Deep oxygen-depleted Red Sea coral reef depressions sustain resistant ecosystems

Persistent oxygen-depleted zones in the ocean are known primarily from enclosed basins in temperate regions or the open-ocean (including oxygen minimum and limiting zones). However, little is known about the potential for such zones in tropical coastal domains, despite warmer temperatures and complex geomorphological structures in some tropical areas increasing the likelihood of their existence. Here, we report two subsurface oxygen-depleted zones within deep depressions of the Red Sea’s Difaht Farasan—a carbonate platform hosting the world’s third-largest contiguous tropical coral reef system. One zone maintains suboxic oxygen levels (~11-14 µmol kg⁻¹), while the other sustains oxygen levels below detection (<2 µmol kg⁻¹). The suboxic zone shows no fixed nitrogen loss, while the near-anoxic zone hosts anaerobic microbial populations and shows signs of nitrogen loss. We propose that the warm and saline environment of the Red Sea interacts with the semi-enclosed depressions to restric..., , , # Data from: Deep oxygen-depleted Red Sea coral reef depressions sustain resistant ecosystems

(Published in PNAS Nexus)

**Authors:** Shannon G. Klein, Larissa Frühe, Anieka J. Parry, Fabio Marchese, Megan K. B. Nolan, Elisa Laiolo, Kah Kheng Lim, Alexandra Steckbauer, Jessica Breavington, Christopher A. Hempel, Kate von Krusenstiern, Froukje M. van der Zwan, Eleonora Re, Taiba Alamoudi, Jacqueline V. Alva Garcia, Silvia Arossa, Carlos A. Preckler, Mattie Rodrigue, Vincent A. Pieribone, Mohammad A. Qurban, Francesca Benzoni, and Carlos M. Duarte

Correspondence: Shannon G. Klein; [[e-mail]](mailto:[e-mail])

The associated dryad repository contains ten files:

## Supplementary Data File 1

This file contains 5 columns and is the source data file for Figure 2(a-c) of the associated publication. Data represent the full depth profiles of dissolved oxygen, temperature, and salinity within two deep depressions of the Farasan Bank, Saudi Arabia (sites 1 a...