Marine Heatwave and Extreme Hypoxia Coincide With Rapid Coral Bleaching and Mortality on a Central Red Sea Coral Reef
- 1Marine Science Program, Biological and Environmental Science and Engineering Division (BESE) King Abdullah University of Science and Technology (KAUST) Thuwal Kingdom of Saudi Arabia
Abstract
Coral bleaching and mortality are commonly associated with heat stress during marine heatwaves (MHWs), yet attributing these responses solely to heat stress may overlook the complexity of contemporary MHWs. Here, we document a severe MHW affecting a central Red Sea reef in mid‐2024 that coincided with repeated nighttime low‐oxygen events. By integrating satellite and in situ records of temperature, dissolved oxygen and wind, alongside repeated surveys of in situ nursery‐reared coral fragments, we document the temporal coincidence of these conditions with rapid coral bleaching and mortality. As temperatures approached and exceeded 33°C during the MHW peak, nighttime oxygen minima were extreme (down to 15.2–57.8 μmol O ₂ kg ⁻¹ ) and diel temperature variability diminished (down to 0.31°C–0.67°C), indicating a loss of nighttime thermal reprieves. Coincident responses of nursery corals were atypical, with transitions from healthy or bleached states to mortality occurring within 7–8 days. Bleaching and mortality also occurred across diverse coral species in nearby habitats after the MHW peak, with < 1% live coral cover documented eight months later. Sustained high temperatures, reduced vertical mixing and increased nighttime respiratory demand likely constrained oxygen availability, resulting in low‐oxygen extremes. We posit that similar compound MHW extreme events may have gone undetected in the Red Sea and elsewhere, potentially obscuring the contribution of co‐occurring low‐oxygen extremes to coral responses attributed to heat stress.
Related
- Delayed bleaching-induced coral mortality limits reef recovery after a marine heatwave
- Genomic changes revealed by repeated sampling of kelp exposed to an extreme marine heatwave
- Awake sharp-wave ripples coincide with rhythmic cortical synchronization
- Rapid coral bleaching recovery via symbiont transfer from healthy corals
- Diel thermal variability does little to mitigate bleaching in two endangered coral holobionts
BibTeX
@article{klein2026marine,
title = {{Marine Heatwave and Extreme Hypoxia Coincide With Rapid Coral Bleaching and Mortality on a Central Red Sea Coral Reef}},
author = {Shannon G. Klein and Eleonora Re and Naira Pluma and Cassandra Roch and Carlos M. Duarte},
journal = {Ecology and Evolution},
year = {2026},
month = nov,
doi = {10.1002/ece3.74606},
url = {https://onlinelibrary.wiley.com/doi/10.1002/ece3.74606},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Marine Heatwave and Extreme Hypoxia Coincide With Rapid Coral Bleaching and Mortality on a Central Red Sea Coral Reef
AU - Shannon G. Klein
AU - Eleonora Re
AU - Naira Pluma
AU - Cassandra Roch
AU - Carlos M. Duarte
PY - 2026
DA - 2026/11/04
JO - Ecology and Evolution
DO - 10.1002/ece3.74606
UR - https://onlinelibrary.wiley.com/doi/10.1002/ece3.74606
AB - Coral bleaching and mortality are commonly associated with heat stress during marine heatwaves (MHWs), yet attributing these responses solely to heat stress may overlook the complexity of contemporary MHWs. Here, we document a severe MHW affecting a central Red Sea reef in mid‐2024 that coincided with repeated nighttime low‐oxygen events. By integrating satellite and in situ records of temperature, dissolved oxygen and wind, alongside repeated surveys of in situ nursery‐reared coral fragments, we document the temporal coincidence of these conditions with rapid coral bleaching and mortality. As temperatures approached and exceeded 33°C during the MHW peak, nighttime oxygen minima were extreme (down to 15.2–57.8 μmol O ₂ kg ⁻¹ ) and diel temperature variability diminished (down to 0.31°C–0.67°C), indicating a loss of nighttime thermal reprieves. Coincident responses of nursery corals were atypical, with transitions from healthy or bleached states to mortality occurring within 7–8 days. Bleaching and mortality also occurred across diverse coral species in nearby habitats after the MHW peak, with < 1% live coral cover documented eight months later. Sustained high temperatures, reduced vertical mixing and increased nighttime respiratory demand likely constrained oxygen availability, resulting in low‐oxygen extremes. We posit that similar compound MHW extreme events may have gone undetected in the Red Sea and elsewhere, potentially obscuring the contribution of co‐occurring low‐oxygen extremes to coral responses attributed to heat stress.
SN - 2045-7758
SN - 2045-7758
ER -