DOI: 10.5061/dryad.41ns1rnj7
title: Data for: Increasing hypoxia on global coral reefs under ocean warming

description: Ocean deoxygenation is predicted to threaten marine ecosystems globally.
 However, current and future oxygen concentrations and the occurrence of
 hypoxic events on coral reefs remain underexplored. Here, using autonomous
 sensor data to explore oxygen variability and hypoxia exposure at 32
 representative reef sites, we reveal that hypoxia is already pervasive on
 many reefs. 84% of reefs experienced weak to moderate (≤153 to ≤92 μmol O2
 kg-1) hypoxia and 13% experienced severe (≤61 μmol O2 kg-1) hypoxia. Under
 different climate change scenarios based on 4 Shared Socioeconomic
 Pathways (SSPs), we show that projected ocean warming and deoxygenation
 will increase the duration, intensity, and severity of hypoxia, with more
 than 94% and 31% of reefs experiencing weak to moderate and severe
 hypoxia, respectively, by 2100 under SSP5-8.5. This projected oxygen loss
 could have negative consequences for coral reef taxa due to the key role
 of oxygen in organism functioning and fitness.
description: As described in the Methods
 section of the accompanying manuscript and the Supplementary Information
 by Pezner et al.:<br>
 <strong>Sensor and
 deployment information</strong>
 The majority of dissolved oxygen
 data presented in the current study (25 of 32 sites) were recorded by
 SeapHOx or Sea-Bird Scientific CTD sensor packages with Aanderaa oxygen
 optodes (Table S1). The remaining oxygen datasets were recorded by
 Idronaut CTD and oxygen sensor packages (Dongsha 1 and Dongsha 2),
 Sea-Bird SBE19 Plus CTD and SBE 43 oxygen sensor packages (Baker, Jarvis,
 Palmyra 3, and Tutuila), or Sea-Bird Scientific CTD and PME miniDOT sensor
 packages (Taiping 1). Detailed site and deployment information can be
 found in the Supplementary Information Extended Methods section. For each
 location, different instrument deployment sites are represented by numbers
 (e.g., Dongsha 1 and Dongsha 2), or a combination of letters and numbers
 where letters represent either different depths at the same site (e.g.,
 Bocas 1a, 1b, 1c, and 1d) or different deployments at the same site over
 time (e.g., Crocker 1a, 1b, and 1c). 
 <strong>Calibrations and
 conversions of datasets</strong>
 All sensors were calibrated by
 the manufacturer or according to the manufacturer’s instructions by the
 user as noted in previous publications. If applicable, salinity
 corrections were implemented according to the manufacturer’s
 specifications and analog measurements were converted from voltages to
 concentrations. Data were assessed for quality and erroneous data points
 (defined as missing values or values that exceeded the measurement range
 of the instrument), which were flagged and excluded from any subsequent
 analyses. Deployment data were restricted to measurements in seawater
 based on salinity values to exclude extraneous data points collected
 during instrument transport, initial deployment, or recovery (exposure to
 air). Density calculations using the Gibbs Seawater Toolbox functions in
 RStudio were used to convert all oxygen concentration units to μmol
 O<sub>2</sub> kg<sup>-1</sup>. See Supplementary
 Information Extended Methods (and Table S8) for an assessment and
 discussion on the potential errors and uncertainty of the oxygen
 measurements. All data and relevant code (https://github.com/apezner/GlobalReefOxygen) files are available for download online and may be used with proper attribution.
description: The primary dataset is provided as an R data file and in CSV
 format for ease of access. All secondary datasets are provided in CSV
 format.