DOI: 10.5061/dryad.x95x69ptd
title: Decadal oscillations in the ocean's largest oxygen-deficient zone - coral isotopes records & linear extension rates

description: The impact of global warming on the ocean’s oxygen-deficient zones (ODZs)
 is poorly known, in part due to a lack of data on past changes. We present
 monthly resolved records of coral skeleton-bound nitrogen isotopes
 (CS-δ15N) to reconstruct denitrification in the ODZ of the Eastern
 Tropical North Pacific (ETNP) over the last 80 years. The data record
 strong decadal variation in ETNP denitrification in phase with the Pacific
 Decadal Variability (PDV). Denitrification (and thus oxygen deficiency) is
 enhanced in the cold PDV phase, likely due to stronger upwelling, enhanced
 productivity, and thus greater oxygen demand in the thermocline. Prior
 findings of ODZ expansion were likely biased by this variability.
 ODZ's evolution in the next century will depend on how global warming
 influences these decadal changes.
description: # Decadal oscillations in the ocean's largest oxygen-deficient zone -
 coral isotopes records & linear extension rates
 [https://doi.org/10.5061/dryad.x95x69ptd](https://doi.org/10.5061/dryad.x95x69ptd) ## Description of the data and file structure ### Files and variables #### File: Duprey\_et\_al\_adk4965\_data.xls | **Field** | **Description** | | :--------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | *ID* | ID tag of the coral core. \[CORE NAME]-\[SECTION NUMBER]-\[SAMPLE NUMBER] - section number: smallest number is most recent - sample number: samples a collected downcore, from the top of each section (#001). Details about the cores can be found in Table S1. | | *Date* | Date attributed from an age model built on growth bands count and/or δ18O seasonal cycles | | *δ15N‰air* | Stable nitrogen isotope ratio from the aragonite-bound organic matrix after bleach-cleaning. Analytical method from: - Wang, X. T., Sigman, D. M., Cohen, A. L., Sinclair, D. J., Sherrell, R. M., Weigand, M. A., Erler, D. V., & Ren, H. (2015). Isotopic composition of skeleton-bound organic nitrogen in reef-building symbiotic corals: A new method and proxy evaluation at Bermuda. Geochimica et Cosmochimica Acta, 148, 179–190. - Martínez-García, A., Jung, J., Ai, X. E., Sigman, D. M., Auderset, A., Duprey, N. N., Foreman, A., Fripiat, F., Leichliter, J., Lüdecke, T., Moretti, S., & Wald, T. (2022). Laboratory assessment of the impact of chemical oxidation, mineral dissolution, and heating on the nitrogen isotopic composition of fossil‐bound organic matter. Geochemistry, Geophysics, Geosystems, 23(8), 1–23. Missing values are noted as “nan”  | | *N-content (nmolN/ mgCaCO3)* | Amount of organic N per weight unit of bleached-cleaned coral skeleton powder. Missing values are noted as “nan” | | *δ18O(‰vpdb)* | Stable oxygen isotope ratio from the inorganic phase of the coral skeleton (i.e., aragonite). Analytical method from: - Vonhof, H. B., de Graaf, S., Spero, H. J., Schiebel, R., Verdegaal, S. J. A., Metcalfe, B., & Haug, G. H. (2020). High-precision stable isotope analysis of &lt;5 μg CaCO3 samples by continuous-flow mass spectrometry. Rapid Communications in Mass Spectrometry: RCM, 34(19), e8878. Missing values are noted as “nan” | | *sd* | standard deviation (1SD) corresponding to the mean value of the variable located on the left of the sd column. Missing values are noted as “nan” | | *n* | number of of values averaged in the calculation of the sd. When only 1 replicate is available sd = nan. | | *year* | calendar corresponding to the linear extension rate time series. Missing values are noted as “nan” | | *\[CORE ID]\_LER (mm/y)* | yearly linear extension rate based on either the density bands or the distance between the winter value of the δ18O seasonal cycles. Missing values are noted as “nan” |