines conforming to the FAIR principles, as well as for applying automated data classification and synthesis tools based on conventional statistics as well as on Artificial Intelligence/Machine Learning. These approaches allow addressing scientific, societal and economic challenges through a new perspective, facing local and global changes. 

How to cite: Artigas, L. F., Hubert, Z., Aardema, H., Haraguchi, L., Fragoso, G., Creach, V., Thyssen, M., Gregori, G., Casotti, R., Louchart, A., Epinoux, A., Machu, E., Moller, K., Karlson, B., Eikrem, W., Vlasicek, I., Lefebvre, A., Deneudt, K., Claquin, P., and Ternon, J.-F. and the other contributors to the presentation Integrated Observation of Phytoplankton Dynamics: Integrated observation of phytoplankton dynamics at sub-mesoscale in coastal and frontal systems: insights from deploying automated optical approaches, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-847, https://doi.org/10.5194/oos2025-847, 2025.

The Antarctic Treaty and the Convention on the Conservation of Antarctic Marine Living Resources have been enormously successful at maintaining peace in the region which includes the vast and crucial Southern Ocean. Nonetheless, there are several increasing threats to biodiversity in this region, including the rapidly changing climate, fishing, tourism, and now diseases such as avian flu. Some of these have been able to be addressed by the parties, but others have not yet.

There are various means for biodiversity and ecosystem protection available under the two treaties: species-based, area-based, and activity-based tools. There are also helpful principles for protection, such as the need for precaution, for environmental impact assessment and monitoring, and for evidence-based decision-making. However, the adoption of these protective tools has been increasingly hampered by a lack of consensus among all treaty parties. The creation of protected areas and protected species designations have faced the most disagreement. For example, in 2024, proposals were unable to be agreed to for the special protection of Emperor penguins, nor for a marine protected area around the Antarctic Peninsula; moreover, an existing Conservation Measure for the krill fishery in that area was unable to be continued. This was despite science underpinning all parties' discussions.

This paper examines innovative legal tools and approaches to integrated protection for governance of the Southern Ocean. Integration is already being trialed for matters that are typically considered separately, such as krill fishery management, marine protected areas, and environmental impact monitoring. Climate change will need to be integrated with these and other tools, such as via climate-smart marine spatial planning.  However, much more is needed.

Such innovative legal tools and approaches need to emphasise commonalities between states, for better integrated ocean and biodiversity protection. These may or may not include emphasising intrinsic value and/or rights of nature; interpretations of these concepts will need to be chosen that are not culturally specific. This paper suggests that more important will be frameworks and approaches that prioritise responsibility, respect and guardianship in our governance of the Southern Ocean.

This paper examines methods for adopting human and state responsibilities for the protection of Antarctic and Southern Ocean species and ecosystems. Ancient, kinship-based approaches are considered, as are different religious or spiritual approaches. It considers the knowledge and belief systems that underpin such approaches, and how they might be included in science-based decision-making processes such as for Southern Ocean governance.  It considers whether such approaches may better cross cultural boundaries and achieve consensus, particularly when compared with rights-based ones. Only ones that can achieve consensus will ensure the maintenance of Southern Ocean species, ecosystems, and functions. Achieving consensus will enable the Southern Ocean to continue its global role in the maintenance of the health of the oceans and the climate worldwide, long into the future.

* Prof Iorns is a Law Professor working on environmental law and indigenous rights, who has won several awards for her research and teaching. Her IUCN work focuses on Antarctica and Southern Ocean protection and governance. 

How to cite: iorns, C.: Responsibility and guardianship for Southern Ocean governance, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1213, https://doi.org/10.5194/oos2025-1213, 2025.

Eddies are under sampled in the Weddell Sea, due to an extensive ice cover for large parts of the year. There are even fewer observations of eddies under ice, with none detailing the dynamic and thermodynamic interactions between them. Here we present novel observations of an eddy spinning down under an ice shelf. Two acoustically tracked profiling floats were deployed at 8^oW in the Antarctic Slope Current and drifted westward along the slope at 800m depth. One of the floats was captured by an anticyclonic eddy in the wake of Riiser-Larsen Ice shelf.  We postulate the eddy was generated by baroclinic instability due to the interaction of the Antarctic Slope Current with floating ice shelves. Trajectory data show the eddy propagated westward along the slope and ultimately became trapped under the Stancomb-Wills Ice Tongue, where the eddy spun down because of ocean-ice shelf stresses. Simple bulk mixing calculations are fitted to observations to explore the role of eddies under the ice shelf, in relation to an ‘Eddy-Ice-Pumping’ mechanism, and revealed that significant basal melting occurred. Subsequent mixing of the eddy’s cold and fresh core vertically in the upper water column, due to the Eddy-Ice-Pumping mechanism, resulted in a cold and fresh subsurface signal which was still evident downstream at the Filchner Trough three months later. Estimates of eddy contributions to basal melt and freshwater transport show eddies could have a significant impact on the stratification and thermocline depth downstream, potentially affecting the inflow of modified Warm Deep Water into the Filchner-Ronnie Ice Shelf. Since the Filchner-Ronnie Ice Shelf is where much of the source water for Antarctic Bottom Water is produced, eddy modified water column properties could affect the properties of this source water, and thus Antarctic Bottom Water. 

How to cite: Hancock, C., Speer, K., Janout, M., and Boebel, O.: Under Ice-Shelf Eddy at the Stancomb-Wills Ice Tongue, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1474, https://doi.org/10.5194/oos2025-1474, 2025.

As the world faces unprecedented environmental challenges, safeguarding both natural and cultural heritage of the ocean – ocean heritage – has become vital for fostering sustainable ocean stewardship. The Ocean Decade Heritage Network (ODHN) seeks to underscore the essential intersections between ocean heritage and marine science within the United Nations Decade of Ocean Science for Sustainable Development (2021-2030), advocating for heritage-informed governance that supports sustainable ocean policies.

Heritage provides a critical perspective on the complex relationships between humanity and the ocean. From tangible submerged landscapes and shipwrecks to intangible Indigenous maritime traditions, ocean heritage embodies extensive knowledge and practices that reveal the historical and ongoing connections between human societies and marine ecosystems. ODHN’s mission within the UN Ocean Decade aims to bridge disciplines, uniting marine science with heritage fields to promote cross-sectoral collaboration that enhances our understanding of the ocean and its historical narrative. This holistic approach encourages the integration of heritage insights into broader ocean governance and policy frameworks.

The presentation will illustrate how ocean heritage offers unique contributions directly aligned with the Decade’s goals. Integrating cultural heritage into ocean sciences enriches marine policies by embedding them within broader social and cultural contexts, thus fostering inclusive governance that respects the knowledge, values, and contributions of diverse communities. By weaving heritage considerations into ocean governance, ODHN promotes an approach that is both scientifically rigorous and culturally resonant.

ODHN’s interdisciplinary work resonates with the Decade’s emphasis on collaborative solutions and innovative methodologies. Integrating heritage into ocean science supports novel approaches, such as using archaeology to inform ecological studies and provide data for long-term time scales,  and incorporating traditional knowledge systems into conservation practices. This cultural perspective is essential to ensuring that the legacy of human-ocean interactions continues to shape sustainable practices, guiding scientific advancements that are attuned to both ecological imperatives and cultural values.

This presentation will highlight ODHN’s progress during the first half of the Decade, illustrating how ongoing initiatives contribute to a comprehensive understanding of ocean health and resilience. It will outline ODHN’s strategy for advancing a unified approach that merges natural and cultural heritage with societal goals and the 2030 Agenda, strengthening conservation efforts across disciplines. Additionally, it will address the challenges and best practices for fostering cross-disciplinary collaboration among heritage specialists, marine scientists, and policymakers, and discuss strategies for expanding engagement in heritage conservation within the Decade and beyond.

By emphasizing the foundational role of heritage in ocean sciences and governance, ODHN advocates for a future where cultural heritage is actively integrated into sustainable ocean stewardship. This approach affirms that ocean heritage is not simply a relic of the past but a dynamic, evolving foundation for resilience, positioning heritage as a vital asset in realizing the ambitious goals of the UN Ocean Decade

How to cite: Rey da Silva, A., Trakadas, A., Elkin, D., Scot-Ireton, D., Viduka, A., Kimura, J., Boswell, R., Collazo-Rivera, I., and Guerin, U.: The Role of Heritage in Ocean Science and Governance under the UN Ocean Decade, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-950, https://doi.org/10.5194/oos2025-950, 2025.