biostudies-literatureWall MAustrian Science Fund FWF30688https://www.ebi.ac.uk/biostudies/studies/S-EPMC4967918biostudies-literatureUnknown6The resilience of tropical corals to ocean acidification depends on their ability to regulate the pH within their calcifying fluid (pHcf). Recent work suggests pHcf homeostasis under short-term exposure to pCO2 conditions predicted for 2100, but it is still unclear if pHcf homeostasis can be maintained throughout a corals lifetime. At CO2 seeps in Papua New Guinea, massive Porites corals have grown along a natural seawater pH gradient for decades. This natural gradient, ranging from pH 8.1-7.4, provides an ideal platform to determine corals' pHcf (using boron isotopes). Porites maintained a similar pHcf (~8.24) at both a control (pH 8.1) and seep-influenced site (pH 7.9). Internal pHcf was slightly reduced (8.12) at seawater pH 7.6, and decreased to 7.94 at a site with a seawater pH of 7.4Scientific reportsInternal pH regulation facilitates in situ long-term acclimation of massive corals to end-of-century carbon dioxide conditions.PMC4967918J 3667Fabricius KEWall MSchmidt GMde Beer DHofmann LCFietzke JFink AfalseInternal pH regulation facilitates in situ long-term acclimation of massive corals to end-of-century carbon dioxide conditions.The resilience of tropical corals to ocean acidification depends on their ability to regulate the pH within their calcifying fluid (pHcf). Recent work suggests pHcf homeostasis under short-term exposure to pCO2 conditions predicted for 2100, but it is still unclear if pHcf homeostasis can be maintained throughout a corals lifetime. At CO2 seeps in Papua New Guinea, massive Porites corals have grown along a natural seawater pH gradient for decades. This natural gradient, ranging from pH 8.1-7.4, provides an ideal platform to determine corals' pHcf (using boron isotopes). Porites maintained a similar pHcf (~8.24) at both a control (pH 8.1) and seep-influenced site (pH 7.9). Internal pHcf was slightly reduced (8.12) at seawater pH 7.6, and decreased to 7.94 at a site with a seawater pH of 7.42016-01-01T00:00:00Z2016 Aug2026-05-05T15:42:01.372Z2019-03-27T02:19:34ZS-EPMC49679182747796310.1038/srep30688