The influence of geochemical variation among Globigerinoides ruber individuals on paleoceanographic reconstructions
The influence of geochemical variation among Globigerinoides ruber individuals on paleoceanographic reconstructions
Variation among individuals within species is a biological precondition for co-existence. Traditional geochemical analysis based on bulk averages facilitates rapid data gathering but necessarily means the loss of large amounts of potentially crucial information into variability within a given sample. As the sensitivity of geochemical analysis improves, it is now feasible to build sufficiently powerful datasets to investigate paleoclimatic variation at the level of individual specimens. Here, we investigate geochemical and morphological variation among the sensu stricto, sensu lato and sensu lato extreme subspecies of the workhorse extant planktic foraminifera Globigerinoides ruber. Our experimental design distinguishes between subspecies and intraspecific variability as well as the repeatability of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We show that geochemical variability in Mg/Ca ratios is driven by differences in subspecies depth habitat and that ontogenetic trends in Mg/Ca ratios are evident in the final whorl, with the final chamber consistently showing depleted Mg/Ca. These ontogenetic trends are not driven by individual chamber or test size. The Mg/Ca value variance among individuals is ∼100 times higher than the variance among repeated laser spot analyses of single chambers, directing laboratory protocols towards the need to sample ecologically and environmentally homogeneous samples. Our results emphasize that we can use LA-ICP-MS to quantify how individual variability aggregates to bulk results, and highlights that, with sufficient sample sizes, it is possible to reveal how intraspecific variability alters geochemical inference.
Globigerinoides ruber, LA-ICP-MS, Mg/Ca, morphology, planktic foraminifera, stable isotopes
Kearns, L.E.
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Searle-Barnes, A.
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Foster, G.L.
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Milton, J.A.
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Standish, C.D.
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Ezard, T.H.G.
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1 April 2023
Kearns, L.E.
a90251d2-4814-474e-a400-ad9a112bd964
Searle-Barnes, A.
27cd9e5f-9a76-4d3d-8c88-0d3d0b1fad63
Foster, G.L.
fbaa7255-7267-4443-a55e-e2a791213022
Milton, J.A.
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Standish, C.D.
0b996271-da5d-4c4f-9e05-a2ec90e8561d
Ezard, T.H.G.
a143a893-07d0-4673-a2dd-cea2cd7e1374
Kearns, L.E., Searle-Barnes, A., Foster, G.L., Milton, J.A., Standish, C.D. and Ezard, T.H.G.
(2023)
The influence of geochemical variation among Globigerinoides ruber individuals on paleoceanographic reconstructions.
Paleoceanography and Paleoclimatology, 38 (4), [e2022PA004549].
(doi:10.1029/2022PA004549).
Abstract
Variation among individuals within species is a biological precondition for co-existence. Traditional geochemical analysis based on bulk averages facilitates rapid data gathering but necessarily means the loss of large amounts of potentially crucial information into variability within a given sample. As the sensitivity of geochemical analysis improves, it is now feasible to build sufficiently powerful datasets to investigate paleoclimatic variation at the level of individual specimens. Here, we investigate geochemical and morphological variation among the sensu stricto, sensu lato and sensu lato extreme subspecies of the workhorse extant planktic foraminifera Globigerinoides ruber. Our experimental design distinguishes between subspecies and intraspecific variability as well as the repeatability of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We show that geochemical variability in Mg/Ca ratios is driven by differences in subspecies depth habitat and that ontogenetic trends in Mg/Ca ratios are evident in the final whorl, with the final chamber consistently showing depleted Mg/Ca. These ontogenetic trends are not driven by individual chamber or test size. The Mg/Ca value variance among individuals is ∼100 times higher than the variance among repeated laser spot analyses of single chambers, directing laboratory protocols towards the need to sample ecologically and environmentally homogeneous samples. Our results emphasize that we can use LA-ICP-MS to quantify how individual variability aggregates to bulk results, and highlights that, with sufficient sample sizes, it is possible to reveal how intraspecific variability alters geochemical inference.
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Kearns23 - intraspecific ruber
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Paleoceanog and Paleoclimatol - 2023 - Kearns
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Accepted/In Press date: 6 March 2023
e-pub ahead of print date: 30 March 2023
Published date: 1 April 2023
Additional Information:
Funding Information:
This work was funded by the Natural Environment Research Council NE/P019269/1 to THGE. THGE was also funded by Fellowship NE/J018163/1; LEK was part‐funded by a University of Southampton Institute of Life Sciences' PhD Studentship and Natural Environment Research Council NE/L002531/1. We thank Ryan Glaubke and two anonymous reviewers for their comments on this manuscript, and three anonymous reviewers for their comments on a previous version of this manuscript. We also thank Dr Anieke Brombacher for helping with taxonomic and morphometric measurements and Dr Max Holmström helping with stable isotope measurements.
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© 2023. The Authors.
Keywords:
Globigerinoides ruber, LA-ICP-MS, Mg/Ca, morphology, planktic foraminifera, stable isotopes
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Local EPrints ID: 476728
URI: http://eprints.soton.ac.uk/id/eprint/476728
ISSN: 2572-4525
PURE UUID: 3cee015b-ba07-4822-8ecd-fe58e94eae5f
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Date deposited: 12 May 2023 16:47
Last modified: 22 Jun 2024 01:54
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T.H.G. Ezard
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