Laboratory experiments testing the ability of corals to tolerate environmental conditions predicted for the next 50-100 years have been widely used to determine whether and how coral ecosystems will persist into the future; however, such experiments continue to produce mixed results that in part reflect difficulties in adequately (or consistently) replicating complex environmental and ecological interactions. These experiments are certainly informative, as they enable us to identify the effect of one or a few variables. Still, in isolation, they are unable to account for the implications of species' capacity for acclimatization (and adaption) in natural environments. Researchers have increasingly turned to examining corals which are already acclimatized to present-day extreme habitats, such as coral species that populate super-heated shallow reef flats (e.g., Shamberger et al., 2014), mangrove systems (Yates et al., 2014) and/or naturally `acidic' waters associated with CO₂-vent sites (Hall-Spencer et al., 2008; Rodolfo-Metalpa et al., 2011; Fabricius et al., 2011), i.e. conditions predicted to become normal for most reefs in the future.

In this context of scientific research, the SuperNatural project is part of a wider effort by the scientific community to predict the fate of coral reefs in a high CO2 world. As part of this research priority, the IRD Institut de Recherche pour le Développement has been awarded two ANR projects to study coral reefs living in CO2 resurgences in PNG. At the same time, partners at the UTS University of Technology of Sydney had previously worked on corals living in mangroves in the Seychelles, have established a fruitful collaboration with the IRD. An initial joint project was completed in February 2016. During this fieldwork, we collected environmental and physiological data to test the effectiveness of the Bouraké mangrove site as a natural laboratory for studying the effect of global change on coral populations. This initial study became the main topic for the IRD team organising Supernatural.

Our main hypothesis is that many marine species previously suggested (using a laboratory approach) to be sensitive to OA can acclimatize and potentially adapt to future conditions. The evidence for this hypothesis is that several reef-forming coral species thrive well at the mangrove in Bourake where pH, oxygen and temperature conditions are similar to future climate scenarios, thus suggesting that they can acclimate or even adapt to this naturally extreme environment.

Since our first investigation at the semi-enclosed Bouraké lagoon, a specific research theme has been developed at UMR Entropie using this unique site as a natural laboratory. SuperNatural is the first research project on this theme. It has enabled scientists to fully characterise the study sites and obtain the data needed to progress towards a better understanding of the Bouraké system.