Where have all our coral reefs gone?

By Henrylito D. Tacio



Coral reefs provide a fascinating sanctuary for an equally enchanting but silent kingdom of colorful sea inhabitants. They serve as breeding places, nurseries, and home for many marine vertebrates and invertebrates.

lthough corals are found throughout the oceans of the world in polar and temperate waters as well as in the tropics, it is only in the tropics that reefs are developed. Worldwide, there are approximately 600,000 kilometers of coral reefs, which are home to millions of fishes and other types of marine life. Experts estimate as many as 3,000 varied species of marine organisms dwell in a single reef. The largest number of coral species occurs in an area of the Indo-Pacific that includes the Philippine Islands, the Indonesian Archipelago, New Guinea and northern Australia.

Generous reefs
Corals are coelenterate animals (ray-like invertebrates) that form heavy skeletons of lime. Encrusting coralline algae grow on their surfaces and crevices, cementing them lightly to form reefs. Coral reefs do not develop in water that is deeper than about 50 to 70 meters. Most reefs grow in depths of 25 meters or less. Coral reefs and their resources - especially fish - have a significant impact on people's lives. An estimated 10-12 percent of the world's finfish and shellfish harvest in 1990, for instance, were coral reef species. In Southeast Asia, about 5 million people are employed in fisheries, contributing US$6,600 million annually to regional incomes. About 90 percent of these are small-scale fishermen employing traditional fishing methods, with coral reef fishery contribution of US$500 to US$1,000 million annually.

In the Philippines, an estimated 10-15 percent of the total fisheries come from coral reefs. About 80-90 percent of the income of small island communities comes from fisheries. "Coral reef fish yields range from 20 to 25 metric tons per square kilometer per year for healthy reefs," says Dr. Angel C. Alcala in his report during a plenary address at the 9th International Coral Reef Symposium (9ICRS) in Bali, Indonesia.

There are three major types of coral reefs. These are the fringing type (those found along the edges of the island and which constitute 30% of the country's coral reefs); the barrier type (best exemplified by the Danajon Reef of Central Visayas); and the atoll (of which the Tubbataha and Cagayan Reefs in the Sulu Sea are typical examples).

Alarming decline
The Philippines is home to more than 400 species of corals, more than what is found in the famous Great Barrier Reef of Australia. Unfortunately, most of these species are now gone and others are facing extinction. "Nowhere else in the world are coral reefs abused as much as the reefs in the Philippines," says Don E. McAllister of the Ocean Voice International. An analysis of more than 600 data sets showed that "excellent" reefs (live hard and soft coral cover above 75%) has been reduced from 5.3% to 4.3% since the late 1970s. If hard corals alone are considered, only 1.9% of the reefs can be called "excellent," with average hard coral cover on all reefs down to 32.3%.

The decline is thought to be due primarily to destructive human activities. "Many reef areas are in really bad shape, largely because of unwise coastal land use, deforestation and the increasing number of fishermen resorting to destructive fishing methods," says marine biologist Porfirio M. Alino of the University of the Philippines’ Marine Science Institute (UP-MSI).

Dynamite fishing
Destructive fishing methods are destroying vast areas of reef. Fishers blast reefs with dynamite, stunning, if not killing, fish several meters away. A single blast can make a hole up to 5 meters in diameter in branching coral colonies – with long-term effects. Heavily dynamited reefs produce only 2.7 to 5 metric tons per square kilometer per year compared to 30 metric tons for healthy reefs. The damage caused by dynamites to reefs goes beyond the shattering impact of the explosion itself. After a blast, algal growth quickly smothers the coral because the shoals of grazing fish that would normally keep it under control have been decimated.

Although illegal in most countries, dynamite fishing is still widely practiced in 40 countries, including the Philippines, because of economic need and poor enforcement of laws prohibiting it. In the Philippines, explosives have damaged an estimated one-sixth of reefs since 1945.

Use of cyanide
In many parts of the world, natural poisons have long been used in fishing without apparent damage. But such is not the case of sodium cyanide. In the Philippines, 80% of the exotic fish destined for pet shops and aquariums throughout Europe and North America are captured using cyanide. There is also a growing demand in upscale restaurants for live food fish, which are often caught with cyanide.

"The annual trade in aquarium and live food fish is worth at least US$1.2 billion wholesale," says Dr. Vaughan Pratt, president of the International Marinelife Alliance, a non-governmental organization based in the Philippines that is working to save the coral reefs of the Western Pacific.

Fishermen stun fish by squirting cyanide into the reef areas where these fish seek refuge, and then, using crowbars, they rip the reefs apart capture disoriented fish hiding in the corals.

Cyanide also kills coral polyps and the symbiotic algae and other small organisms necessary for healthy reefs.

According to the Coral Reef Alliance (CORAL), an estimated 330,000 pounds of cyanide is sprayed on Philippine coral reefs each year. "These practices are criminal," said Jacques-Yves Cousteau after a recent visit to Palawan to examine reefs destroyed by cyanide fishing. "They attack the natural productive environment which allows the renewal of marine resources. Destroying coral today is destroying tomorrow's fishes."

Cyanide fishing operations are moving from the over-harvested and devastated reefs of the Philippines to destroy remote and pristine coral reefs in eastern Indonesia, Papua New Guinea, Palau, Tuvalu, the Federated States of Micronesia, and other nations in the Western Pacific.

Muro-ami
Another equally destructive fishing method is the muro-ami, which was introduced by Okinawan fishermen before World War II. The muro-ami is a drive-in net used for fishing in coral reefs. It consists of a net bag with two long wings into which divers drive schooling fish. The gear utilizes vertical scarelines weighed down by stones or chain links for creating a disturbance that drives out the fish from the coral reef into the net.

Muro-ami is a high-yield fishing gear, but Dr. Rafael D. Guerrero III of the Philippine Council for Aquatic and Marine Research and Development pointed out, there are problems related to this method. They include, he said, the “employment of minors (young boys) for fishing, their exposure to health hazards (like the "bends" or narcosis) and the destruction of coral reefs because of the weighted scarelines."

A study conducted by marine biologists Ken Carpenter and Alcala in l977 showed that 50 divers operating the gear could damage as much as l7 square meters per hectare of coral reef per operation. A muro-ami fishing boat usually operates 3-4 times in a fishing season.

In the late 1980s, muro-ami was banned in the Philippines and was replaced by the large-scale, drive-in fishing technique called pa-aling. Prior to its approval as an alternative, pa-aling was found to incur minimal physical damage to corals. Recently, the technique has been reported to be as bad as muro-ami. Despite this, the operation of pa-aling continues in reefs of the South China and the Sulu Sea and in the vicinity of Palawan.

Coral mining, bleaching, etc.
Coral mining has also depleted the country's reefs. In fact, an estimated 1.5 million kilograms of coral are harvested annually as part of the international trade in reef products. The Philippines, according to the Panos Institute, supplies more than a third of this total, with Malaysia, Indonesia, New Caledonia and Fiji supplying another third. "The biggest demand comes from the United States, which has banned domestic coral mining," the Panos briefing on coral reefs states. "In 1989, the United States also banned the import of coral from the Philippines (where its export is illegal); however, supplies continue to arrive through illicit channels, and from Indonesia and Singapore."

In recent years, the phenomenon called bleaching has also threatened the country's sensitive coral reefs. From 1997 to 1998, massive coral bleaching -- in which corals turn chalky white -- was reported in Masinloc, Zambales; Bolinao, Pangasinan; Bacuit Bay, El Nido, and Coron Islands in Palawan; and Puerto Galera, Oriental Mindoro.

The whitening of corals, marine experts explain, is from the loss of zooxanthellae, an organism found in the tissue of polyps (a tiny flower-like animal connected by a membrane that covers the coral rock), exposing the coral's calcium component and usually causing its death.

Experts traced the recent mass bleaching to global warming. "An increase in temperature of at least one degree can cause coral bleaching. With the continued temperature increase in the world's oceans, bleaching is inevitable," says Robert Pabiling, National Power Corporation senior biologist in Zambales.

Also contributing to the destruction of coral reefs in the Philippines are sedimentation from erosion of soil from deforestation; the quarrying of coral reefs for construction purposes; pollution from industry, mining, and municipalities; and coastal population growth.

Benefits of reef protection
"The degradation of coral reef ecosystems in the Philippines and other places in could have dire consequences," says a State of the Reefs report distributed during the International Coral Reef Initiative a couple of years ago. "Its destruction can greatly reduce fish production, thus endangering the fish supply in the country." Coral reefs, after all, produce about four times more fish per unit compared to the coastal trawl fisheries, says Dr. John McManus, a marine biologist. There are 27,000 square kilometers of coral reefs in the Philippines.

Fish provides more than half of the protein requirements of Filipinos, but there's more to reefs than fish. "The extensive destruction of Philippine coral reefs has constricted the development of tourism in the country's coastal areas," contends McAllister. "If the coral reefs recover, there will enormous growth in coastal tourism. Today, with most of the coral reefs in a poor state, it is not an exaggeration to say that the country has lost one-third of its potential as a tourist spot in Asia."

According to Alcala, the aesthetic quality of protected coral reefs serves to attract tourists. He cites the case of Apo Island, off the southern coast of Negros. This 100-hectare marine protected area brings in some US$126,000 annually to the 600 inhabitants of the island and to a number of boat operations on the mainland Negros. Quoting officials from the Protected Area Management Board for Apo Sanctuary, he says that tourist fees alone amount to about US$40,000 annually.

More importantly, coral reefs are a potential source of many new medicines in the 21st century. "Marine sources could be the major source of drugs in the next decade," says Dr. William Fenical, a natural products chemist at the Scripps Institution of Oceanography in La Jolla, California. The U.S. National Cancer Institute (NCI) already spends one-third of its research budget to screen about 1,000 species of oceanic invertebrates and plants each year, including sea slugs, sea squirts, sponges, and several other denizens of coral gardens.

For centuries, coastal communities have used reef plants and animals for their medicinal properties. In the Philippines, for instance, giant clams are eaten to treat malaria. Chemicals from sea sponges collected off the coast of Florida have been used in developing a new drug, Ara-C, used to treat acute myelocytic leukemia and non-Hodgkin's lymphoma. The antiviral drug called Ara-A is used for the treatment of herpes infections.

Whether or not humankind gets to enjoy the undoubtedly still many untold benefits of coral reefs may be up to us. Says Guerrero, "We are the stewards of our nation's resources; we should take care of our national heritage so that future generations can enjoy them. Let's do our best to save our coral reefs. Our children's children will thank us for the effort."

US Vice President Al Gore puts it in more specific terms, "To conserve these natural treasures, we must reduce human impacts on coral reefs by immediately controlling pollution, reducing overfishing, increasing protection and sustainable use of our valuable coral reef resources. By working together -- from local communities to regions and internationally -- I believe we can, and must, reverse the tide of destruction and conserve the world's precious coral reefs."

Global warming: The reefs’ unseen enemy

On land, the ecosystem that supports the greatest number of plant and animal species is the rainforest. In the sea, it's the coral reef. Most of the coral reefs are located in the region bounded by Indonesia, Malaysia, and the Philippines. About 600 of the 700 species known to man have been discovered in this region.

Unfortunately, coral reefs are in a steady state of decline. "Like the tropical rainforests, coral reefs are being endangered by a diverse range of human-related threats," said the Washington-based World Resources Institute (WRI).

Depending on their location, reefs have been damaged directly through harmful practices such as coral mining, fishing with dynamite and cyanide, or overfishing in general; haphazard coastal development; or even careless pleasure diving by tourists. Reefs have also suffered indirectly from sediment from inland deforestation and removal of coastal mangroves; from industrial pollution; and from nutrient pollution contributed by sewage, fertilizers, and urban runoff.

Mass coral "bleaching" is yet another major contributing factor to decline of coral reefs in recent years, pointed out Dr. Ove Hoegh-Guldberg, the founding professor of marine studies and director of the University of Queensland's Center for Marine Studies, during the 9th International Coral Reef Symposium (9ICRS) held in Bali, Indonesia last month.

"Many of the papers presented during the symposium concerned key parts of the issues associated with coral bleaching," he said, quoting the statement of the scientific panel released during the press briefing convened by the Washington-based SeaWeb. "The fact that all major climate models show that the current increases in sea temperature will continue is a source of major concern.”

Corals grow in the warm waters, but many of them are near the limits of their tolerance for high temperatures. Bleaching is a breakdown of a "complex biological system" that corals have evolved in order to survive. Each coral formation is a colony of hundreds or thousands of tiny organisms (known as polyps) that jointly build a skeleton that forms the reef. On the outside layer of each coral polyp live tiny one-celled plants scientists called zooxanthellae. It is these organisms that give the coral its bright colors, and when expelled due to warmer water or some other stress, coral appears bleached (that is, go pale or snowy-white). Without zooxanthellae, the coral cannot survive for long.

"Corals tend to die in great numbers immediately following coral bleaching events, which may stretch across thousands of square kilometers of ocean," explained Dr. Hoegh-Guldberg, who has studied the phenomenon of coral bleaching since the early 1980s.

According to the book, Management of Bleached and Severely Damaged Coral Reefs, coral bleaching can be traced to as far back as 1870. However, since the 1980s, bleaching events have become more frequent, widespread and severe. "The massive coral bleaching and mortality event of 1998 devastated large parts coral reefs around the world," WRI deplores.

The most affected reefs were in the Arabian/Persian Gulf, Kenya, Tanzania, the Seychelles, Maldives, Chagos banks, Sri Lanka and India in the wider Indian Ocean, parts of Southeast Asia, especially Vietnam, the Philippines, Taiwan, southern Japan, and Palau. Many areas reported coral losses of 60-90% over large areas and often down to 30 meters or more.

A report released by Greenpeace cites "warmer than normal temperatures" as the principal cause of the massive coral bleaching and mortality event. "Increased sea temperature is the primary reason why coral bleaching has occurred with increasing intensity and frequency over the past two decades," the report states.

"Sea surface temperatures throughout the tropics have shown dramatic increases over the last two decades, as much as half a degree per decade," said Dr. Al Strong, team leader in the satellite research at the US National Oceanic and Atmospheric Administration. "This is ten times what we are observing globally."

Dr. Thomas J. Goreau of the New York-based Global Coral Reef Alliance (GCRA) traces the recent "warmer than normal temperatures" to global warming. "Global warming is apparent in the worldwide proliferation of coral bleaching," declares Worldwide Fund for Nature (WWF) based in Washington, D.C.

The warming of the world is due to the increase of heat being trapped in the atmosphere by greenhouse gases such as carbon dioxide and methane. The five warmest years in history have all been recorded in the last two decades, and there has been an unprecedented increase in the numbers of coral bleaching events during this period.

The worst bleaching episodes have coincided with a strange weather event known as El Niño. El Niños are periodic natural weather cycles, which originate in the Pacific but can cause water temperatures to rise and extreme weather (hurricanes, droughts, and floods) around the world.

According to WRI, the recent massive coral bleaching was caused by the combination of extremely calm conditions during the 1997-98 El Niño events, coupled with a steady rising baseline of sea surface temperatures in the tropics. "These drove temperatures in parts of the tropics above records for the past 150 years, and bleaching was indiscriminate; impacts were equally severe on pristine, remote reefs as on reefs already under major human stresses," says the Status of Coral Reefs of the World: 2000, which was released during the 9ICRS.

"It will be several years before we can state that reefs will recover, or whether there will be local losses of species, including some rare endemic species," says Dr. Clive Wilkinson, editor of the 2000 status report. "Reef recovery will depend on few or no repeats of the extreme events of 1997-98, and even then, it will take 20 to 50 years before reefs recover to structures resembling those before the bleaching."

Dr. Goreau said that coral reefs are the first ecosystem to suffer large-scale damage from climate warming. "Coral reefs are uniquely threatened by global warming, because they cannot relocate to more favorable conditions or be replaced by immigrant organisms from warmer zones," he explained.

The Greenpeace report shares the same warning: "Coral bleaching events are projected to steadily increase in frequency and intensity until they occur every year by the 2030 to 2070 if greenhouse gases emissions continue to rise unabated."

According to Dr. Goreau, bleaching and diseases have caused more coral deaths in the last couple of years than all previous human damage to reefs. "Unless bleaching and disease are reduced, all efforts at reef protection will be futile," he pointed out. "Recovery of coral reefs from mortality caused by severe bleaching and diseases is likely to be very prolonged, if it happens at all.”

Coral reefs damaged by severe local stresses such as ship groundings, hurricanes, or predatory pest outbreaks can recover in a few decades as long as surrounding reefs are healthy. "However in recent years we have seen virtually all colonies of the most abundant and rapidly growing branching and plate corals in the Indian Ocean and parts of the Pacific die," Dr. Goreau said.

Warming waters aren't the only threats posed to coral reefs by climate change. Many scientists believe that global warming will herald a new era of extreme and unpredictable weather. Tropical storms may increase and so too would the consequent physical damage to coral reefs. Hurricanes Hugo and Marilyn hit the U.S. Virgin Islands National Park in 1989 and 1995 respectively and did massive damage to coral ecosystems.

Rising sea levels caused by global warming could be an additional problem for some reefs. The governments of small island nations such as the Maldives in the Indian Ocean and Kiribati and Tuvalu in the Pacific have been calling for international action to slow climate change. Their nations are based entirely on coral atolls no more than two meters above sea level; therefore, rising sea water levels could have serious impacts.

This must be the reason why, at the end of his presentation on the 1998 devastating bleaching event in Okinawa, Prof. Yossi Loya of Tel Aviv University made a this call to action: "As a coral reef society, we add our voice to the growing international concern on the issue of global climate change, and call for an effective reduction in greenhouse emissions over the next decade."

The depletion of coral reefs around the world would have dire consequences. "Apart from their beauty, coral reefs have a crucial role in shaping the ecosystems that have inhabited our tropical oceans for the last 250 million years," Prof. Hoegh-Guldberg said.

Coral reefs represent crucial sources of income and resources through their role in tourism, fishing, building materials, coastal protection and providing new drugs and biochemicals.

Globally, many people - including Filipinos - depend in part or wholly on coral reefs for their livelihood and around 15 percent of the world's population lives within 100 kilometers of coral reef ecosystems. The fisheries associated with coral reefs generate significant wealth for countries with coral reef coastlines. Annually, fisheries in coral reef ecosystems yield at least six million tons of fish catch worldwide.

Fisheries in coral reef areas, however, have beyond the mere generation of monetary wealth and are an essential source of protein for many millions of the world's poorer societies. For example, 25% of the fish catch in developing countries like the Philippines comes from coral reef associated fisheries.

Coral reefs protect coastlines from storm damage, erosion and flooding by reducing wave action approaching a coastline. "The cost of losing coral reefs would run into the hundreds of billions of dollars each year," the Greenpeace report claims. -- Henrylito D. Tacio

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