Calcium isotopes in scleractinian fossil corals since the Mesozoic

Implications for vital effects and biomineralization through time

Anne M. Gothmann, Michael L. Bender, Clara L. Blättler, Peter K Swart, Sharmila J. Giri, Jess F. Adkins, Jarosław Stolarski, John A. Higgins

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We present a Cenozoic record of δ44/40Ca from well preserved scleractinian fossil corals, as well as fossil coral δ44/40Ca data from two time periods during the Mesozoic (84 and 160 Ma). To complement the coral data, we also extend existing bulk pelagic carbonate records back to ~80 Ma. The same fossil corals used for this study were previously shown to be excellently preserved, and to be faithful archives of past seawater Mg/Ca and Sr/Ca since ~200 Ma (Gothmann et al., 2015). We find that the δ44/40Ca compositions of bulk pelagic carbonates from ODP Site 807 (Ontong Java Plateau) and DSDP Site 516 (Rio Grande Rise) have not varied by more than ~±0.20‰ over the last ~80 Myr. In contrast, the δ44/40Ca compositions of Mesozoic and Early Cenozoic fossil corals are ~1‰ lighter than those of modern corals.The observed change in coral δ44/40Ca does not likely reflect secular variations in seawater δ44/40Ca. Instead, we propose that it reflects a vital effect of calcification - specifically, a sensitivity of coral Ca isotope discrimination to changing seawater [Ca] and/or pH. Support for this hypothesis comes from the presence of an empirical correlation between our coral δ44/40Ca record and records of seawater [Ca] and pH since the Mesozoic (Lowenstein et al., 2003; Hönisch et al., 2012). We explore various mechanisms that could give rise to such a vital effect, including: (1) changes in calcification rate, (2) changes in proton pumping in exchange for Ca2+, (3) variable Rayleigh distillation from an isolated calcifying fluid, and (4) changes in the calcium mass balance of the extracellular calcifying fluid (termed here the "leaky Ca model"). We test for the dependence of seawater δ44/40Ca on external seawater [Ca] by measuring the δ44/40Ca of cultured corals grown in seawater solutions with [Ca] ranging from 10 to 15 mmol/kg. Corals grown under elevated [Ca] conditions show a slight, ~0.15‰ depletion of δ44/40Ca at higher seawater [Ca] - a supportive but not definitive result.

Original languageEnglish (US)
Pages (from-to)205-214
Number of pages10
JournalEarth and Planetary Science Letters
Volume444
DOIs
StatePublished - Jun 15 2016

Fingerprint

Calcium Isotopes
calcium isotopes
Biomineralization
biomineralization
fossils
Seawater
coral
calcium
isotope
fossil
calcification
seawater
carbonates
Rio Grande (North America)
secular variations
distillation
fluids
mass balance
Carbonates
complement

Keywords

  • Bulk carbonate
  • Ca isotopes
  • Culture experiment
  • Scleractinian coral
  • Seawater chemistry
  • Vital effects

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Calcium isotopes in scleractinian fossil corals since the Mesozoic : Implications for vital effects and biomineralization through time. / Gothmann, Anne M.; Bender, Michael L.; Blättler, Clara L.; Swart, Peter K; Giri, Sharmila J.; Adkins, Jess F.; Stolarski, Jarosław; Higgins, John A.

In: Earth and Planetary Science Letters, Vol. 444, 15.06.2016, p. 205-214.

Research output: Contribution to journalArticle

Gothmann, Anne M. ; Bender, Michael L. ; Blättler, Clara L. ; Swart, Peter K ; Giri, Sharmila J. ; Adkins, Jess F. ; Stolarski, Jarosław ; Higgins, John A. / Calcium isotopes in scleractinian fossil corals since the Mesozoic : Implications for vital effects and biomineralization through time. In: Earth and Planetary Science Letters. 2016 ; Vol. 444. pp. 205-214.
@article{b8fa1a95f1b14eda8f83f40adb733146,
title = "Calcium isotopes in scleractinian fossil corals since the Mesozoic: Implications for vital effects and biomineralization through time",
abstract = "We present a Cenozoic record of δ44/40Ca from well preserved scleractinian fossil corals, as well as fossil coral δ44/40Ca data from two time periods during the Mesozoic (84 and 160 Ma). To complement the coral data, we also extend existing bulk pelagic carbonate records back to ~80 Ma. The same fossil corals used for this study were previously shown to be excellently preserved, and to be faithful archives of past seawater Mg/Ca and Sr/Ca since ~200 Ma (Gothmann et al., 2015). We find that the δ44/40Ca compositions of bulk pelagic carbonates from ODP Site 807 (Ontong Java Plateau) and DSDP Site 516 (Rio Grande Rise) have not varied by more than ~±0.20‰ over the last ~80 Myr. In contrast, the δ44/40Ca compositions of Mesozoic and Early Cenozoic fossil corals are ~1‰ lighter than those of modern corals.The observed change in coral δ44/40Ca does not likely reflect secular variations in seawater δ44/40Ca. Instead, we propose that it reflects a vital effect of calcification - specifically, a sensitivity of coral Ca isotope discrimination to changing seawater [Ca] and/or pH. Support for this hypothesis comes from the presence of an empirical correlation between our coral δ44/40Ca record and records of seawater [Ca] and pH since the Mesozoic (Lowenstein et al., 2003; H{\"o}nisch et al., 2012). We explore various mechanisms that could give rise to such a vital effect, including: (1) changes in calcification rate, (2) changes in proton pumping in exchange for Ca2+, (3) variable Rayleigh distillation from an isolated calcifying fluid, and (4) changes in the calcium mass balance of the extracellular calcifying fluid (termed here the {"}leaky Ca model{"}). We test for the dependence of seawater δ44/40Ca on external seawater [Ca] by measuring the δ44/40Ca of cultured corals grown in seawater solutions with [Ca] ranging from 10 to 15 mmol/kg. Corals grown under elevated [Ca] conditions show a slight, ~0.15‰ depletion of δ44/40Ca at higher seawater [Ca] - a supportive but not definitive result.",
keywords = "Bulk carbonate, Ca isotopes, Culture experiment, Scleractinian coral, Seawater chemistry, Vital effects",
author = "Gothmann, {Anne M.} and Bender, {Michael L.} and Bl{\"a}ttler, {Clara L.} and Swart, {Peter K} and Giri, {Sharmila J.} and Adkins, {Jess F.} and Jarosław Stolarski and Higgins, {John A.}",
year = "2016",
month = "6",
day = "15",
doi = "10.1016/j.epsl.2016.03.012",
language = "English (US)",
volume = "444",
pages = "205--214",
journal = "Earth and Planetary Sciences Letters",
issn = "0012-821X",
publisher = "Elsevier",

}

TY - JOUR

T1 - Calcium isotopes in scleractinian fossil corals since the Mesozoic

T2 - Implications for vital effects and biomineralization through time

AU - Gothmann, Anne M.

AU - Bender, Michael L.

AU - Blättler, Clara L.

AU - Swart, Peter K

AU - Giri, Sharmila J.

AU - Adkins, Jess F.

AU - Stolarski, Jarosław

AU - Higgins, John A.

PY - 2016/6/15

Y1 - 2016/6/15

N2 - We present a Cenozoic record of δ44/40Ca from well preserved scleractinian fossil corals, as well as fossil coral δ44/40Ca data from two time periods during the Mesozoic (84 and 160 Ma). To complement the coral data, we also extend existing bulk pelagic carbonate records back to ~80 Ma. The same fossil corals used for this study were previously shown to be excellently preserved, and to be faithful archives of past seawater Mg/Ca and Sr/Ca since ~200 Ma (Gothmann et al., 2015). We find that the δ44/40Ca compositions of bulk pelagic carbonates from ODP Site 807 (Ontong Java Plateau) and DSDP Site 516 (Rio Grande Rise) have not varied by more than ~±0.20‰ over the last ~80 Myr. In contrast, the δ44/40Ca compositions of Mesozoic and Early Cenozoic fossil corals are ~1‰ lighter than those of modern corals.The observed change in coral δ44/40Ca does not likely reflect secular variations in seawater δ44/40Ca. Instead, we propose that it reflects a vital effect of calcification - specifically, a sensitivity of coral Ca isotope discrimination to changing seawater [Ca] and/or pH. Support for this hypothesis comes from the presence of an empirical correlation between our coral δ44/40Ca record and records of seawater [Ca] and pH since the Mesozoic (Lowenstein et al., 2003; Hönisch et al., 2012). We explore various mechanisms that could give rise to such a vital effect, including: (1) changes in calcification rate, (2) changes in proton pumping in exchange for Ca2+, (3) variable Rayleigh distillation from an isolated calcifying fluid, and (4) changes in the calcium mass balance of the extracellular calcifying fluid (termed here the "leaky Ca model"). We test for the dependence of seawater δ44/40Ca on external seawater [Ca] by measuring the δ44/40Ca of cultured corals grown in seawater solutions with [Ca] ranging from 10 to 15 mmol/kg. Corals grown under elevated [Ca] conditions show a slight, ~0.15‰ depletion of δ44/40Ca at higher seawater [Ca] - a supportive but not definitive result.

AB - We present a Cenozoic record of δ44/40Ca from well preserved scleractinian fossil corals, as well as fossil coral δ44/40Ca data from two time periods during the Mesozoic (84 and 160 Ma). To complement the coral data, we also extend existing bulk pelagic carbonate records back to ~80 Ma. The same fossil corals used for this study were previously shown to be excellently preserved, and to be faithful archives of past seawater Mg/Ca and Sr/Ca since ~200 Ma (Gothmann et al., 2015). We find that the δ44/40Ca compositions of bulk pelagic carbonates from ODP Site 807 (Ontong Java Plateau) and DSDP Site 516 (Rio Grande Rise) have not varied by more than ~±0.20‰ over the last ~80 Myr. In contrast, the δ44/40Ca compositions of Mesozoic and Early Cenozoic fossil corals are ~1‰ lighter than those of modern corals.The observed change in coral δ44/40Ca does not likely reflect secular variations in seawater δ44/40Ca. Instead, we propose that it reflects a vital effect of calcification - specifically, a sensitivity of coral Ca isotope discrimination to changing seawater [Ca] and/or pH. Support for this hypothesis comes from the presence of an empirical correlation between our coral δ44/40Ca record and records of seawater [Ca] and pH since the Mesozoic (Lowenstein et al., 2003; Hönisch et al., 2012). We explore various mechanisms that could give rise to such a vital effect, including: (1) changes in calcification rate, (2) changes in proton pumping in exchange for Ca2+, (3) variable Rayleigh distillation from an isolated calcifying fluid, and (4) changes in the calcium mass balance of the extracellular calcifying fluid (termed here the "leaky Ca model"). We test for the dependence of seawater δ44/40Ca on external seawater [Ca] by measuring the δ44/40Ca of cultured corals grown in seawater solutions with [Ca] ranging from 10 to 15 mmol/kg. Corals grown under elevated [Ca] conditions show a slight, ~0.15‰ depletion of δ44/40Ca at higher seawater [Ca] - a supportive but not definitive result.

KW - Bulk carbonate

KW - Ca isotopes

KW - Culture experiment

KW - Scleractinian coral

KW - Seawater chemistry

KW - Vital effects

UR - http://www.scopus.com/inward/record.url?scp=84962628052&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84962628052&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2016.03.012

DO - 10.1016/j.epsl.2016.03.012

M3 - Article

VL - 444

SP - 205

EP - 214

JO - Earth and Planetary Sciences Letters

JF - Earth and Planetary Sciences Letters

SN - 0012-821X

ER -