Earth Institute Research Projects

Testing geochemical proxy relationships under variable paleo-seawater chemical compositions

Lead PI: Dr. Baerbel Hoenisch

Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)

September 2012 - August 2017
Global ; Catalina Island, CA ; Isla Magueyes, Puerto Rico
Project Type: Research

DESCRIPTION: This project funded culture experiments to study the effect of Paleocene seawater composition on the B/Ca ratio and photosynthetic activity in planktic foraminifers.

OUTCOMES: B/Ca increases with boron concentration in seawater in G. sacculifer, G. ruber, and O. universa. None of these species show a measurable B/Ca response to varying calcium concentrations, which suggests that in contrast to inorganic precipitation studies, modifications to calcite growth rate do not significantly affect B/Ca in foraminifera. Paleocene experiments in G. sacculifer and O. universa have additionally confirmed the DIC effect on B/Ca, and we have created another set of calibrations for application to the PETM records of Penman et al. (2014, Paleoceanography) from this species for the relative influence of pH and DIC changes. In addition, geochemical proxies are often used to infer growth habitats and vital effects in planktic foraminifers. As such, it has been interpreted from B/Ca and boron isotopes that G. ruber inhabits a shallower growth habitat than G. sacculifer and O. universa, and/or that its symbionts are more active than in G. sacculifer and O. universa. Our FRRF data show that all three species have similar fluorescence, and Chlorophyll a concentrations and symbiont counts are comparable between all three species, which suggests that we need to consider other parameters, e.g. gametogenic calcite precipitation in G. sacculifer and O. universa or differential boron discrimination in different foraminifer species, to cause the observed geochemical offsets.


National Science Foundation (NSF)




Laura Haynes, Carina Fish


Australian National University, Rutgers University New Brunswick



Branson, O., E. Bonnin, D. Perea, H.J. Spero, Z. Zhu, M. Winters, B. Hönisch, A. Russell, J. Fehrenbacher, A.C. Gagnon, “Nanometer-Scale Chemistry of a Calcite Biomineralization Template: Implications for Skeletal Composition and Nucleation”, Proceedings of the National Academy of Sciences 113, p. 12934-12939m, doi: 10.1073/pnas.1522864113.

Spero, H.J., S.M. Eggins, A.D. Russell, L. Vetter, M.R. Kilburn, B. Hönisch, “Timing and Mechanism for intratest Mg/Ca variability in living planktic foraminifera”, Earth and Planetary Science Letters 409, doi: 10.1016/j.epsl.2014.10.030.

L.L. Haynes, B. Hönisch, §K. Dyez, K. Holland, Y. Rosenthal, *C. Fish, A. Subhas, J. Rae, “Calibration of the B/Ca proxy in the planktic foraminifer Orbulina universa to Paleocene seawater conditions”, Paleoceanography, Volume 32, Issue 6, P. 580-599, doi: 10.1002/2016PA003069.

K. Holland, S. Eggins, B. Hönisch, *L. Haynes, “Calcification rate and shell chemistry response of the planktic foraminifer Orbulina universa to changes in microenvironment seawater carbonate chemistry”, Earth and Planetary Science Letters, Volume 464, Pages 124-134.

Fehrenbacher, J.S., Russell, A.D., Davis, C.V., Spero, H.J., Chu, E. and Hönisch, B. (2018) Ba/Ca ratios in the non-spinose planktic foraminifer Neogloboquadrina dutertrei: Evidence for an organic aggregate microhabitat. Geochimica et Cosmochimica Acta 236, 361-372.

Hönisch, B., S.M. Eggins, *L.L. Haynes, K.A. Allen, K. Holland, K. Lorbacher, “Boron proxies in Paleoceanography and Paleoclimatology” in Analytical Methods in Earth and Environmental Science, 264 pp., First Edition, John Wiley & Sons Ltd., 2019.

Bonnin, E.A., Z. Zhu, J.S. Fehrenbacher, A.D. Russell, B. Hönisch, H.J. Spero, A.C. Gagnon, “Submicron Sodium Banding in Planktic Foraminifera Shells”, Geochimica at Cosmochimica Acta 253, p. 127-141.

Two more manuscripts are submitted: *Haynes, L., B. Hönisch, K. Holland, Y. Rosenthal, S.M. Eggins, “Development of the B/Ca proxy in planktic foraminifera for quantitative application to Paleogene ocean acidification events”, submitted to Earth and Planetary Science Letters.

Holland, K., O. Branson, *L.L. Haynes, B. Hönisch, K. Allen, A.D.R. Russell, J. Fehrenbacher, H.J. Spero, S.M. Eggins, “Constraining multiple controls on planktic foraminiferal Mg/Ca”, submitted to Geochimica et Cosmochimica Acta.

Two additional manuscripts are in preparation: *Haynes, L., B. Hönisch, K. Holland, Y. Rosenthal, S.M. Eggins, “Influence of pH and Dissolved Inorganic Carbon on Planktic Foraminiferal Mg/Ca in low Mg/Casw”, in prep.

Hönisch, B., *C. Fish, S. Phelps, *L.L. Haynes, §K. Dyez, K. Holland, S.M. Eggins, J. Fehrenbacher, and J.I. Goes, “Unraveling Vital Effects: Photosynthesis of Symbiotic Algae in Foraminifera Hosts”, in prep.


ocean and climate physics boron paleooceanographic reconstructions marine carbonates calcium (ca) planktic foraminifers


Modeling and Adapting to Future Climate