Internal pH regulation facilitates in situ long-term acclimation of massive corals to end-of-century carbon dioxide conditions


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Gertraud.Schmidt [ at ] awi.de

Abstract

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 7.4. A growth response model based on pHcf mirrors the observed distribution patterns of this species in the field. We suggest Porites has the capacity to acclimate after long-time exposure to end-of-century reduced seawater pH conditions and that strong control over pHcf represents a key mechanism to persist in future oceans. Only beyond end-of-century pCO2 conditions do they face their current physiological limit of pH homeostasis and pHcf begins to decrease.



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Peer-reviewed
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Published
Eprint ID
43032
DOI 10.1038/srep30688

Cite as
Wall, M. , Fietzke, J. , Schmidt, G. M. , Fink, A. , Hofmann, L. C. , de Beer, D. and Fabricius, K. E. (2016): Internal pH regulation facilitates in situ long-term acclimation of massive corals to end-of-century carbon dioxide conditions , Scientific Reports, 6 , p. 30688 . doi: 10.1038/srep30688


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