France's overseas territories - guardians of the ocean

Whether France's overseas territories border the Indian, Pacific or Atlantic Oceans, they are at the forefront of changes taking place in the oceans. Rising temperatures, endangered reefs and the pressure put on biodiversity mean these islands are like 'sentinels' as well as unique study sites and essential partners for research. For many years now, the CNRS has been involved in these territories, working alongside local authorities, scientists and residents. France's overseas territories embody an ocean science focused on issues like coral protection, coastal zone management or climate risk anticipation and jointly co-constructed with a focus on resilience. Let's take a look at three flagship projects in this area of the world.

Science comes into port in Martinique

In Fort-de-France, scientific research has found itself in an unexpected place - at the heart of Martinique's major seaport. This site is key to the island's economy and has also become an unexpected sanctuary for three protected coral specieswhich settled on the rockfill of a former construction site. These coral colonies developed in very unfavourable conditions, thus revealing an astounding resilience that is intriguing researchers.

However, now a new building expansion project is threatening their survival. "The port found itself faced with an unprecedented question - how can we reconcile economic development and biodiversity protection?" sums up Jean-Raphaël Gros-Desormeaux, CNRS researcher and director of the Powers, History, Slavery, Atlantic Caribbean Environment Laboratory (PHEEAC)1 . In response, the port has implemented a scientific strategy in partnership with the CNRS, thus breaking with the past tradition of relying on regulatory studies generally carried out by consulting companies.

• 1CNRS/Université des Antilles.

The port has funded an experimental platform for the conservation and restoration of reef functions, which is schedule to be operational by the end of 2025. "It'll be the first of its kind in the Caribbean. We'll work on their propagation and gradual acclimatisation there before replanting the corals elsewhere around the island," explains the researcher. The laboratory is committed to a twenty-year programme and will host environmental DNA research to find out more about the capacity of these corals to thrive in such a polluted environment.

This scientific infrastructure comes in the framework of a broader transformation, with the port also a core subject for a socio-ecological transition observatory led by the PHEEAC. "We've set up a multi-stakeholder governance system with residents, associations, scientists and so on that is able to debate issues in thematic forums. This changes the overall balance even though all final decisions are taken by the port," continues the researcher.

This initiative has paved the way for more collaboration, for example with Météo-France on a project to study effects of heat waves on port workers and another to set up a pilot power plant to enhance the island's energy independence. "The port is a leading stakeholder in the region. This partnership based on knowledge production could inspire other stakeholders on the island," he sums up.

50 years of climate observations in Polynesia

On the other side of the world, another island from France's overseas territories has similar concerns. For over fifty years, scientists at the Criobe laboratory1  in Moorea, French Polynesia, have been studying coral reefs to that extent that the Criobe's experimental station located on the edge of the lagoon is now considered an international reference for reef ecology.

"As well as monitoring work in French Polynesia, we have geopolitical importance in the Pacific thanks to our collaborations with our neighbours in Samoa, Tonga and Kiribati," explains Pierre Sasal, the CNRS researcher who directs the Criobe. The national observation service CORAIL monitors temperatures, rising sea levels, cyclones or pollution on the site. "A healthy reef also provides natural protection against strong swells and storms for populations."

However the Criobe does not just observe the situation, its researchers also take action in the field. Scientists are now developing experimental approaches to reef restoration under controlled conditions. Temperature, light, noise and other factors can be modulated to test resistance to environmental changes of corals or fish physiology and then hopefully identify the most resilient strains. The lab also works on innovation, with current projects involving the removal of algae and farming sea urchins or herbivorous fish to help corals recolonise a the reef once temperatures have dropped.

• 1CRIOBE (research centre of excellence focusing on coral reefs, CNRS/EPHE/University of Perpignan Via Domitia)

"Increasingly we're jointly developing projects with associations, fishermen and local communities," adds the researcher. A prime example of this is his laboratory's support for setting up traditional protected areas or 'rāhui'1 . Working with the Louis Malardé Institute2  the station also has plans to work on public health issues like ciguatera, a toxin that accumulates in fish, possibly making them dangerous or even deadly to eat. "We want to provide local answers to tangible problems in highly isolated contexts," adds Pierre Sasal. In this way, this work embodies the phrase 'Science - with and for society', echoing dynamics in other French overseas territories.

Supporting the reversal of unsustainable trends in French overseas territories

From corals to coastlines, from populations to public policy. Camille Mazé-Lambrechts takes an integrative and systemic approach to overseas territories. She is a CNRS political science research professor with at the Centre for Political Research at Sciences Po3  and also holds the Omega chair (Overseas Territories and Global Change), also at Sciences Po Paris. This chair results from a merger involving the Overseas Chair created by the 2017 Erom Act4  and the international research network APOLIMER. The merger was intended to broaden the original chair's scope to address the challenges of global change more effectively.

In this context, transdisciplinary research carried out in collaboration with local communities concentrates on the governance of island territories and on promoting the concept of socio-ecosystems. "With the Omega Chair, we're working at the interface between science, local communities and political decision-making," explains the researcher. There are multiple challenges, including producing useful knowledge for the territories, training the students, decision-makers and entrepreneurs of tomorrow, while also promoting and using knowledge and solutions from the overseas territories themselves. 

"France possesses the world's second largest exclusive economic zone and its overseas territories make the main contribution to it. But the ocean is not just a strategic resource for these territories. For them it's a place of life, culture and history," explains the researcher. That history has been marked by power struggles, colonial legacies, environmental pressures and inequalities which is why an open-minded approach bringing together the humanities and social sciences, economics and law, life and earth sciences, and public health is so important.

• 1These areas are traditionally managed by communities and alternate between periods of opening and closure, sometimes with a permanently protected core which allows for the sustainable regeneration of resources.
• 2The Louis Malardé Institute (ILM) is a public industrial and commercial establishment under the supervisory authority of French Polynesia's Minister of Health. The ILM carries out analysis, research and trade in the fields of health, the environment, hygiene and food.
• 3CEVIPOF (CNRS / Sciences Po Paris)
• 4A law on the true real state of equality between the overseas territories and mainland France.

In the projects Camille Mazé-Lambrechts coordinates and the theses she supervises in Mayotte, Polynesia, Réunion and Saint-Pierre-et-Miquelon, the research focus is on environmental regeneration, traditional usages and how these evolve, and political dynamics and institutional change in the context of global change. Multidisciplinary groups of 'scientists without borders' and a network of the chair's young ambassadors work in each of these territories, thus combining local roots with critical analysis and transformative action. "We need to leave behind a centralised view based on in mainland France now and instead recognise forms of knowledge, innovation and resilience from the territories themselves," insists Ms Mazé-Lambrechts. 

Finally, the chair highlights the importance of a systemic approach that naturally goes beyond the ocean alone. In this approach, particular importance is attached to socio-ecological continuities, political dynamics and identifying the levers and obstacles to the transition towards sustainability.

From the ocean to land - a shared destiny

Because what goes on in the oceans does not begin or end at the shore. In Mayotte, Moorea and Martinique, the resilience of reefs depends on what happens on land in terms of water quality, agricultural practices, land pressure, urbanisation, and so on. In return, healthy lagoons and mangroves provide protection from storms and erosion for local inhabitants.

This integrated vision featuring a science at the crossroads of ecological, social and political issues is increasingly adopted by projects set up in such locations. Overseas territories are actually not marginal areas – they are like 'look-outs' or places of alert, experimentation and innovation where new methods of practising science and implementing policy are being invented through a necessary shift in perspective.