TY - JOUR
T1 - The influence of seawater calcium ions on coral calcification mechanisms
T2 - Constraints from boron and carbon isotopes and B/Ca ratios in Pocillopora damicornis
AU - Giri, Sharmila J.
AU - Swart, Peter K.
AU - Pourmand, Ali
N1 - Funding Information:
We thank P. Gillette and T. Capo for providing us with space in the University of Miami's experimental hatchery facility to conduct these experiments. We also thank Q. Devlin, K. Erceg, S. Shedd, B. Hall, S. Ahearn, T. Longbottom, P. Staudigel, K. Galvez, S. Billings, D. Stommes, and A. Bardales for helping with the experimental component of this research and A. Saied, S. Ahearn, P. Staudigel S. Murray, S. Mehterian, and C. Kaiser for their assistance in the lab with sample preparation and analyses. We especially thank M. Henehan for analyzing the coral standard and his helpful suggestions on optimizing the analytical procedure and G. Foster and R. Moyer for generously sharing the BIG-E, BIG-D and UMD boron isotope standards. A. Sharifi provided the Porites lutea coral specimen from the Persian Gulf. We also thank O. Branson and an anonymous reviewer for carefully reviewing our manuscript and for providing thoughtful and critical feedback. Discussions with T. McConnaughey and N. Allison greatly improved our calcification model under different [Ca2+]. Finally, we thank the Geological Society of America, the David Rowlands Fellowship from the University of Miami's Rosenstiel School of Marine and Atmospheric Sciences, and the University of Miami's Stable Isotope Lab, which provided financial support of this research. This study was in part funded by the NSF grant #1537727 to P.K. Swart and A. Pourmand.
Funding Information:
We thank P. Gillette and T. Capo for providing us with space in the University of Miami's experimental hatchery facility to conduct these experiments. We also thank Q. Devlin, K. Erceg, S. Shedd, B. Hall, S. Ahearn, T. Longbottom, P. Staudigel, K. Galvez, S. Billings, D. Stommes, and A. Bardales for helping with the experimental component of this research and A. Saied, S. Ahearn, P. Staudigel S. Murray, S. Mehterian, and C. Kaiser for their assistance in the lab with sample preparation and analyses. We especially thank M. Henehan for analyzing the coral standard and his helpful suggestions on optimizing the analytical procedure and G. Foster and R. Moyer for generously sharing the BIG-E, BIG-D and UMD boron isotope standards. A. Sharifi provided the Porites lutea coral specimen from the Persian Gulf. We also thank O. Branson and an anonymous reviewer for carefully reviewing our manuscript and for providing thoughtful and critical feedback. Discussions with T. McConnaughey and N. Allison greatly improved our calcification model under different [Ca 2+ ]. Finally, we thank the Geological Society of America, the David Rowlands Fellowship from the University of Miami's Rosenstiel School of Marine and Atmospheric Sciences, and the University of Miami's Stable Isotope Lab, which provided financial support of this research. This study was in part funded by the NSF grant # 1537727 to P.K. Swart and A. Pourmand.
PY - 2019/8/1
Y1 - 2019/8/1
N2 - In order to better understand the response of coral calcification to changes in seawater chemistry, fragments of the coral Pocillopora damicornis were grown in seawater with varying [Ca2+]. Using a combined trace element (B/Ca) and stable isotope (δ11B, δ13C) approach, this paper explores the effect of seawater calcium concentrations ([Ca2+]SW) on coral calcification mechanisms and describes the manipulation of the extracellular calcifying fluid (ECF) pH (pHECF), saturation state (ΩECF) and dissolved inorganic carbon (DIC) speciation of the ECF. In these experiments, increases in [Ca2+]SW did not significantly influence calcification rates but caused the skeletal B/Ca ratio to significantly increase. To explain these results we propose a mechanism by which [CO3 2−]ECF is influenced by [Ca2+]SW. This mechanism suggests that the pHECF will be lowest in our highest [Ca2+] treatment and using this relationship we can place constraints on the pHECF. The difference in pHECF in our treatments is supported in part by a slight, but insignificant decrease in skeletal δ11B and δ13C values. We propose a novel dual-proxy approach to estimate pHECF, where calcification occurs at a pHECF > 9. This work emphasizes the importance of multi-element proxy approaches in understanding pH up-regulation and CO3 2− concentrations during calcification of corals.
AB - In order to better understand the response of coral calcification to changes in seawater chemistry, fragments of the coral Pocillopora damicornis were grown in seawater with varying [Ca2+]. Using a combined trace element (B/Ca) and stable isotope (δ11B, δ13C) approach, this paper explores the effect of seawater calcium concentrations ([Ca2+]SW) on coral calcification mechanisms and describes the manipulation of the extracellular calcifying fluid (ECF) pH (pHECF), saturation state (ΩECF) and dissolved inorganic carbon (DIC) speciation of the ECF. In these experiments, increases in [Ca2+]SW did not significantly influence calcification rates but caused the skeletal B/Ca ratio to significantly increase. To explain these results we propose a mechanism by which [CO3 2−]ECF is influenced by [Ca2+]SW. This mechanism suggests that the pHECF will be lowest in our highest [Ca2+] treatment and using this relationship we can place constraints on the pHECF. The difference in pHECF in our treatments is supported in part by a slight, but insignificant decrease in skeletal δ11B and δ13C values. We propose a novel dual-proxy approach to estimate pHECF, where calcification occurs at a pHECF > 9. This work emphasizes the importance of multi-element proxy approaches in understanding pH up-regulation and CO3 2− concentrations during calcification of corals.
KW - boron
KW - carbon isotopes
KW - dissolved inorganic carbon
KW - pH proxy
KW - seawater chemistry
UR - http://www.scopus.com/inward/record.url?scp=85065926772&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85065926772&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2019.05.008
DO - 10.1016/j.epsl.2019.05.008
M3 - Article
AN - SCOPUS:85065926772
VL - 519
SP - 130
EP - 140
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
ER -