bleached coral
Healthy corals live in symbiosis with algae in their tissue, which helps feed the coral through photosynthesis. However, too much heat or light damages cells in corals, resulting in the breakdown of symbiosis and the expulsion of the algae — a process known as coral bleaching. (Getty Images)

Testing a treatment to mitigate coral bleaching

A VCU Engineering researcher’s work could help coral populations survive in a warming world.

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The world’s largest coral reef is in danger, according to a report released by the United Nations in June. Coral bleaching, caused by rising sea temperatures, is a threat to the survival of the Great Barrier Reef and other coral colonies around the world.  

Addressing this problem is essential to the survival of coral populations, which, once lost, rarely reappear. It also would help preserve marine ecosystems, some of the most important wellsprings of Earth’s biodiversity.

VCU Engineering researcher Liza Roger, Ph.D., is developing a strategy to mitigate coral bleaching. She received a 2021 Early Career Training Program Award from the Coral Bleaching Research Coordination Network, an interdisciplinary program funded by the National Science Foundation.

Roger is a postdoctoral researcher in the lab of Nastassja Lewinski, Ph.D., an associate professor in the Department of Chemical and Life Science Engineering. Lewinski is leading coral cell culture research at Virginia Commonwealth University as part of a multi-university team studying ways to help coral survive.

Liza Roger, Ph.D.
Liza Roger, Ph.D.

“Using nanotechnology to save coral reefs is exciting, plus it challenges us to think deeply about nanoparticle-coral interactions and nanoparticles in the environment,” Lewinski said. 

Healthy corals live in symbiosis with algae in their tissue, which helps feed the coral through photosynthesis. However, too much heat or light causes oxidative stress, which damages cells in corals, resulting in the breakdown of symbiosis. That leads to the expulsion of the algae, making the skeleton visible through transparency of the tissue, the process commonly referred to as coral bleaching.

The early career training program provides opportunities in the study of coral bleaching in a partner lab. Roger’s award provides funds for travel and research supplies for her to perform experiments with two collaborators at the University of California, Riverside. 

Roger will investigate treating specimens of the symbiotic algae typically associated with corals with antioxidants to protect from bleaching, much like people eat foods rich in antioxidants to improve their health and fight aging. Since corals can’t eat foods like humans can, antioxidants are delivered in the form of nanoparticles too small to be seen by the human eye. 

Using a delivery method called reinfection, Rogers introduces the algae containing cerium oxide nanoparticles, a known antioxidant, into bleached corals in hopes the coral will form a new symbiotic relationship with the antioxidant algae and benefit from it. 

close-up of cauliflower coral or lace coral
Pocillopora damicornis, commonly known as cauliflower coral or lace coral, from the lab of Nastassja Lewinski. (Courtesy of Liza Roger)

Bleached corals can recover if environmental stressors subside, she said. “We can’t dial down the heat or light intensity for them, so if we can give them a treatment to mitigate the effect, we can hopefully help them get over the heat wave.”

She also investigates the delivery, trying to find a method that is practical for scaling up the treatment to all corals and reefs. The reinfection method seeks to deliver the antioxidants into the algae’s chloroplast to promote and protect the photosynthesis process, with the idea that the coral then works with the algae as part of its typical symbiosis process.  

Part of fine-tuning this delivery system includes determining the right dosage of antioxidant nanoparticles that are beneficial for the coral, but not harmful to other organisms that eat algae, such as fish.  

“We need to control all of this,” Roger said, explaining that these ecosystems are critical and “are biodiversity hot spots because of the abundance and diversity of life.”

By the end of her work in California, Roger hopes to have determined the right concentration of nanoparticles to deliver just enough antioxidants to the corals via the algae. She also hopes to determine if the particles are being delivered to the right place and, once there, whether they are performing correctly.

Her hosts at UC, Riverside are Juan Pablo Giraldo, Ph.D., an associate professor in the Department of Botany and Plant Sciences, and Robert Jinkerson, Ph.D., an assistant professor in the departments of Chemical and Environmental Engineering and Botany and Plant Sciences. 

Roger also recently earned a Postdoctoral Independent Research Award from VCU that will enable her to work with researchers at England’s University of Southampton to “fingerprint” coral cells as a way to investigate the mechanism of coral calcification, which is also affected by environmental changes.