Climate-resilient corals : Tara Coral, a major scientific expedition in the Coral Triangle
Earth
Ten years after the launch of Tara Pacific and in a context of increasing coral bleaching, the scientific schooner Tara is leaving its home port of Lorient for its next expedition: Tara Coral. For 18 months, Tara will navigate through the Coral Triangle — the true Amazon of the Ocean — to understand why and how certain corals withstand global warming, and to help guide future coral conservation strategies.
The Tara Pacific expedition (2016-2018) studied reef biodiversity and its response to climate change and human pressures. The Tara Cora expedition (2026-2028) continues this work with a transdisciplinary approach, in collaboration with local stakeholders, in an area that had not been studied before: the Coral Triangle. What scientists discover could have a fundamental impact on conservation strategies around the world and in this Amazon of biodiversity.” Romain Troublé, Chief Executive Officer of the Tara Ocean Foundation
CORALS RESISTANT TO CLIMATE WARMING
“Unlike previous studies conducted at the global or basin scale, Tara Coral focuses on the only major reef region where hard coral cover has remained relatively stable despite strong warming trends. This provides an extraordinary natural laboratory for identifying the mechanisms of resilience.” Paola Furla, Scientific Director, Université Côte d’Azur
Although they cover only 0.2% of the ocean’s surface, coral reefs host ~25% of known marine biodiversity. True oceanic oases, they offer refuge, food, and habitat, and provide numerous ecosystem services that support more than 500 million people—mostly in the Pacific Ocean—with an estimated value of over USD 2.7 trillion per year (Costanza, R. et al., 2014).
More than 40% of coral species are threatened with extinction, facing both global pressures (rising temperatures, ocean acidification, sea-level rise) and local pressures (destructive fishing practices and overfishing, intensive coastal development, land-based pollution). Unlike many other regions of the world where climate warming has triggered widespread coral bleaching, the reefs of the Coral Triangle have thus far maintained their coral cover.
This region of the western Pacific, spanning 6 countries across 5.7 million km², is a true biodiversity hotspot. The Coral Triangle contains one-third of the world’s coral reefs and harbors exceptionally high diversity, including about three-quarters of all known coral species (approximately 600 species). A conservation priority with fragmented scientific data, the Coral Triangle represents a strategic challenge for coral conservation in the face of environmental, social, and economic pressures.
To understand the mechanisms underlying this thermotolerance and identify the corals of tomorrow, the Tara Ocean Foundation and more than 40 scientific partners have designed the transdisciplinary Tara Coral expedition.
TARA CORAL: A MAJOR SCIENTIFIC EXPEDITION
“The time is no longer only for documenting trends and the decline of coral reefs. The Tara Coral expedition aims to uncover the secret of corals that resist climate warming in the Coral Triangle. Their past exposure to thermal stress, the effect of internal waves, their genetics, their algal symbionts, their microbiome, their diversity, and the way they organize themselves: these are all avenues the expedition will explore to understand what protects the reefs.” Serge Planes, Scientific Director, CNRS Research Director
The Tara Coral expedition will test several hypotheses to explain this phenomenon of resistance:
- a greater diversity of organisms within ecosystems
- the presence of more resistant species
- a selection of individuals pre-adapted to climate change due to their local environment and climatic history
- the upwelling of cooler waters (micro-upwelling)
● A global approach to the ecosystem
For 18 consecutive months, the schooner Tara will navigate through the Coral Triangle along a 30,000-nautical-mile route — more than 50,000 km — crossing 6 countries and making a total of 26 stopovers. Tara will remain 35 days at each of the 10 planned sampling sites, and the scientific teams will adopt a holistic approach to the ecosystem, focusing on four coral genera (with complementary analyses to characterize the biodiversity at large) : Acropora, Millepora, Porites, and Pocillopora.
C. Millepora spp. (© Lauric Thiault ) ; D. Pocillopora spp. (© Philippe Bourjon)
A comprehensive approach is essential in order to understand which species exist, how they adapt, and how they interact with each other and with their environment. To this end, the scientific work is organized into four components supported by a comprehensive, multi-method field protocol.
Description of the environmental context
Environmental DNA (eDNA) sampling to describe the overall biodiversity of the reef using a sampling robot, and photogrammetry to describe the 3D structure of the reef.
Characterization of the complexity of the coral holobiont
Extensive sampling of coral species and associated habitats (coral fragments, algae, sediments, water, aerosols, and sponges) to generate diverse datasets that resolve holobiont structure and function, with a particular focus on symbiosis.
Characterization of heat stress resistance
Using a CBASS (Coral Bleaching Automated Stress System) system installed on board Tara, coral fragments from various colonies are placed in separate tanks and exposed to four different temperature levels (no heat stress, low, moderate, or high heat stress) in order to test the resistance of corals to heat stress and detect biomarkers of corals that are more resistant to bleaching. This provides a standardized diagnostic heat stress phenotype.
Geochemistry for paleoclimate and paleogenomics
Coring of massive corals to quantify growth parameters, reconstruct past climate, and analyze long-term genomic responses.
“The Tara Coral expedition is unique due to its combination of scientific scope, methodological standardisation, geographical focus, and integration between disciplines and partners. Now is the time to act to understand, preserve, and strengthen the resilience of coral reefs.” Christian Voolstra, Scientific Director, Professor at Konstanz University
● A transdisciplinary expedition designed in local collaboration
One of the unique features of the Tara Coral expedition is its comprehensive scientific approach, which brings together a range of scientific expertise: divers, oceanographers, marine biologists, eDNA specialists, genomicists, bioinformaticians, microbiologists, photogrammetry specialists, microplastics specialists, paleoclimatologists, biochemists, modellers, and many others.
Tara Coral is the result of close local collaboration involving 67 scientists, 22 women and 45 men, from more than 40 scientific partners, including 11 from the Coral Triangle.
● Expected scientific results and prospects
At the end of this expedition, it is expected that there will be a better understanding of the thermotolerance of corals and the resilience of reefs in the Coral Triangle area. This will enable the development of standardized protocols, the creation of open-access resources, the transfer of expertise to local stakeholders (local actors, scientists, managers, policymakers, educators), and the raising of awareness and mobilization of key players.
In the longer term, the aim is to strengthen reef protection and restoration capabilities in key biodiversity areas by identifying naturally resistant coral populations and analyzing the mechanisms, characteristics, and environmental conditions that underlie their robustness.
AN ADVENTURE FOR SCIENCE AND SOCIETY
● Sharing, a societal challenge
Each of the schooner's expeditions provides opportunities to engage society, create innovative tools to reach new audiences, and share the excitement of discovery. The schooner is a wonderful vehicle for telling this story.
The “Science-to-citizen” program will revolve around two key awareness-raising tools—a traveling exhibition dedicated to the Tara Coral mission and a scientific mediation tool focused on the global importance of coral ecosystems—which will be developed in collaboration with local actors to ensure cultural relevance, inclusiveness, and sustainable use.
● Strengthening conservation policies at the international level
Conservation issues will be given high priority by working alongside governments and local stakeholders to identify and protect those reefs that are most resistant to global warming. The Tara Ocean Foundation will organize several science-to-policy workshops during Tara Coral's stopovers and will actively participate in international summits working to conserve coral reefs.
● Sailing to create
Because art is part of the Foundation's DNA, artists will embark on residencies alongside scientists. A dozen creators from various disciplines, selected through a call for applications and partnerships with institutions of excellence such as IRCAM and Villa Kujoyama, will take turns on board throughout the mission. This will be a unique period of immersion and experimentation, during which the artists will imagine new relationships with the ocean and coral in collaboration with local artists.
