MaHeWa: Understanding the Threats Posed by Marine Heatwaves to French Overseas Territories in the Pacific; Co-developing Decision Support Tools and Adaptation Solutions
Summary: 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 and practical decision-support tools and sustainable mitigation strategies.
Marine heatwaves are prolonged periods of extreme ocean temperatures that can have devastating effects on marine ecosystems, such as massive coral bleaching, mortality of coastal species, and toxic algal blooms. The intensity and frequency of MHWs are expected to increase in the future, posing a growing threat to FOT societies that rely heavily on marine resources.
Effective mitigation solutions will only be feasible if they are based on solid knowledge of the anticipated impacts of MHWs. However, such information is largely lacking for Pacific FOTs, and MaHeWa aims to mobilize French teams to address this gap. To this end, this interdisciplinary project brings together a consortium of internationally recognized climatologists, oceanographers, biologists, anthropologists, and economists, based in France and at overseas institutes and universities. These teams will work together to achieve major advances in understanding the characteristics and impacts of MHWs on socio-ecological systems in the FOTs.
More specifically, MaHeWa will examine the characteristics of past and future MHWs around these territories, the physical processes driving them, and the limits of their predictability. It will study fine-scale coastal processes that shape MHW signatures in lagoons with contrasting geomorphologies, using a combination of observations and high-resolution numerical modeling tools. The project will assess the sensitivity and adaptability of coral reefs and the vulnerability of species used in mariculture through laboratory and in-situ experiments. MaHeWa will evaluate mitigation and restoration solutions based on thermotolerance markers and species resilience enhancement. It will also improve our understanding of the impact of MHWs on the risk of ciguatera poisoning using a multi-scale approach from laboratory to lagoon. MaHeWa will 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 of health and marine resources. Together, they will co-develop decision-support tools: short-term MHW alert systems, health alert networks, and long-term vulnerability maps at an appropriate spatial scale for management. They will co-create action plans for crisis management and public policies on environmental and health issues. Finally, MaHeWa will enhance and test innovative, nature-based solutions to counter habitat degradation and ensure food security. It will engage the public through innovative activities in close collaboration with local associations.
MaHeWa is structured around 5 Work Packages and 3 cross-cutting tasks, involving 14 “partners” (research institutes, universities, territorial managers, and public administrations) and 19 research units. The consortium builds partly on existing collaborations but will establish new links, opening 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 and bring together researchers, institutions, and managers with a shared goal. It will achieve significant advances in understanding MHW characteristics and their anticipated impacts on the FOTs. Through strong links with operational forecasting actors, it will ensure the effectiveness and sustainability of the tools developed.
