Nancy Knowlton gives lecture during Voices of Discovery Tour on global warming’s impact on coral reefs

Sarah Beth Costello
February 19, 2009

Coral reefs - dubbed the underwter rainforests - provide shelter and provision for thousands of species. In recent years, coral reefs have slowly been dying out, a dillema that affects more than just the reefs.

Coral reefs - dubbed the underwater rainforests - provide shelter and provision for thousands of species. In recent years, coral reefs have slowly been dying out, a dilemma that affects more than just the reefs.

In 1975 the Caribbean waters just off the coast of Jamaica were teeming with the vibrant colors of coral reefs, tropical fish, sea anemones and a variety of underwater wildlife.

Almost thirty-five years later, the reefs are nearly unrecognizable. Instead of healthy, living corals, much of the remaining corals are slowly deteriorating and becoming little more than skeletal graveyards.

Coral reefs have been likened to the “rainforests of the sea” and are the life sources for thousands of sea creatures. But in the course of a few years, thousands of coral reefs not only in the Caribbean, but also worldwide, have been dying out.

This relatively new reef “epidemic” is an issue that has recently been brought to the forefront of scientist’s minds.

Dr. Nancy Knowlton is a marine biologist who has spent the majority of her life studying the “evolution, ecology and conservation of coral reefs.” Knowlton visited Elon University in Elon, N.C., Wednesday, and gave a presentation on coral reefs and global warming as part of the Voices of Discovery Tour.

“In the Caribbean we’ve lost 80 percent of all the living coral in the last 30 years…that’s a huge loss,” said Knowlton who spent several years studying coral reefs in the Caribbean region.

Knowlton compares the slow extinction of coral reefs to the destruction of rain forests, although the situation is much worse for the reefs. “The losses,” Knowlton said in reference to the reefs, “if anything are more severe than what we’ve seen in the tropics on land.”

Why the seemingly sudden demise of living coral reefs? The answer lies in human cohabitation. Most reefs survive near coasts that are inhabited by humans. Humans are responsible for foreign and alien substances that have entered into the natural habitats of corals and caused destruction.

CO2, waste, sediment and toxins are negatively impacting the environments. In addition to dumping unnatural content into the ocean, humans are also removing anything larger than five inches, including fish and corals.

Coral Afflictions

Knowlton focused her presentation on three dominant concerns for coral reefs: disease, bleaching and ocean acidification.

“Unfortunately, there are almost more coral diseases than there are coral doctors,” said Knowlton. In the majority of disease cases, scientists are at a loss about the causes. “In general,” said Knowlton, “it would appear that warmer water and dirtier water are contributing factors.”

Coral reefs grow at the rate of one centimeter or half an inch per year. The death of an entire reef is literally the death of a centuries-old organism. Some skeleton-like corals may possess an ethereal beauty, but in reality, a bleached coral is either dead or near death. Coral bleaching is a symptom of stress. Stress often results from heat, light, cold and dark. “It turns out that corals only live about a degree centigrade (about two degrees Fahrenheit) over their normal thermal maximum,” Knowlton explained.

There is some good news in terms of coral bleaching, however. Some corals possess resistance to bleaching and retain a patchiness of live coral. Scientists are hopeful that many corals will remain resilient.

Acidity in the ocean is a serious concern that Knowlton says has caused “coral osteoporosis.” Highly acidic water causes the structures of the corals to disintegrate, resulting in unsupported corals that are similar to sea anemones.

Fortunately, the corals can bounce back to health when placed back into healthy and natural waters. Scientists now know that corals can survive acidic lab waters, but it is still unknown as to weather acid-afflicted corals can survive in natural habitat.

Looking Towards the Future

environment1Reefs do not exist solely for aesthetic purposes. Thousands of organisms depend on coral reefs in order to survive. It’s a giant system where interaction and dependence is imperative for an underwater community to exist. The sharing of nutrients and protection makes it possible for the complexity of the millions of species to cohabit.

Knowlton showed two pictures of Barbados as examples of the drastic changes occurring in the Caribbean. “Just in the course of 50 years 18 percent of the reef has actually vanished and turned into sand,” she said.

The conservation of reefs is an important issue because it affects economies, industries, food availability and the overall environment. Improving water quality and controlling fishing are two huge steps governments can take in combating this issue.

“As a scientist all I can do is say…what the world would be like if we do this, versus what the world would be like if we do that,” said Knowlton as she concluded her presentation, “… but paraphrasing President Kennedy: ‘ask not only what your planet can do for you, but also what you can do for your planet.’”

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