Coral Reefs Feel the Stress of Global Warming

Learn more about coral reefs and global warming
Jane McClanahan, Elizabeth Lorence, and James Cervino, PhD

Jane McClanahan, Elizabeth Lorence, and James Cervino, PhD

Coral Reef with Yellow Band Disease Ring

Coral Reef with Yellow Band Disease Ring

Healthy Coral Reef

Healthy Coral Reef

Jane McClanahan and Elizabeth Lorence

Jane McClanahan and Elizabeth Lorence

Coral Reef with Multiple Yellow Band Disease Rings

Coral Reef with Multiple Yellow Band Disease Rings

Dyson students interested in preserving the Earth’s coral reef systems are making waves this year at the 106th General Meeting of the American Society for Microbiology (ASM). Dyson biology majors Jane McClanahan and Elizabeth Lorence, and Pace Biology Lecturer James Cervino, PhD, will present their research findings at this year’s ASM meeting on May 24.

In this student/faculty research project on the Lower Manhattan campus, the team of researchers has been looking for the connections between global warming, rising ocean temperatures, and the decline of coral reef ecosystems. Their findings are compelling.

Jane McClanahan explains. “Our lab research has been focused on the symbiotic algae, called zooxanthellae, that have a mutualistic relationship with the coral. When they’re subjected to higher water temperatures, like those we find in our oceans today, we want to know: What happens to the symbiotic algae? What species of zooxanthellae are susceptible to the Vibrio bacterial infection that causes Yellow Band disease found in these algae, and how do they die? This is important to know because when the algae die, the coral reef loses the nutrients, oxygen and energy that the algae produce, which the coral reef needs to survive. So they, in turn, also die.”

Why the study of coral reef systems?
“My interest was piqued in a marine biology class that I took with Professor Cervino,” says Elizabeth Lorence. “In learning how coral reefs are dying, and that this phenomenon is related to rising ocean temperatures and global warming, I felt it was very important to better understand this and to spread the word that global warming is an important problem that we need to solve. I truly feel a sense of mission about promoting awareness of global warming ? and the fact that it is happening right now.”

In laboratory tests that simulate the natural environment, the algae are subjected to heat stressing and then injected with the Yellow Band disease-causing pathogens. As a result, student researchers have found that the symbiotic algae cannot fight off the pathogen, causing them to become more susceptible to the disease. Additionally, they have found that the Yellow Band-causing Vibrio bacteria become more virulent and plentiful as a result of the higher temperatures. Vibrio bacteria also cause mass mortality in shell fish aquaculture stocks and are responsible for cholera that is a major cause of death in third world countries.

The canary in the coal mine.
“This double-edge sword result is what we have suspected,” says Cervino. “It doesn’t take much of a rise in water temperature to see this effect. We’ve tested at a mere 1 to 2 degrees Celsius above the average temperature during the warmest months of the year, and we’re seeing these results.” Coral reefs are very sensitive to temperature change and are considered leading indicators of global warming due to excessive burning of fossil fuels and other environmental stresses caused by human interactions such as blast fishing and the over-fertilization of lawn grasses. The scientific community has been studying and documenting how global warming is contributing to the rise of ocean temperatures for the past 20 years.

A vital habitat of our global ecosystem, coral reefs provide coastal protection, fish protein, biodiversity, and both life sustaining and economic value to indigenous populations by way of the tourism industry in Caribbean countries. Since they are one of the most climatically sensitive ecosystems on the planet, they are known as the “canary in the coal mine,” which can sense gases long before they become deadly in coal mines. McClanahan, Lorence, and Cervino hope to add to the growing body of evidence about global warming ? and its connection to diseases ? and contribute to reducing it before the world’s coral reef systems entirely perish.

McClanahan, Lorence, and Cervino have co-authored and will present the abstract “Vibrio Infection Intensifies Following Thermal Stress on Zooxanthellae Clade Species in Culture and in the Pacific Anemone Stichodatyla SP. [species]” at the ASM meeting. Other co-authors include researchers from the Universidade Estadual de Campinas, Brazil; Global Coral Reef Alliance, Cambridge, Massachusetts; The Institute of Earth Sciences at Hebrew University, Jerusalem, Israel; Howard University College of Medicine, Washington, DC; and University of South Carolina at Aiken.

Visit the American Society of Microbiology Web site for more information about the annual meeting: http://www.asm.org.