ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Global Change and the Future Ocean
Volume 12 - 2025 | doi: 10.3389/fmars.2025.1602158
Ocean liming effect on a North Atlantic microbial community: changes in composition and rates
Provisionally accepted
Inês De Castro1,2*
Susana C. Ribeiro1,2
Antonio Miguel Louvado3,4
Newton Carlos Marcial Gomes3,4Mário Cachão5,6Eduardo Brito De Azevedo1,2
Joana Barcelos E Ramos1,2- 1University of the Azores, Ponta Delgada, Azores, Portugal
- 2Institute of Agricultural and Environmental Research and Technologies, University of the Azores, Angra do Heroísmo, Portugal
- 3Centre for Environmental and Marine Studies (CESAM), Aveiro, Portugal
- 4University of Aveiro, Aveiro, Aveiro, Portugal
- 5Dom Luiz Institute, Faculty of Sciences, University of Lisbon, Lisboa, Portugal
- 6Department of Geology, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
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The ongoing rise in atmospheric CO2 levels and the consequent global warming make it increasingly difficult to maintain the global temperature within the 1.5 -2°C target set by the Paris Agreement. Therefore, strategies to remove carbon dioxide from the atmosphere are being developed, with ocean alkalinity enhancement (OAE) gaining most attention. Within OAE, ocean liming-the addition of quicklime (CaO) or hydrated lime (Ca(OH)2)-can not only remove CO2 from the atmosphere but potentially counteract the effects of ocean acidification. Although quite attractive, these technologies have yet to be tested regarding ecological safety and efficacy. Here we report the impacts of ocean liming on the abundance, composition and extracellular enzymatic activity (EEA) rates of a North Atlantic planktonic community. The results demonstrate that OAE led to a delayed phytoplankton development, mainly diatoms. The bacterial response to OAE was community-specific, with a consistent increase in the relative abundance of the order Oceanospirillales. OAE also led to increased EEA rates, especially within the bacterial community. These findings suggest that while initial effects on phytoplankton may be limited, the specific impacts on bacterial groups suggest that OAE could influence the remineralization of organic matter. If our results apply to other communities, OAE might initially affect marine microbial dynamics, but further studies are needed to determine if these effects are long-term.
Keywords: OAE, Phytoplankton, Marine heterotrophic bacteria, Extracellular enzymatic activity, 16S, global change, Microbial loop, Carbon dioxide removal
Received: 28 Mar 2025; Accepted: 30 Jun 2025.
Copyright: © 2025 De Castro, Ribeiro, Louvado, Gomes, Cachão, Brito De Azevedo and Barcelos E Ramos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Inês De Castro, University of the Azores, Ponta Delgada, 9501-801, Azores, Portugal
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