Organism movement plays a crucial role in the transfer of genes, matter, and energy between habitats, both in marine environments and across the land-sea interface. The numerous fluxes resulting from the lifetime and trans-generational displacements of all marine species (from bacteria to whales), collectively referred to as Marine Functional Connectivity (MFC), underpins planetary health and diverse ecosystem services. However, awareness and integration of this connectivity in marine research, management and policy is still limited. Given surging environmental change, resource overexploitation, habitat loss and fragmentation, and the global transport of non-native species, accurately estimating and predicting MFC patterns is vital to support global policy goals aimed at conserving and restoring ocean biodiversity and function. This talk provides an overview of the current state of MFC research and identifies key challenges and future directions for this emerging field, critical for supporting truly multidisciplinary marine science for improved management and policy. Placing MFC research at the heart of marine environmental science and management promises to increase ecological and socio-economic resilience worldwide, and improve the sustainable use of ecosystems and resources, at sea and at the land-sea interface.

How to cite: Darnaude, A. M., Beger, M., Blanco, A., Costantini, F., Goldsborough, D., Hidalgo, M., López-López, L., Sturrock, A. M., Tanner, S. E., Teff Seker, Y., Türkmen, A., Volkaert, F., and Hunter, E.: Connectivity, at sea and at the land-sea interface: unveiling the overlooked role of marine biodiversity in Biosphere functioning, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-190, https://doi.org/10.5194/oos2025-190, 2025.

Understanding and enhancing marine functional connectivity (MFC) is essential to sustaining the resilience of Mediterranean coastal ecosystems. Seagrass meadows of Posidonia oceanica, in particular, play a pivotal role by supporting biodiversity, stabilizing coastlines, and facilitating nutrient cycling across fragmented marine habitats. This research leverages advanced hydrodynamic and seed dispersal models, alongside graph theory, to map out critical connectivity pathways for P. oceanica across the Balearic archipelago. Key connectivity hubs emerged, including Alcudia Bay as a primary “sink” area, and strong ecological bridges between islands (e.g., Mallorca-Menorca and Ibiza-Mallorca), which underscore the strategic importance of robust connectivity networks in maintaining ecosystem function. These findings directly inform the design and management of Marine Protected Areas (MPAs), identifying high-impact sites for restoration and conservation that can reinforce connectivity and amplify ecosystem resilience against environmental pressures. By applying an MFC perspective to seagrass conservation, this research provides a foundation for integrated land-sea management and supports sustainable blue growth and restoration strategies in the Mediterranean. The insights gained here guide policymakers and coastal managers toward science-based interventions that maximize ecological connectivity, contributing to the creation of a resilient, interconnected ocean ecosystem that supports both nature and society.

How to cite: Ospina-Álvarez, A., Pastor, A., de Juan, S., Terrados, J., Castejón, I., Mourre, B., and Catalán, I.: Connecting the dots in the Mediterranean: Harnessing Marine Functional Connectivity for resilient seagrass ecosystems, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-570, https://doi.org/10.5194/oos2025-570, 2025.

Sustainable fishery management requires a thorough knowledge of lifetime connectivity for exploited species to accurately define stocks and implement conservation and regulation measures at appropriate scales. This knowledge is especially critical in coastal regions in the Mozambique Channel, where communities rely on marine resources.

In Mozambique more than two-thirds of the rapidly growing population (33 million) live near the coast; penaeid shrimps are a vital component of the local food supply, livelihood and the country’s blue economy. However, shrimp catches have declined dramatically over the last two decades. This decline is attributed to increased artisanal fishing in estuarine nursery areas, removing juveniles before they can grow and recruit into the adult populations offshore, where the industrial fishery operates.

To understand larval connectivity and recruitment in the Sofala Bank region, we have employed a coupled biophysical model that accounts for adverse oceanographic conditions. Our research revealed that offshore eddies activity has an important role on coastal connectivity, and can have opposite effects depending on their locations, resulting in either larval recruitment, loss, or trapping.

These results improve our understanding of local marine functional connectivity patterns and show the necessity to study connectivity at a local scale to assist in developing targeted management strategies for adaptation and resilience, ensuring the sustainability of both commercial and artisanal fisheries.

How to cite: Malauene, B. S., Lett, C., Marsac, F., Moloney, C., and Roberts, M.: Understanding marine connectivity for sustainable fishery management: the case of coastal shrimp fisheries in Mozambique, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-144, https://doi.org/10.5194/oos2025-144, 2025.

Invasive species pose a serious risk to the biological, cultural, and economic value of marine ecosystems, a threat that is increasingly driven by maritime traffic as vessels transport species between domestic and international locations in our connected world. Network models are a useful technique for characterizing this functional connectivity in complex transport systems, and subsequent risk of invasion through these connections. Using New Zealand as a case study, we developed an 'epidemiological' decision-support model to simulate marine invasive species spread under various incursion and management scenarios. This process-based network model estimates relative incursion risks to domestic ports, aquaculture facilities, and coastal areas, factoring in vessel types (commercial, recreational, aquaculture), species growth, in-transit mortality, and recruitment. It tracks the flow of propagules through invasion stages—entrainment, transport, introduction, establishment, and population growth. We used the model to evaluate the effectiveness of pest control and vessel cleanliness on managing several marine pests over a 10-year period, assessing (1) how initial incursion sites affect spread, (2) dominant pathways and downstream risks, and (3) the impact of management interventions on detection and containment. Our findings highlight that vessel type and network position significantly influence translocation distance and intensity. Early simulations suggest that even localized measures, like vessel cleanliness or pest control, can reduce nationwide outbreak severity. The web-based tool, marPEST, enables stakeholders to explore and compare incursion scenarios, guiding biosecurity monitoring and intervention strategies at national scales. This model can be adapted for other regions and supports proactive management of invasive species, preserving ecological, cultural, and economic values.

How to cite: Treml, E., Pastor Rollan, A., Hilliam, K., Faubel, C., Davidson, I., Floerl, O., Welsh, M., Botero, J., and Stevenson, S.: Connected by maritime traffic: Network modelling to support understanding and management of marine biosecurity risk, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-814, https://doi.org/10.5194/oos2025-814, 2025.

The importance of ecological connectivity is being recognized in most major international fora dealing with biodiversity conservation, such as the Global Biodiversity Framework (GBF), the agreement on Biodiversity Beyond National Jurisdiction, and the regional environmental management plans for deep-sea mining by the International Seabed Authority. However, this recognition is currently not well-coupled with implementation in the oceans. For example, connectivity metrics included in the monitoring framework of the GBF have not been tested or applied in the ocean and in many instances are not even appropriate for estimating MFC specifically. I will present the current state of the incorporation of MFC in global conservation targets. I will then address some of the gaps and limitations for assessing MFC in the high seas and the deep ocean, particularly given the limited information on species distributions and life histories of deep sea species. I will provide examples of studies on connectivity that have direct implications for the design of networks of marine protected areas in the deep ocean and some of the tools and approaches that are possible to use. I will provide ideas on future directions to address the gap between the science of connectivity and its implementation in the management and conservation of the high seas and the deep ocean.

How to cite: Metaxas, A.: Applying MFC knowledge to meet global conservation targets for the deep and high seas, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-324, https://doi.org/10.5194/oos2025-324, 2025.

Marine Functional Connectivity (MFC) is a dynamic ecosystem process encompassing all the flows (of individuals, genes, matter and energy) driven by changes in the distribution and movement of marine organisms at sea and across the land-sea-air interface. Continuing advances in MFC understanding enhance our ability to evaluate the status, trends, and variability in marine species abundance, the drivers of change, and the role of marine species movement in the functioning of the biosphere. Ultimately, good knowledge of MFC is fundamental to advance models and forecasts of species and ecosystem distributions and resilience, and to develop scenarios that are possible outcomes of policy decisions. This talk explores how MFC knowledge can best improve the design of effective strategies for the sustainable and equitable use of marine ecosystems and resources. It summarizes practical transdisciplinary findings from several expert groups, convened in 2024 by the European COST Action/UN-Ocean Decade project SEA-UNICORN, the O-CONNECT working group of the French OMER GDR, and the UN-Ocean Decade Programme Marine Life 2030 to initiate the co-design of “the connectivity science and decision-making tools we need for the ocean we want”. Bringing together over 80 scientists, policymakers, and stakeholders from 22 countries, this initiative led to the production of key recommendations on how best to advance MFC data production and use to enhance: (1) Marine Protected Area design and management; (2) fisheries management; (3) blue economy development; (4) integrated management at the land-sea interface; (5) coastal and marine restoration; and (6) deep seas and high seas exploration and management.

How to cite: Darnaude, A., Guizien, K., Reisser, C., Metaxas, A., Bastide, L., Blanco, A., Boemare, C., Glyki, E., Mahevas, S., d'Agata, S., Eson, C., Hunter, E., Volckaert, F., De Wit, R., Pérez-Ruzafa, A., Pioch, S., Lyons, Y., Mackelworth, P., Teff-Seker, Y., and Muller-Karger, F.: The "why and how" of marine functional connectivity for sustainable development, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-667, https://doi.org/10.5194/oos2025-667, 2025.