A recent review article by NCCOS-supported researchers assessing the state of knowledge of hypoxia (low oxygen) in tropical ecosystems finds little information in comparison to what is known about hypoxia in temperate and sub-tropical ecosystems. Yet, coral reefs, mangroves, and seagrass meadows regularly experience hypoxia, sometimes daily. How these ecosystems remain resilient to hypoxia could help us identify how organisms may be impacted or adapt to hypoxia in more temperate ecosystems.

Diver servicing sensors to measure water quality parameters including dissolved oxygen, temperature, salinity, pH and light at a coral restoration site in the Florida Keys. Photo Credit: Emily Nixon.

Although some tropical organisms are well adapted to living in hypoxic conditions, there is concern regarding how other stressors (such as increasing ocean temperatures, ocean acidification, and eutrophication) may increase the effects of hypoxia. To improve our understanding of the interaction of hypoxia with other ecosystem stressors in tropical ecosystems, the authors recommend including the measurement of dissolved oxygen in monitoring programs. They also suggest ecological studies to understand how large habitat-forming organisms, such as corals, seagrasses, and mangroves modify those stressors.

This project is part of the NCCOS Coastal Hypoxia Research Program, and is led by the University of Florida in collaboration with the Smithsonian Institution. It is examining the impact of hypoxia on coral reef ecosystems.

Citation: Altieri, A. H., M. D. Johnson, S. D. Swaminathan, H. R. Nelson and K. B. Gedan. 2021. Resilience of tropical ecosystems to oxygen deoxygenation. Trends in Ecology and Evolution 36(3): 227-238. https://doi.org/10.1016/j.tree.2020.11.003