David Mouillot: Fish and People

It’s hard to get him to talk about himself. David Mouillot prefers to skim over his career in broad strokes to get straight to his new project: assessing the role of coastal marine resources in the development of rural regions in East Africa. These areas have been affected for the past thirty years by land desertification caused by climate change. It’s a major research project for which he has just been awarded a five-year ERC Advanced Grant worth 2.5 million euros.“My hypothesis is that coastal villages that have turned to the sea and have been able to protect their marine resources are faring better in terms of economic and human development than their counterparts that have relied solely on agriculture and livestock as their main resources, ” explains the researcher at the Marbec laboratory. This question builds on his ongoing work on the interplay between climate change and socioeconomic factors on marine ecosystems.

The first step in this research is to identify the villages to be studied in the three countries under consideration: Madagascar, Tanzania, and Mozambique. To track the socioeconomic trajectories of coastal villages, the researcher has opted for aerial observation—that is, the analysis of satellite images taken between 1990 and 2024.“This allows us to look back in time and track changes in infrastructure, light intensity, and land use—all indicators of the villages’ economic development. The idea is to identify the ‘bright spots’ and ‘dark spots’—in other words, the villages with successful development trajectories and those caught in a cycle of poverty.”

Nature-based solutions

This large-scale spatial approach will be carried out with extensive use of artificial intelligence applied to satellite imagery. Then, once the villages have been identified,“there is an important phase of field surveys to verify our hypothesis and understand the drivers of success. ” All of these projects are made possible by the ERC’s material and human resources: five engineers specializing in AI applied to satellite imagery and a postdoctoral researcher for the socioeconomic analysis of the selected villages. The socio-ecological modeler is delighted with this interdisciplinary team.

David Mouillot, who holds a Ph.D. in biomathematics, admits that he was not destined for either marine ecology or socio-ecology. But a lot has happened in his career since then. Appointed as an associate professor in Montpellier in 2001—“the day the Twin Towers fell,” he recalls—he has remained at the Montpellier marine ecology laboratory ever since.“I started by modeling the impact of fishing on fish stocks and biodiversity. Our results were predictable and trivial: the more fish were caught, the fewer there were,” he recalls critically.

Then the shift in environmentalism that took place in 2006 in response to the impacts of climate change inspired him. “The 2003 heat wave in France and the excess deaths it caused marked the beginning of a profound shift in awareness—the dawn of an environmentalism rooted in climate issues.” 

In 2010, thanks to a European Marie Curie fellowship, David Mouillot went to James Cook University in Australia to work in a socio-ecology laboratory to quantify the impact of socio-ecological changes on coral reef systems.“This team was a pioneer in the nature-based solutions approach, which has since become widespread. The idea that protecting nature contributes to human well-being was a turning point for me.”

The Blue Economy

And, when he considers the promises of the blue economy, the hypothesis that the sustainable use of marine resources can drive economic development inspires his ERC project. His goal is to “better predict the link between ecosystem health and poverty in rural coastal communities.”

Returning to his career, among the honors David Mouillot has not mentioned, it is worth noting that he was a junior and then senior member of the Institut universitaire de France (IUF) between 2009 and 2024, received the CNRS Bronze Medal in 2011, and has been among the world’s most-cited researchers in ecology and the environment since 2016.

It’s also impossible not to mention the new environmental DNA tools he has developed to study marine ecosystems. Made possible by the automation of sequencing, the technique relies on the analysis of DNA filtered from water. Having been tested in freshwater, his team has been applying this technique to the marine environment since 2016. With the creation of a joint laboratory between Marbec and the company SpyGen, he has established a reference database for the Mediterranean that now includes nearly 80% of the barcodes for the 600 listed fish species.

For his ERC project, David Mouillot also wants to assess—using environmental DNA—the marine biodiversity off the coast of the villages under study,“to see if there is a link between the villages’ level of development and the nearby coastal biodiversity, in the hope of finding a reason for optimism. ” And the humanist ecologist dreams that a virtuous cycle might emerge from sustainable fishing.