Meunier V. auteur aut IRD Geissler L. auteur aut IRD Bonnet Sophie auteur aut IRD Radecker N. auteur aut IRD Perna G. auteur aut IRD Grosso O. auteur aut IRD Lambert C. auteur aut IRD Rodolfo-Metalpa Riccardo auteur aut IRD Voolstra C. R. auteur aut IRD Houlbrèque Fanny auteur aut IRD text journalArticle eng text/pdf born digital access Ocean acidification is posing a threat to calcifying organisms due to the increased energy requirements of calcification under high CO2 conditions. The ability of scleractinian corals to cope with future ocean conditions will thus depend on their ability to fulfil their carbon requirement. However, the primary productivity of coral holobionts is limited by low nitrogen (N) availability in coral reef waters. Here, we employed CO2 seeps of Tutum Bay (Papua New Guinea) as a natural laboratory to understand how coral holobionts offset their increased energy requirements under high CO2 conditions. Our results demonstrate for the first time that under high pCO(2) conditions, N assimilation pathways of Pocillopora damicornis are jointly modified. We found that diazotroph-derived N assimilation rates in the Symbiodiniaceae were significantly higher in comparison to an ambient CO2 control site, concomitant with a restructured diazotroph community and the specific prevalence of an alpha-proteobacterium. Further, corals at the high CO2 site also had increased feeding rates on picoplankton and in particular exhibited selective feeding on Synechococcus sp., known to be rich in N. Given the high abundance of picoplankton in oligotrophic waters at large, our results suggest that corals exhibiting flexible diazotrophic communities and capable of exploiting N-rich picoplankton sources to offset their increased N requirements may be able to cope better in a high pCO(2) world. specialized CO2 seeps coral holobiont DDN assimilation heterotrophy N-2 fixation ocean acidification picoplankton symbiotic diazotrophs PAPOUASIE NOUVELLE GUINEE 034 084 020 30 22 5888-5899 2021 0962-1083 https://www.documentation.ird.fr/hor/fdi:010083213 10.1111/mec.16163 0962-1083 [F B010083213] https://www.documentation.ird.fr/hor/fdi:010083213 https://www.documentation.ird.fr/intranet/publi/2021-11/010083213.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2021-11-10 2026-01-30 fdi:010083213 fre