Camp E. F. auteur aut IRD Nitschke M. R. auteur aut IRD Rodolfo-Metalpa Riccardo auteur aut IRD Houlbrèque Fanny auteur aut IRD Gardner S. G. auteur aut IRD Smith D. J. auteur aut IRD Zampighi M. auteur aut IRD Suggett D. J. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Coral reefs are deteriorating under climate change as oceans continue to warm and acidify and thermal anomalies grow in frequency and intensity. In vitro experiments are widely used to forecast reef-building coral health into the future, but often fail to account for the complex ecological and biogeochemical interactions that govern reefs. Consequently, observations from coral communities under naturally occurring extremes have become central for improved predictions of future reef form and function. Here, we present a semi-enclosed lagoon system in New Caledonia characterised by diel fluctuations of hot-deoxygenated water coupled with tidally driven persistently low pH, relative to neighbouring reefs. Coral communities within the lagoon system exhibited high richness (number of species = 20) and cover (24-35% across lagoon sites). Calcification rates for key species (Acropora formosa, Acropora pulchra, Coelastrea aspera and Porites lutea) for populations from the lagoon were equivalent to, or reduced by ca. 30-40% compared to those from the reef. Enhanced coral respiration, alongside high particulate organic content of the lagoon sediment, suggests acclimatisation to this trio of temperature, oxygen and pH changes through heterotrophic plasticity. This semi-enclosed lagoon therefore provides a novel system to understand coral acclimatisation to complex climatic scenarios and may serve as a reservoir of coral populations already resistant to extreme environmental conditions. specialized NOUVELLE CALEDONIE 036 032 021 7 art. 2434 [9 p.] 2017 2045-2322 https://www.documentation.ird.fr/hor/fdi:010070181 10.1038/s41598-017-02383-y 2045-2322 [F B010070181] https://www.documentation.ird.fr/hor/fdi:010070181 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers17-06/010070181.pdf IRD - Base Horizon / Pleins textes 2017-07-03 2018-01-02 fdi:010070181 fre