10.5061/DRYAD.BCC2FQZC7
Phelps, Samuel
0000-0002-9784-2305
Harvard University
Hennon, Gwenn
University of Alaska Fairbanks
Dyhrman, Sonya
Lamont-Doherty Earth Observatory
Hernández-Limón, María
0000-0001-7512-6562
University of Chicago
Williamson, Olivia
University of Miami
Polissar, Pratigya
University of California, Santa Cruz
Dataset S1 - Noelaerhabdaceae organic carbon isotope culture data compilation
Dryad
dataset
2021
FOS: Earth and related environmental sciences
alkenone
carbon isotope analysis
carbon isotopes
paleoclimate proxy
algal culture
Gephyrocapsa oceanica
Coccolithophore
pCO2
National Science Foundation
https://ror.org/021nxhr62
DGE16-44869
National Science Foundation
https://ror.org/021nxhr62
OCE1314336
Center for Climate and Life at Columbia University*
Lamont Climate Center*
G. Unger Vetlesen Foundation
https://ror.org/02j9g7j58
WSL Pure in partnership with Columbia University's Center for
Climate and Life*
Paul M. Angell Family Foundation
https://ror.org/05e276m57
Columbia University
https://ror.org/00hj8s172
Columbia University Bridge to PhD Program*
Center for Climate and Life at Columbia University
Lamont Climate Center
Columbia University Bridge to PhD Program
2021-07-02T00:00:00Z
2021-07-02T00:00:00Z
en
67678 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
The carbon isotope fractionation in algal organic matter (Ep), including
the long-chain alkenones produced by the coccolithophorid family
Noelaerhabdaceae, is used to reconstruct past atmospheric CO2 levels. The
conventional proxy linearly relates Ep to changes in cellular carbon
demand relative to diffusive CO2 supply, with larger Ep values occurring
at lower carbon demand relative to supply (i.e. abundant CO2). However,
the response of Gephyrocapsa oceanica, one of the dominant alkenone
producers of the last few million years, has not been studied closely.
Here we subject G. oceanica to various CO2 levels by increasing pCO2 in
the culture headspace, as opposed to increasing dissolved inorganic carbon
(DIC) and alkalinity concentrations at constant pH. We note no substantial
change in physiology, but observe an increase in Ep as carbon demand
relative to supply decreases, consistent with DIC manipulations. We
compile existing Noelaerhabdaceae Ep data and show that the diffusive
model poorly describes the data. A meta-analysis of individual treatments
(unique combinations of lab, strain, and light conditions) shows that the
slope of the Ep response depends on the light conditions and range of
carbon demand relative to CO2 supply in the treatment, which is
incompatible with the diffusive model. We model Ep as a multilinear
function of key physiological and environmental variables and find that
both photoperiod duration and light intensity are critical parameters, in
addition to CO2 and cell size. While alkenone carbon isotope ratios indeed
record CO2 information, irradiance and other factors are also necessary to
properly describe alkenone Ep.
G. oceanica RCC1303 was cultivated in triplicate batch culture at five
different pCO2 levels. CO2 modification was achieved by continuously
aerating the headspace of the culture flask. Alkenones were extracted
using accelerated solvent extraction and carbon isotope ratios were
measured by GC-IRMS. CO2 concentrations were calculated from measurements
of pH, total alkalinity, temperature, and salinity. Cell sizes were
measured by flow cytometry. Existing data were compiled from the
literature. Cell sizes and carbon content were standardized to the middle
of the photoperiod, where applicable.
Missing values are noted with “NaN.” Data sources are listed in the
references and explanatory columns (e.g. “Source of cell radius data”).
Information in columns titled “Note on XYZ” (e.g. “Note on d13C_POC
uncertainty”) reflect the source of information in the original
publication.