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18. World’s Coral Reefs Dying


January 2001
Title: Shoals Of Time: Are We Witnessing The Extinction of the World’s Coral Reefs?
Author: Julia Whitty

Faculty evaluator: Ervand Peterson
Student researcher: Connie Lytle

One-quarter of all coral reefs have been destroyed by pollution, sedimentation, over-fishing, and rapid global climate change. Coral reefs have survived enormous changes in our planet’s past, but today they are experiencing challenges from a multitude of new fronts. Remaining reefs are in such peril that governments are preparing for the contingency that millions of island residents will need to be relocated.

Corals are among the simplest of invertebrate animals. They are composed of little more than a hollow tube, the gastric cavity, which is surrounded by a fringe of stinging tentacles with which they capture prey. Generation after generation of new corals grow atop the limestone skeletons of dead corals, until a reef is formed. The growth is less than one inch per year, and the colonies can live a thousand years or more. Coral colonies occur in the narrow band of equatorial water at the 21°C isotherm, where the delicate balance between sunlight, temperature, salinity, nutrients, and gases meets the exacting requirements of the tiny coral animals, and compose the largest aquatic architecture on the planet.

Ordinarily, more than 6.5 million zooxanthellae inhabit each square inch of coral, and in return these algae contribute the by-products of their photosynthesis: oxygen, carbohydrates, and alkalinity. The corals’ calcium carbonate production is considered a likely mediator of atmospheric CO2, making this collaboration between plant and animal a contributor to the stability of our atmosphere. The reefs contain nearly one-quarter of all marine life and, as they are visibly altered by climatic and sea level changes, are often called “the record-keepers of the sea.”

Under assault from pollution, coastal development, agricultural runoff, overpopulation, and over-fishing, the world’s reefs are exhibiting their vulnerability in many ways. Each year new coral diseases are discovered, some caused by such factors as the desertification of Africa, where huge volumes of dust in the atmosphere are dropping viral and fungal spores onto the weakened seas.

In the last two decades, worldwide coral bleaching events associated with higher seawater temperatures have destroyed reefs throughout entire ocean basins. Increasing global temperatures, resulting in a lack of proteins, lipids, and carbohydrates necessary for coral reproductive and skeleton building causes bleached corals. A 1991 bleaching event in French Polynesia led to the death of 25% of all Acropora corals. The 1997-98 El Nino killed 70% of all corals in the Indian Ocean from Africa to India, and the reefs of the Galapagos Islands have yet to show signs of recovery from the bleaching event 17 years ago. Increases in ultraviolet rays entering the atmosphere have contributed to the bleaching effect in the coral reefs worldwide.

The worldwide trade in aquarium fishing, currently worth $200 million per year, is another source of coral reef destruction. The collection methods of exotic fish include using poisons, primarily sodium cyanide, which destroy entire ecosystems in order to capture the few remaining fish on the perimeter. Blast fishery, also common in such places as the Philippines, is a practice whereby fish for local consumption are collected with explosives, killing the fish at the epicenter, and incapacitating those on the perimeters. The blasts reduce the reefs to rubble, from which they may never recover.

UPDATE BY AUTHOR JULIA WHITTY: Since the publication of this article, I am now working on a book (“The Fragile Edge: Secrets & Struggles of the Coral Reef) for Houghton Mifflin. Research for this book will take me to Australia, the Philippines, Indonesia, and elsewhere, to show important new developments in the science and conservation of reefs. Some of the problems alluded to in the article are already coming to pass, as sea levels continue to rise and island-dwelling people face the loss of their homes and their nations. Elsewhere, conservation efforts are paying off, albeit on a fairly small scale.

I still consider the fate of coral reefs to be vital to our own well-being on earth. Sadly, this story, and other environmental stories, rarely make the evening news or the front pages of newspapers. As we fight a “war of national security” against terrorism, I wonder how it is that we fail to see or act upon the threats to global security that face us from the self-induced loss of biodiversity, the destruction of habitats, and global climate change. The “freedoms” and the “way of life” that we fight Al Quaeda for are at least as threatened by our continued misuse of the planet.

Harper’s Magazine originally offered me this article, so I had no struggle in trying to present it. But I know from years of making nature documentaries that there is strong resistance to telling the environmental truth—even when that truth can reveal important solutions.

Readers interested in learning more can track my coral travels (autumn 2002) at I will also be working closely with The Great Barrier Reef Research Foundation:

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