Overview

Increased atmospheric carbon dioxide (CO₂) levels, caused by the burning of fossil fuels and deforestation, is the primary driver of a process termed ocean acidification, where the addition of CO₂ to the surface ocean acts to increase seawater acidity and lower pH.

Why It Matters

Carbon dioxide gas dissolves so readily in seawater that approximately one quarter of human caused CO₂ emissions become sequestered in the ocean. Once in the ocean, CO₂ combines with water to form a weak acid, resulting in a change in the chemistry of the sea.

The Chemistry of Ocean Acidification

The other major change in seawater chemistry involves CO₂-driven changes in the solubility of calcium carbonate minerals (CaCO₃) used by many marine plants and animals to build their shells and skeletons.rnrnThe solubility of CaCO₃ minerals depend on the amount of dissolved carbonate ions in seawater.rnrnMore CO₂ and lower pH reduces the concentration of carbonate ions, making it more difficult for many organisms to make shell material.

Ocean CO₂ and pH from NOAA: Correlation between rising levels of CO2 in the atmosphere at Mauna Loa with rising CO₂ levels in ocean at Station Aloha.

Coastal & Estuarine Acidification Stressors Need for Information What’s Next

What’s Next

Task Force to Study the Impact of Ocean Acidification on State Waters Report to the Governor and the Maryland General Assembly

DOWNLOAD

What Lies Ahead

In 2009, Congress passed the Federal Ocean Acidification Research and Monitoring (FOARAM) Act, which required an interagency working group to create a Strategic Plan for Federal Research and Monitoring of Ocean Acidification. The reauthorization of FOARAM in 2022 strengthened investments in acidification research, monitoring, and improving understanding of socioeconomic impacts. Regional consortia like MACAN, New England’s NECAN, and the Southeast Atlantic’s SOCAN have formed throughout the country to focus on acidification in their respective territories.

States Take a Closer Look at Acidification’s Implications In Their Waters

Maryland

The Maryland Task Force was charged with analyzing the best available science and the potential effects of acidification on ecology to make recommendations for potential strategies to mitigate the effects of acidification in state waters and fisheries. In 2015, the Maryland Task Force produced the Task Force to Study the Impact of Ocean Acidification on State Waters Report for the Governor and the Maryland General Assembly calling for monitoring, industry partnerships and collaboration with federal agencies to address the threat.

New York

New York’s Ocean Acidification Task Force was charged with addressing the impacts of ocean acidification to coastal waters, identifying factors that contribute to acidification, and recommending actions to address negative impacts. Their 2023 report, Ocean Acidification: Its Causes, Impacts, and Mitigation; A Report to the New York State Legislature, recognizes the
cross-cutting nature of ocean acidification with climate, ocean and marine science priorities and lays out five pillars of actions, spanning research, education, engagement, and legislation, to mitigate and minimize the impacts in NY’s marine waters.

New Jersey

After joining the OA Alliance in 2021, New Jersey’s Department of Environmental Protection created an OA Team and initiated a comprehensive suite of research, policy analysis, and stakeholder engagement strategies to develop recommendations for a statewide monitoring network and a comprehensive Ocean Acidification (OA) Action Plan.

Acidification Will Continue to Influence All Areas of the Mid-Atlantic, From its Tidal Estuaries to Deep Sea Ecosystems

Acidification will continue to influence all areas of the Mid-Atlantic, from its tidal estuaries to deep sea ecosystems. The cooler, less salty waters of the upper Mid-Atlantic are particularly susceptible to ocean acidification, making reductions in the survival, calcification, growth, development, and abundance of marine organisms more likely. The organisms impacted most negatively and directly will likely be calcified algae, corals, mollusks, and echinoderms. Crustaceans, fleshy algae, seagrasses, and diatoms may be less directly affected or may even benefit from acidification. Even still, questions regarding food web impacts that may indirectly negatively impact all species remain.

Photo: MACAN-WhatIsAcidification-Tab4-Image01 (2)

Acidification May Hamper Efforts to Protect and Preserve the Mid-Atlantic’s Cultural Underwater Resources

The “Ghost Ship fleet” of Mallows Bay-Potomac River National Marine Sanctuary is one such resource. Anticipating damage to metal structures on the ships and other potential impacts, sanctuary managers are beginning to address climate change through their sanctuary management plans. As outlined in the report, Climate Change Impacts: Mallows Bay-Potomac River National Marine Sanctuary, strong partnerships between NOAA, the state of Maryland, and local organizations have been key to establishing a water monitoring network and supporting research on acidification and other climate stressors.

Photo: National Marine Sanctuary

Combating Acidification Won’t Be Easy, But Scientists, Governments, and NGOs Are Working to Identify Approaches to Help

Mitigation

Changing behavior and advancing technologies to decrease the carbon dioxide that causes acidification.

Remediation

Taking steps to lessen the acidity of water, such as planting eelgrasses that take up carbon dioxide.

Adaptation

Making changes in response to the symptoms of acidification, such as breeding shellfish that are more resistant to acidified waters.

Innovative Ideas for Mitigation, Remediation, and Adaptation of Acidified Waters Will Continue to Evolve

A consortium such as MACAN can help to guide resources for research in mitigation, remediation, and adaptation by collectively identifying the most critical research gaps.

Browse Macan’s Resources

References

EK Towle, AC Baker, C Langdon. 2016. Preconditioning to high CO2 exacerbates the response of the Caribbean branching coral Poritesporites to high temperature stress. Marine Ecology Progress Series; 546: 75-84. DOI: 10.3354/meps11655. https://doi.org/10.3354/meps11655

E Ramirez-Llodra, PA Tyler, MC Baker, OA Bergstad, MR Clark, E Escobar, LA Levin, L Menot, AA Rowden, CR Smith, CL Van Dover. 2011. Man and the last great wilderness: human impact on the deep sea. PLoS ONE 6(8): e22588. https://doi.org/10.1371/journal.pone.0022588

National Marine Fisheries Service. 2016. Fisheries Economics of the United States, 2014. U.S. Dept. of Commerce, NOAA Tech. Memo. NMFS-F/SPO-163, 237p.

RC Chambers, AC Candelmo, EA Habeck, ME Poach, D Wieczorek, KR Cooper, CE Greenfield, and BA Phelan. 2014. Effects of elevated CO2 in the early life stages of summer flounder, Paralichthys dentatus, and potential consequences of ocean acidification. Biogeosciences 11.6: 1613-1626. https://doi.org/10.5194/bg-11-1613-2014

GG Waldbusser, EP Voigt, H Bergschneider, MA Green, RIE Newell. 2011. Biocalcification in the eastern oyster (Crassostrea virginica) in relation to long-term trends in Chesapeake Bay pH. Estuaries and Coasts 34.2: 221-231. https://doi.org/10.1007/s12237-010-9307-0

Ekstrom, J. A., Suatoni, L., Cooley, S. R., Pendleton, L. H., Waldbusser, G. G., Cinner, J. E., Ritter, J., Langdon, C., Van Hooidonk, R., Gledhill, D., Wellman, K., Beck, M. W., Brander, L. M., Rittschof, D., Doherty, C., Edwards, P. E. T., & Portela, R. (2015). Vulnerability and adaptation of US shellfisheries to ocean acidification. Nature Climate Change, 5(3), 207–214. https://doi.org/10.1038/nclimate2508

Speir, C., Ryan, G., & Mayo, C. (2016). Fisheries Economics of the United States, 2014 (NOAA Technical Memorandum, p. 246). NOAA. https://spo.nmfs.noaa.gov/sites/default/files/TM163.pdf

Wang, Z. A., Wanninkhof, R., Cai, W.-J., Byrne, R. H., Hu, X., PenSabag, T.-H., & Huang, W.-J. (2013). The marine inorganic carbon system along the Gulf of Mexico and Atlantic coasts of the United States: Insights from a transregional coastal carbon study. Limnology and Oceanography, 58(1), 325–342. https://doi.org/10.4319/lo.2013.58.1.0325

Saba, G.K., Goldsmith, K.A., Cooley, S.R., Grosse, D., Meseck, S.L., Miller, W., Phelan, B., Poach, M., Rheault, R., St. Laurent, K., Testa, J., Weis, J.S., Zimmerman, R. 2019. Recommended Priorities for Research on Ecological Impacts of Coastal and Ocean Acidification in the U.S. Mid-Atlantic. Estuarine, Coastal and Shelf Science 225: 106188

Get Involved

If you are interested in learning more about MACAN and the work we do, please sign up for our monthly newsletter. You can also read our 2024 to 2028 Work Plan.

View Macan's 2024-2028 Work plan