Effects of seawater pH on growth and skeletal U/Ca ratios of Acropora digitifera coral polyps

Mayuri Inoue, Ryota Suwa, Atsushi Suzuki, Kazuhiko Sakai, Hodaka Kawahata

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)


The impact of ocean acidification caused by the increasing atmospheric CO2 has been studied in marine calcifiers, including hermatypic corals. However, the effect of elevated pCO2 on the early developmental life-cycle stage of corals has been little studied. In this study, we reared polyps of Acropora digitifera in seawater at pHT 6.55, 7.31, 7.64, 7.77, and 8.03, controlled by CO2 bubbling. We measured the dry weights of polyp skeletons after the 40-d experiment to investigate the relationship between the seawater aragonite saturation state and polyp growth. In addition, we measured skeletal U/Ca ratio to estimate their pH dependence. Skeletal weights of coral polyps increased with the aragonite saturation state and reached an apparent saturation plateau above pH 7.77. U/Ca ratios had a strong inverse relationship with pH and a negligible relationship with skeletal growth rate (polyp weight), suggesting that skeletal U/Ca could be useful for reconstructing paleo-pH.

Original languageEnglish
Article numberL12809
JournalGeophysical Research Letters
Issue number12
Publication statusPublished - Jun 1 2011
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)


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