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Effects of seawater pH on growth and skeletal U/Ca ratios of Acropora digitifera coral polyps
Author(s) -
Inoue Mayuri,
Suwa Ryota,
Suzuki Atsushi,
Sakai Kazuhiko,
Kawahata Hodaka
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl047786
Subject(s) - ocean acidification , seawater , aragonite , coral , hermatypic coral , saturation (graph theory) , biology , calcite , chemistry , environmental chemistry , mineralogy , ecology , mathematics , combinatorics
The impact of ocean acidification caused by the increasing atmospheric CO 2 has been studied in marine calcifiers, including hermatypic corals. However, the effect of elevated p CO 2 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 pH T 6.55, 7.31, 7.64, 7.77, and 8.03, controlled by CO 2 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.