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PRI's Environmental News Magazine

Disappearing Coral Reefs

Air Date: Week of March 7, 1997

One of the world's most important living systems lies just out of view, in the ocean. Every four years the world's leading coral reef experts gather to try to assess the present health of the world's reef ecosystems. Bob Carty reports from Panama, with snorkel in hand, on the latest findings.


CURWOOD: This is Living on Earth. I'm Steve Curwood. Coral reefs are some of the most beautiful, diverse, valuable and endangered environments on Earth. Already, perhaps 10% of the world's reefs have suffered serious harm, and researchers predict that unless something can be done, most coral reefs will be lost during the next century. Every 4 years, the world's coral reef experts gather to take a snapshot of the global health of the world's most productive ecosystem save for tropical rainforests. Recently, the International Coral Symposium took place in Panama. Living on Earth contributor Bob Carty took along his mask and snorkeled to join them. He prepared this report.

(Waves and gulls)

PORTER: We're standing now on the Galeta Reef Flat in Panama. Galeta Reef is important because we have more records here of the population structure of plants and animals than on any other coral reef in the world. And coming back here after 25 years is really an emotional thing for me because it's changed.

CARTY: Jim Porter is an ecologist from the University of Georgia with a special attachment to Galeta Reef. Twenty-five years ago, Jim Porter did his PhD research here, counting corals day after day in the waters just a bit east from the Atlantic entrance to the Panama Canal and just a bit west of the rainforests of Panama's Darien Province. Twenty-five years later, Dr. Jim Porter is putting on his mask and snorkel with the eagerness of a schoolboy. He wades into the water and swims out to the reef to see if, like elsewhere around the globe, Galeta is in decline.

(Splashing in water, breathing through mask)

PORTER: There's a lot less coral here. There's definitely less coral. The big change to me (splash) is the loss of the alcord coral and its replacement by the stubby little fire coral. That would be like taking a forest of giant redwood trees and replacing it with a poison ivy patch.

CARTY: In the water around Jim Porter, a dozen other scientists are also floating over the Galeta Reef. This is excursion day, a chance for the participants of the Eighth International Coral Reef Symposium to trade their file folders for flippers. But all during the week, back in Panama City, they've been assessing the state of the world's coral reefs. The report card is not good.

(Ambient mulling conversation)

MAN 1: Well, this used to be a wonderful, joyous occasion of people coming together to talk bout what they love. I think we now all realize, those of us who have children, that our children may never see what we've spent our lives studying. It casts a pall.

WOMAN 1: We are loving our reefs to death. Six million divers a year visit the Florida Keys, but are unaware of the impacts that their very visitation is causing. Some scientists predict that our reefs will be gone within five years.

MAN 2: Seventy percent of the reefs are rather severely damaged, under immediate threat, or in a chronic state that if we don't do something about it in the next few generations we'll lose them as well, or they'll become so severely degraded that we won't be able to call them coral reefs as such.

WOMAN 2: It has been said that the first generation to enjoy scuba may be the last to see our coral reefs.

(Splashing, snorkeling)

PORTER: Well, beneath us, there are 4 common species. I'm expecting on a similar day under similar conditions in the past I would see 26 species. I've just begun my count here, I have 4 -- no, I've got 5 now. They're star coral, brain coral, some branching coral, lettuce coral. The commonest species are still here with the exception of the branching coral that's almost all gone. But the rare species don't seem to be here; I can't find them.


CARTY: Coral reefs cover less than one fifth of one percent of the ocean floor, but their contribution to ocean ecosystems is enormous. Reefs protect coastlines and help maintain the pH balance of the sea. They are nurseries and breeding grounds and feeding habitats for a quarter of all the ocean species. Corals are actually tiny animals smaller than a pencil eraser. They excrete limestone and slowly build structures that resemble bulbous brains or branching bushes. They also have live-in partners, a type of algae that gives the coral food and oxygen in return for shelter. But this mutually beneficial relationship is sensitive to numerous environmental stresses and diseases. Humans are the main culprit. Jeremy Jackson, a biologist at the Smithsonian Tropical Research Institute, says one of the major threats to coral reefs is overfishing.

JACKSON: Many of the fish that are taken are fish that consume the enemies of coral. Basically, seaweeds, which are normally cropped back by grazing fishes. When the fishes are removed, then there's nothing there to consume the seaweed and their naturally more rapid growth rate results in their very, very rapid overgrowth and killing of corals.

CARTY: Overfishing has been exacerbated by the use of some strange but efficient fishing techniques. In parts of Southeast Asia, fishermen make homemade explosives, a pop bottle with some commercial fertilizers and a fuse, to kill fish. But in the process reefs are blasted apart. In the Philippines, more than 300,000 pounds of cyanide is used each year to stun and catch tropical fish for aquariums. In the process, reefs are poisoned and coral habitats destroyed. In addition to overfishing, there is another major human made threat to coral reefs.

(Snorkeling sounds)

PORTER: It's hard to see very much through this water, and that was not the case before. This brown stuff that's here is sediment coming off from the land. I mean if I lift my head above the water here, I can see the Darien off in the distance, and it's mostly green, but then there are these fires. And there are places that people have cleared. That's the sediment that's moving down into the water. That's what's turning it brown.

CARTY: Runoff from the land threatens coral in several ways. On Galeta Reef, the sediment in places is 3 feet deep, entirely covering some corals. That's mostly because of deforestation. Other corals have been killed off by human pollution, such as a major oil spill that happened here 10 years ago. And some corals here are being smothered by algae. The runoff from the land has introduced nutrients like agricultural fertilizers, and the algae just love it. Biologist Jeremy Jackson.

JACKSON: All of these different processes work in the same direction. The increase in nutrients favors seaweeds against corals. The runoff of sediments favors seaweeds against corals. The removal of the fishes favors seaweeds against corals. And so there's this unfortunate dynamic where the principle insults to the environment all seem to be working in the same direction.

CARTY: Not all reefs are being threatened by overfishing and pollutants. In remote parts of the ocean far from human populations, reefs are doing just fine. But that may not be the case for long. There is now a new global threat to coral.

PORTER: There are some corals that are showing signs of distress. They've turned white. The whiteness is striking even through this turbid water. You can see the skeletons as they face upward and they look like white dinner plates dropped on the bottom. The white corals are called bleached corals.

CARTY: In the last 15 years, bleached corals have been showing up all around the world. Scientists fear it's a sign of global warming and the rise of ocean temperatures. It's a subject being studied now by Barbara Brown, a marine biologist at the University of Newcastle upon Tyne.

BROWN: Corals are normally brown or pink. The color is mainly derived from these plant cells which live inside the coral. But when they bleach they can turn completely white. Corals live close to their lethal temperatures. If the temperature exceeds seasonal maximum by one degree, then the corals lose their algae and bleach. And so our prediction for coral reefs is that they are going to bleach more and more regularly and perhaps with greater and greater intensity. And the real question is, can corals adapt to increased seawater temperatures?

CARTY: Dr. Barbara Brown believes that some corals may be able to respond to global warming by migrating to cooler waters. But that won't help the people who depend on reefs. As biologist Jeremy Jackson explains, in many countries coral reef survival is essential for the survival of people. For the health of their economies and for the stability of their societies.

JACKSON: Tourism represents really one of the greatest hopes for the economies of island nations and the decline of coral reefs represents the cutting off of the livelihood, of vast sectors of the populations of countries like Jamaica, Barbados or the Virgin Islands. They also provide an ever-diminishing but yet still important marginal source of nutrition. More than half of the protein to those peoples. The collapse of reefs and the associated fisheries is therefore a genuine calamity.

(Splashing water)

PORTER: Coral reefs are by far the most diverse environments on Earth. Even a tropical rainforest contains only 8 of the major divisions of animal life called phylum, but on this coral reef there are 33 phyla. Different ways in which animals have learned to survive on planet Earth.

CARTY: That means that each time a reef species dies, it's like destroying a unique library of genetic information and possible cure for a deadly disease. Drug companies and government agencies are now investigating the use of compounds that come from coral reefs, coral fish, and coral plants for treating cancer, arthritis, leukemia, and AIDS. Coral skeletons are even being tried in bone transplants. The pharmaceutical value of reefs may be as great as rainforests, which is one reason why Steve Hubble was invited to the reef symposium. Steve Hubble is a professor of ecology at Princeton and a specialist on rainforest conservation. He believes the techniques for saving jungles can be applied to corals.

HUBBLE: One of the things we've learned from rainforests is that you need a large area to preserve biodiversity, and the same thing is true for corals. They're much more dispersive as organisms than trees, so you have to worry about the meta-community, as it were, over a huge area like the Caribbean or the western Pacific. The whole system is interlinked. The advice to coral people is that -- and to policy makers, is that we have to think about very large reserves but also a regulatory commission on the conservation of coral reefs-- like the Whaling Commission.

CARTY: Large reserves and international regulatory commissions are only part of the answer. Two years ago 8 governments, including the United States, set up a partnership with international institutions and environmental groups. The International Coral Reef Initiative is trying to help national governments conserve their reefs and find ways to use them sustainably. Claude Wilkinson, an Australian scientist, says that means finding a way to assist the poor people who live near, and from, coral reefs.

WILKINSON: I think we need to get people involved. There's an interesting community-based project in the Philippines; it's been running for about 20 years now. A guy named Anga Alkala sat down and quietly and patiently talked to the local villages and convinced them that if they set aside 25% of their coral reefs as a reserve, they would catch more fish on the outside. Okay, at first they were skeptical. But then they came on board, they worked with the scientists and then they noticed themselves that the fish were getting bigger outside. Plus, they've got tourists coming to look at their marine reserve. So they're on a double win, they're win-win.


PORTER: The boat has just passed over 2 large coral heads almost 6 feet in diameter and both of them are dead. One of them is covered by a black sponge, which has replaced the living coral tissue.

CARTY: Jim Porter is finishing his swim over the Galeta Reef. It's been just a brief survey, 25 years since his earlier studies here. But he's seen enough to know that there are definitely less coral here and fewer varieties. It makes him somewhat sad.

PORTER: My memories of this place were sun-filled and now colors just aren't as bright.

CARTY: And the colors are not bright in 93 countries around the world, where human activity has damaged coral reefs. Understandably, the scientists who study corals are a somber lot these days. But they are not without hope. Corals, after all, have been around for millions of years. There's every reason to expect that they can make a comeback, if we stop harming them. For Living on Earth, I'm Bob Carty on Panama's Galeta Reef.

PORTER: Over here, one of the branching corals that we thought was going to be entirely gone is still here. There are little ones that have settled, juveniles, and they look like they -- they're growing. So maybe in 5 years we'll know whether this is a story of loss or hope.



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