Year: 2026
Type: preprint
Abstract: Marine heatwaves cause massive, but often patchy coral bleaching. Why neighboring colonies often respond differently remains unresolved. Here, we show that interactions between metabolic demand and flow-mediated resupply generate heterogeneous oxygen microenvironments inside branching corals under heat stress. During the 2023 and 2024 Red Sea heatwaves, high-frequency in situ measurements revealed hypoxic to near-anoxic interbranch conditions despite well-oxygenated surrounding seawater. In 2023, neighboring colonies developed divergent oxygen regimes preceding paling and bleaching; in 2024, stronger and earlier thermal stress was associated with recurrent nighttime near-anoxia before tissue disintegration and mortality. A physics-based three-dimensional fluid-metabolism model reproduced these patterns. Oxygen depletion and coral impacts emerged when metabolic oxygen demand exceeded flow-mediated resupply. Organism-scale variability in oxygen regimes may explain divergent coral fate under shared heatwave exposure.
Authors: Yusuf C. El-Khaled, Hamid H. Khan, Shannon G. Klein, Neus Garcias-Bonet, Dilip Maity, Sandip Dighe, Timofey Mukha, Abhijit K. Kushwaha, Fauzia Wardani, Mourad Oulghelou, Max S. Dhillon, Spencer Truman, Francisca C. García, Maggie D. Johnson, Michael Fox, Carlos M. Duarte, Susana Carvalho, David J. Suggett, Raquel S. Peixoto, Matteo Parsani, Tadd T. Truscott
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life below water
Open Access status: green
Awards: G3005148742, G751284401
OpenAlex ID: W7221088858