This underwater jungle teems with life, from microscopic plants and animals to rays, sharks, large moray eels, and turtles. And here are some fish you may never have heard of—bright yellow clown fish, purple Beau Gregories, black-and-white Moorish idols, orange trumpet fish, dark blue surgeonfish, indigo hamlets, or brown and tan lion-fish. And how about barbershop shrimp, painted lobsters, or scarlet hawk fish? All colors, all sizes, all shapes. Some beautiful, some bizarre—but all interesting. See, there’s an octopus hiding behind that pillar coral! It’s dining on a clam it has opened. As in jungles on land, a tremendous variety of life is interwoven in the fabric of this marine world, all dependent on its diversity. Coral’s reproductive cycle and its ability to travel on ocean currents to build new reef communities was detailed in the June 8, 1991, issue of Awake!

Coral reefs form the largest biological structures on earth. One of these, the Great Barrier Reef, off the northeast coast of Australia, extends 1,250 miles [2,010 km] and encompasses an area the size of England and Scotland combined. A coral can weigh several tons and rise more than 30 feet [9 m] from the ocean floor. Coral reefs grow in all shallow tropical waters at a depth of as much as 200 feet [60 m]. They have characteristics that differ from area to area, so by examining a piece of coral, experts can tell the ocean and even the locale in which it grew. The environment needed for the growth of coral reefs is one with limited nutrients in the water, which explains why the ocean is unusually clear in their vicinity. Nutrition for the coral is supplied by algae (scientifically called zooxanthellae), which live in the polyp’s transparent body, and also by microscopic animals that are captured in the coral’s tentacles. The end result is a coral reef that is home to thousands of marine species in otherwise shelterless oceans.

Coral reefs are also the most biologically productive of all marine ecosystems. U.S.News & World Report described it this way: “Reefs are the marine equivalent of tropical rain forests, teeming with a profusion of living forms: undulating sea fans and sea whips, feathery crinoids, neon-hued fish and sponges, shrimp, lobster and starfish, as well as fearsome sharks and giant moray eels. All depend on the continuing industry of coral for habitat.” Coral reefs also support life on land by providing a barrier between crashing waves and shorelines and by laying the foundation for thousands of tropical islands.

Dying Coral Reefs—Are Humans Responsible?

THE 1992 International Symposium on Coral Reefs reported that people directly or indirectly have caused the death of 5 to 10 percent of the world’s living reefs and that another 60 percent could be lost in the next 20 to 40 years. According to Clive Wilkinson of the Australian Institute of Marine Science, only reefs in remote areas are fairly healthy. The newspaper USA Today stated that areas with damaged “reefs include Japan, Taiwan, the Philippines, Indonesia, Singapore, Sri Lanka, and India in Asia; Kenya, Tanzania, Mozambique, and Madagascar in Africa; and the Dominican Republic, Haiti, Cuba, Jamaica, Trinidad and Tobago, and Florida in the Americas. The causes of degradation vary, but high coastal populations and heavy coastal development are factors shared by all.”

Coral reefs normally thrive in seawater temperatures between 77 and 84 degrees Fahrenheit [25-29° C], depending on their location. But the narrow temperature range for healthy coral is very close to the lethal temperature. An increase of one or two degrees above the usual summer maximum can be deadly. While various causes can be identified for localized coral bleaching and its subsequent demise, many scientists suspect that a common worldwide cause may be global warming. Scientific American magazine reported on this conclusion: “The 1987 reports of coral bleaching coincided with escalating concern about global warming. It was not surprising, therefore, that some scientists and other observers reached the conclusion that coral reefs served as the canary in the coal mine—the first indication of an increase in global ocean temperatures. Although it appears that elevated local seawater temperatures caused bleaching, linking this effect to global warming cannot be conclusive at this time.”

U.S.News & World Report said: “Recent studies of the Caribbean have supported the hypothesis that abnormally warm oceans provoked the recent outbreaks.” Thomas J. Goreau, who heads the Global Coral Reef Alliance, pessimistically compared the plight of the reefs with the shrinking of the Amazon rain forest. “There will still be some rain forests left in fifty years,” he said, “but at the rate the coral reefs are going now, they won’t be around anywhere near that long.”

Destruction Worldwide—Many Causes

Along the Pacific Coast of Central America, up to 95 percent of the coral died in 1983. Similar but less destructive bleaching occurred at the same time in the central and western Pacific. Severe bleaching struck Australia’s Great Barrier Reef and areas of the Pacific and Indian oceans. Thailand, Indonesia, and the Galápagos Islands also reported damage. Thereafter, extensive bleaching took place near the Bahamas, Colombia, Jamaica, and Puerto Rico as well as southern Texas and Florida, U.S.A.

A worldwide pattern of destruction of reefs was emerging. Natural History observed: “In the relatively short time that reef ecosystems have been studied, bleaching on the recent scale has never been seen. Peter Glynn, a biologist at the University of Miami, has examined 400-year-old corals in the severely bleached eastern Pacific and has found no evidence of similar disasters in the past. The severe bleaching indicates that the general warming during the 1980s may have had a drastic effect on the coral reefs and may foretell the future of the reefs if the greenhouse effect leads to even warmer temperatures. Sadly, global warming and environmental deterioration will almost certainly persist and become more acute, increasing the frequency of worldwide bleaching cycles.”

U.S.News & World Report pointed to what could be another cause: “The thinning of the ozone layer, which shields living creatures from damaging ultraviolet radiation, may also bear some responsibility for the recent demise of reefs.”

In coastal areas, where over half the world’s population lives, human irresponsibility has heavily stressed coral reefs. A study from the World Conservation Union and the United Nations Environment Programme found that people had damaged or destroyed significant amounts of reef in 93 countries. Many developing areas flush their untreated sewage directly into the ocean, polluting it.

Mangroves, which survive in saltwater and filter impurities, are cut down for lumber and fuel. Reefs are torn apart and mined for building materials. In Sri Lanka and in India, entire sections of reef have been ground into cement. Ships large and small drop anchor on reefs or run aground on them, grinding them to rubble.

National Geographic magazine described what happens at Florida’s John Pennekamp Coral Reef State Park: “Their boats pollute the water and everything in it with petroleum products and sewage. Incompetent operators crash into the reefs. They litter the sea with plastic foam cups, aluminum cans, glass, plastic bags, bottles, and miles of tangled fishing line. This debris does not go away—it is, for all practical purposes, indestructible.”