Articles | Volume 22, issue 2
https://doi.org/10.5194/bg-22-473-2025
https://doi.org/10.5194/bg-22-473-2025
Research article
 | Highlight paper
 | 
28 Jan 2025
Research article | Highlight paper |  | 28 Jan 2025

Assessment framework to predict sensitivity of marine calcifiers to ocean alkalinity enhancement – identification of biological thresholds and importance of precautionary principle

Nina Bednaršek, Hanna van de Mortel, Greg Pelletier, Marisol García-Reyes, Richard A. Feely, and Andrew G. Dickson

Related authors

Two Complementary Ocean Monitoring Indicators for Shelled Pteropods: Shell Dissolution and Habitat Suitability, 1995–2025
Alexandre Mignot, Nina Bednaršek, Sarah Albernhe, Stefano Ciavatta, Patrick Lehodey, and Jules Lehodey
State Planet Discuss., https://doi.org/10.5194/sp-2026-21,https://doi.org/10.5194/sp-2026-21, 2026
Preprint under review for SP
Short summary

Cited articles

Agostini, S., Harvey, B. P., Milazzo, M., Wada, S., Kon, K., Floc'h, N., Komatsu, K., Kuroyama, M., and Hall-Spencer, J. M: Seawater carbonate chemistry and kelp densities and coral coverages at three study locations and photosynthesis and calcification of corals measured in the laboratory, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.944056, 2021. 
Bach, L. T. and Mackinder, L. C. M.: Experiment: Dissecting the impact of CO2 and pH on the mechanisms of photosynthesis and calcification in the coccolithophore Emiliania huxleyi, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.830627, 2013. 
Bach, L. T., Riebesell, U., and Schulz, K. G.: Seawater carbonate chemistry, growth rate and PIC and POC production during experiments with Emiliania huxleyi (B92/11), PANGAEA [data set], https://doi.org/10.1594/PANGAEA.771288, 2011. 
Bach, L. T., Riebesell, U., Gutowska, M. A., Federwisch, L., and Schulz, K. G.: A unifying concept of coccolithophore sensitivity to changing carbonate chemistry embedded in an ecological framework, Prog. Oceanogr., 135, 125–138, https://doi.org/10.1016/j.pocean.2015.04.012, 2015. 
Bach, L. T., Gill, S. J., Rickaby, R. E., Gore, S. and Renforth, P.: CO2 removal with enhanced weathering and ocean alkalinity enhancement: potential risks and co-benefits for marine pelagic ecosystems, Front. Clim., 1, 21 pp., https://doi.org/10.3389/fclim.2019.00007, 2019. 
Download
Editorial statement
This paper warrants selection as a highlight due to its comprehensive synthesis of ocean alkalinity enhancement (OAE) impacts on marine calcifiers, offering essential insights for understanding potential ecological risks of this climate mitigation approach. By leveraging data from 96 studies and capturing responses across eleven biological groups, the paper establishes a predictive framework for biological responses to OAE. This work addresses a critical gap in OAE research, providing a precautionary guideline that can inform future studies, guide regional applications, and communicate risks to stakeholders.
Short summary
The environmental impacts of ocean alkalinity enhancement (OAE) are unknown. Our synthesis, based on 68 collected studies with 84 unique species, shows that 35 % of species respond positively, 26 % respond negatively, and 39 % show a neutral response to alkalinity addition. Biological thresholds were found from 50 to 500 µmol kg−1 NaOH addition. A precautionary approach is warranted to avoid potential risks, while current regulatory framework needs improvements to assure safe biological limits.
Share
Altmetrics
Final-revised paper
Preprint