Oxygen isotope variability of planktonic foraminifera provide clues to past upper ocean seasonal variability

Brett Metcalfe*, Wouter Feldmeijer, Gerald M. Ganssen

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


The major control upon abundance of planktonic foraminifera and their stable oxygen isotope (δ 18 O) signature is the seasonally linked variation in water hydrography, key to the proliferation or attenuation of ecologically beneficial constraints. The range and variance σ(δ 18 O) of planktonic foraminifera can reflect changes in either the season or depth of calcification. For a detailed reconstruction of ocean changes we employed multispecies single-specimen analysis, which allows extraction of the isotopic variability within the species for the time covered by the sample. Previous studies with pooled specimens have shown that the multiannual temperature range may be extracted. Here we investigate how seasonality can be deduced from single-specimen analysis of planktonic foraminifera combined with multiple other proxies (IRD percent, faunal abundance) from Termination III. Our single-shell isotope results show that the variance in Globigerina bulloides oxygen isotope values corresponds to the insolation at the core site. Furthermore, faunal and isotopic analyses of the polar-subpolar neogloboquadrinid species, N. pachyderma (NPS) and N. incompta, reveal an intriguing result. These species are sister taxa, representing genetically distinct species, whose relative abundance reflects warm and cold conditions. While the difference between their isotopic means should reflect the temperature difference between their distinct growing seasons, we show that this difference also has a statistically significant relationship with the spread in individual NPS δ 18 O. At an appropriate core site, this approach could be used to further constrain the length of the growing season and therefore the inherent variability recorded within proxy records.

Original languageEnglish
Pages (from-to)374-393
Number of pages20
JournalPaleoceanography and Paleoclimatology
Issue number3
Early online date8 Feb 2019
Publication statusPublished - Mar 2019


This work is part of the research program “Digging for Density” with project NWO/822.01.0.19, which is financed by the Netherlands Organization for Scientific Research (NWO). The authors acknowledge the Darwin Center for Biogeosciences Theme 2 project “Sensing Seasonality” with project 3043, which partially funded this project, and the European 7th Framework Project European Project for Ocean Acidification (EPOCA; FP7/211384). B.M. is sup ported by a Laboratoire d'Excellence (LabEx) award from the Institut Pierre‐ Simon Laplace (IPSL). Data are avail able in Table 1.

FundersFunder number
European 7th Framework Project European Project for Ocean AcidificationFP7/211384
Netherlands Organization for Scientific Research
Seventh Framework Programme211384
Darwin College, University of Cambridge


    • individual foraminiferal analysis
    • planktonic foraminifera
    • seasonality
    • single-shell analysis
    • stable isotopes
    • Termination III


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