Reef-building corals at risk from ocean warming, acidification

Physiological limitations on regulating internal chemistry restricts corals’ ability to deal with ocean acidification and warming, thereby reducing resilience to continued environmental change.

Schematic of seawater and physiological controls for cold and warm seasons on calcifying fluid and skeletal geochemistry for 18th century fossil (pre-industrial) corals and modern corals. The reduction in active transport (red arrows, with thickness indicating relative magnitude) in modern corals, critical for regulating the geochemistry of the calcifying fluid, is enhanced by thermal stress such as occurs during El Niño conditions. Credit: Thompson et al., 2022, Figure 3

Environmental stress imposed by ocean warming and acidification has important implications for organism growth, especially those with carbonate skeletons, such as reef-building corals. Thompson et al. [2022] use coral geochemistry and results from Earth system modeling to examine the effects of these stressors on calcification and resiliency in Galápagos corals. Their analysis of calcifying fluid geochemistry in pre-industrial and modern corals suggests that there are physiological limits to coral buffering capacity that affect growth. The implication is that the capacity of corals to buffer against ocean acidification may be more limited than indicated by previous experimental studies. The reduced buffering capacity has consequences for calcification, which affects reef structure, function, and resilience, especially in marginal environments, such as the Galápagos.

Citation: Thompson, D., McCulloch, M., Cole, J., Reed, E., D’Olivo, J., Dyez, K., et al. [2022]. Marginal reefs under stress: physiological limits render Galapagos corals susceptible to ocean acidification and thermal stress. AGU Advances, 3, e2021AV000509. https://doi.org/10.1029/2021AV000509

Eileen Hofmann, AGU Advances (via Eos Sciences News by AGU), 2 March 2022. Press release.

Ocean Acidification