MaHeWa is dedicated to understanding and forecasting the impacts of marine heatwaves (MHWs) on the socio-ecological systems of French overseas territories (FOT) in the South Pacific. Working closely with territorial managers in New Caledonia, Wallis and Futuna, and French Polynesia, the project aims to co-develop reliable decision-support tools and sustainable mitigation strategies.
Marine heatwaves (MHWs) are prolonged episodes of extreme ocean temperatures that can have devastating effects on marine ecosystems, such as massive coral bleaching, coastal species mortality, and toxic algal blooms. The intensity and frequency of MHWs are expected to increase in the future, posing a growing threat to FOT societies, which heavily depend on marine resources. Effective mitigation solutions will only be feasible if based on a solid foundation of knowledge about MHW impacts, which is largely lacking for Pacific FOTs. MaHeWa aims to mobilize French teams to address this gap. To this end, the interdisciplinary project brings together a consortium of internationally recognized climatologists, oceanographers, biologists, anthropologists, and economists based in France and overseas research institutions. These teams will work together to make major advances in understanding the characteristics and impacts of MHWs on socio-ecological systems in FOTs.
More specifically, MaHeWa will study the characteristics of past and future MHWs around these territories, the physical processes driving them, and their predictability limits. It will examine fine-scale coastal processes that define MHW signatures in lagoons with contrasting geomorphologies, combining observations with high-resolution numerical modeling tools. The project will assess coral reef sensitivity and adaptability, as well as the vulnerability of mariculture species, through laboratory and in-situ experiments. MaHeWa will evaluate mitigation and restoration solutions based on thermotolerance markers and enhancing species robustness. Additionally, it will improve assessment of MHW impacts on ciguatera poisoning risk through a multi-scale approach from lab to lagoon. MaHeWa will also assess the socio-economic resilience of these territories to MHWs, examining how “risk cultures” developed to manage extreme events are constructed, transformed, and negotiated, and will produce biocultural risk indicators.
Throughout the project, MaHeWa will foster close dialogue between scientists and the project’s partner territorial managers responsible for health and marine resources. Together, they will co-design decision-support tools: short-term MHW alert systems, health alert networks, and long-term vulnerability maps at spatial scales suitable for management. They will also develop crisis management action plans and public policies for environmental and health issues. Finally, MaHeWa will enhance and test innovative, nature-based solutions to counter habitat degradation and ensure food security. Public outreach will be promoted through innovative activities closely linked with local associations.
MaHeWa is structured around 5 Work Packages (WPs) and 3 cross-cutting tasks, involving 14 “partners” (research institutes and universities, territorial managers, and public administrations) and 19 research units. The consortium builds on existing collaborations but will establish new links, creating collaborative research opportunities across territories. The innovative nature and strength of MaHeWa lie in its interdisciplinary and transdisciplinary approach; it will mobilize the French research community around a major challenge, bringing together researchers, institutions, and managers with a shared goal. MaHeWa will achieve significant advances in understanding MHW characteristics and their expected impacts on FOTs. Its strong links with operational forecasting entities will ensure the effectiveness and durability of the tools developed.
