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Assessing the effects and risks of ocean alkalinity enhancement on the physiology, functionality, calcification, and mineralogy of corals and crustose coralline algae in the Pacific

Coral Reef off the coast of Coconut Island in Kāneʻohe. Photo by Keisha Bahr

Why we care
One potential benefit of ocean alkalinity enhancement is reversing ocean acidification, which can impact marine life like corals, clams, and crabs. This project investigates the potential benefits and risks of ocean alkalinity enhancement on Pacific tropical and subtropical corals and crustose coralline algae. The project’s goal is to understand if ocean alkalinity enhancement can help counteract the effects of ocean acidification on coral reefs, which are important ecosystems for marine biodiversity and human communities. 

What we will do
The main objectives of the research are to identify how corals and crustose coralline algae respond to immediate alkalinity additions and to determine the effects of chronic and acute exposure to ocean alkalinity enhancement. The study will explore whether biological limitations are primarily attributed to alkalinity or other factors like potential trace metal toxicity from the minerals used in ocean alkalinity enhancement. Laboratory experiments using different alkalinity enhancement agents (quicklime, sodium hydroxide, and olivine) conducted in chambers and mesocosms will establish safe operating conditions and understand the mechanisms of calcification in corals and crustose coralline algae under different ocean alkalinity enhancement scenarios. The team will support inclusivity and equity in the field of marine carbon dioxide removal by offering paid internships for underrepresented groups. 

Benefits of our work 
“Understanding the intricate balance between alkalinity additions and coral response will contribute to developing effective and informed strategies for mitigating the impacts of climate change and ocean acidification” says Dr. Melissa Meléndez of the University of Hawai’i.  It is especially important to assess “potential benefits and limitations of ocean alkalinity enhancement, particularly in the context of safeguarding the health of corals.” The findings will provide valuable insights into the effects of ocean alkalinity enhancement on coastal ecosystems and guide the development of strategies that combine coral restoration and ocean alkalinity enhancement activities. The project team will provide training and educational opportunities for Pacific Islanders, community members, early-career researchers, underrepresented students, and stakeholders to learn about ocean alkalinity enhancement  approaches and their potential impacts on coral reefs. Ultimately, the research contributes to the development of sustainable carbon dioxide removal methods and ocean acidification mitigation on coral reef ecosystems.

Award amount: $1,999,835
Funding source(s): Department of Energy Office of Fossil Energy and Carbon Management
Project duration: 4 years

Melissa Meléndez, University of Hawai’i, Manoa
Keisha Bahr, Texas A&M, Corpus Christi
Hannah Barkley, NOAA Pacific Islands Fisheries Science Center
Nick Hawco, University of Hawai’i, Manoa
Conall McNicholl, University of Hawai’i, Manoa
Lisa McManus, University of Hawai’i, Manoa
Christopher Sabine, University of Hawai’i, Manoa

Read the webstory from the University of Hawai’i, Manoa and webstory at Texas A&M, Corpus Christi

Image: Ocean alkalinity enhancement may mitigate the effects of climate change and ocean acidification on coral reefs like this one off the coast of Coconut Island in Kāneʻohe, Oahu. Photo by Keisha Bahr

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The NOAA Ocean Acidification Program (OAP) works to prepare society to adapt to the consequences of ocean acidification and conserve marine ecosystems as acidification occurs. Learn more about the human connections and adaptation strategies from these efforts.

Adaptation approaches fostered by the OAP include:


Using models and research to understand the sensitivity of organisms and ecosystems to ocean acidification to make predictions about the future, allowing communities and industries to prepare


Using these models and predictions as tools to facilitate management strategies that will protect marine resources and communities from future changes


Developing innovative tools to help monitor ocean acidification and mitigate changing ocean chemistry locally


On the Road

Drive fuel-efficient vehicles or choose public transportation. Choose your bike or walk! Don't sit idle for more than 30 seconds. Keep your tires properly inflated.

With your Food Choices

Eat local- this helps cut down on production and transport! Reduce your meat and dairy. Compost to avoid food waste ending up in the landfill

With your Food Choices

Make energy-efficient choices for your appliances and lighting. Heat and cool efficiently! Change your air filters and program your thermostat, seal and insulate your home, and support clean energy sources

By Reducing Coastal Acidification

Reduce your use of fertilizers, Improve sewage treatment and run off, and Protect and restore coastal habitats

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You've taken the first step to learn more about ocean acidification - why not spread this knowledge to your community?

Every community has their unique culture, economy and ecology and what’s at stake from ocean acidification may be different depending on where you live.  As a community member, you can take a larger role in educating the public about ocean acidification. Creating awareness is the first step to taking action.  As communities gain traction, neighboring regions that share marine resources can build larger coalitions to address ocean acidification.  Here are some ideas to get started:

  1. Work with informal educators, such as aquarium outreach programs and local non-profits, to teach the public about ocean acidification. Visit our Education & Outreach page to find the newest tools!
  2. Participate in habitat restoration efforts to restore habitats that help mitigate the effects of coastal acidification
  3. Facilitate conversations with local businesses that might be affected by ocean acidification, building a plan for the future.
  4. Partner with local community efforts to mitigate the driver behind ocean acidification  – excess CO2 – such as community supported agriculture, bike & car shares and other public transportation options.
  5. Contact your regional Coastal Acidification Network (CAN) to learn how OA is affecting your region and more ideas about how you can get involved in your community
       More for Taking Community Action