DIRECT HUMAN IMPACTS ON CORAL REEFS: POLLUTION, OVERFISHING AND CYANIDE AND DYNAMITE FISHING

REEFS AND POLLUTION

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Demand for reef fish
as pets, one of the main causes
of reef damage
Reefs have been damaged to varying degrees by pollution from factories, runoff from farms, fertilizers, and pesticides. Roberto Iglesias, a biologist from UNAM, a university in Mexico, and author a study on pollution in the sea in Science magazine, told Reuters, “The net effect of pollution maybe as bad or maybe worse than the effect of global warming.” Coral reefs near Cancun in Mexico that Iglesias has studied have sickly brown spots and are being engulfed by algae that feeds on sewage flowing from the resort.

Corals can flourish is surprisingly murky waters, as long tides or currents periodically sweep away sediments. Nutrients are what hurt them the most. High levels of nitrogen from sources such as fertilizer provide food for free-living algae which explode in bloom and smother other sea creatures.

Corals deal with stresses like silt and pollution by secreting mucous proteins on their outer tissues, which often attracts viruses, bacteria and fungus that feed on the mucus and sometimes even breed there.

Many reefs have been seriously overfished. Even traditional fishing methods can destroy coral reefs. A study in Fiji by scientists from the University of Newcastle found that fishing with spears and hooks and lines killed off predators of the crown of thorns starfish, allowing them to multiply and seriously damage the reef.

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Great Barrier Reef
Overfishing have made Queen conch, spiny lobster, whelk, red snapper and Nassau grouper commercially extinct in many places. Once abundant jewfish (grouper) have all but disappeared in the Caribbean. Overfishing also hurt stocks of fish that eat coral-damaging algae.

Websites and Resources: National Oceanic and Atmospheric Administration noaa.gov/ocean ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Ocean World oceanworld.tamu.edu ; Woods Hole Oceanographic Institute whoi.edu ; Cousteau Society cousteau.org ; Montery Bay Aquarium montereybayaquarium.org

Websites and Resources on Fish and Marine Life: MarineBio marinebio.org/oceans/creatures ; Census of Marine Life coml.org/image-gallery ; Marine Life Images marinelifeimages.com/photostore/index ; Marine Species Gallery scuba-equipment-usa.com/marine

Websites and Resources on Coral Reefs: Coral Reef Information System (NOAA) coris.noaa.gov ; International Coral Reef Initiative icriforum.org ; Wikipedia article Wikipedia ; Coral Reef Alliance coral.org ; Global Coral reef Alliance globalcoral.org ; Coral Reef Pictures squidoo.com/coral-reef-pictures ; The Global Coral Reef Monitoring Network; the International Coral Reef Action Network.

Human Threats to Coral Reefs

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diseased coral
Reefs are threatened 1) global warming; 2) pollution caused sewage and fertilizer; 3) coral mining; 4) industrial and agricultural run off; 5) sediment from deforestation; 6) dredging of harbors and channels; 6) the use of poisons and dynamite by fishermen; 7) commercial fishing; 8) sport fishing, scuba diving and tourism; 9) sediments from coastal development; and 10) the commercial exploitation of fish, corals, giant clams and other species.

If too many grazing fish are caught, algae grows unchecked and the coral polyps are deprived of sunlight. Careless thrown anchors and misplaced hands or fins day after day by scuba divers and snorkelers can also seriously damage fragile corals. Once destroyed by a carelessly tossed anchor, a reef needs 20 to 30 years to repair the damage.

Sediments from erosion block life-sustaining sunlight, choke the pores of sponges and causes corals to weaken and be overpowered by algae. Nitrogen and phosphorous from fertilizer causes suffocating algae blooms and increases plankton growth which can lead to population explosions of coral-damaging star fish. In some places conditions are so bad that the emphasis has shifted from documenting damage to accessing if and how the reef might be restored.

Coral Trade and Reef Diseases

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bleached coral
Pink and red corals are among the most valued corals for jewelry. A singles necklace made with them can sell or $25,000, with a kilogram of polished coral costing up to twice that. In Japan and other places red and pink coral is harvested in water about 100 meters deep. In Japan, the red and pink coral industry employs about 3,000 people and is worth about $100 million a year. It also employs large numbers of people in North Africa, where it’s the basis of a cottage industry.

Harvests of red and pink coral have declined by 85 percent since 1980. In March 2010,The United Nations Convention on International Trade on Endangered Species (CITES), the United Nations wildlife trade body, proposed controlling the trade of red and pink coral. The measure, which was sharply opposed by Japan, targeted seven species, one in the Mediterranean and six in waters off Japan and Taiwan, along with 24 “lookalike” species to prevent accidental harvesting. But the proposal was rejected out of concerns over job losses and economic damage.

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Bleached coral
Reef diseases caused by natural and manmade forces include white-band disease, a slow-moving infection that causes coral tissues to peel off their skeleton and is believed to be caused by a rod-shaped bacterium; yellow-ban disease, characterized by algae loss and yellow patches on the reef; and black-band disease, an infection caused by sulphur-oxidizing and sulphur-reducing bacteria that marches across patches of coral in black band, leaving behind bleached coral.

Other reef diseases found in the Caribbean include patch necrosis, white pox, white plague and rapid wasting disease. In some places unusually arm waters lead to a proliferation of coral-eating spiral shells.

Demand for Reef Fish

The international aquarium fish trade is worth up to $1 billion a year. Up to 20 million tropical saltwater fish are sold in the United States every year. Demand for tropical fish as pets increased markedly after the success the animated film Finding Nemo . The fish are stored in plastic bags in warehouses and flown from country to country. Many of the fish that are captured are very sensitive and many---perhaps most---die before they ever reach an aquarium. Those that survive endure days or weeks confined to plastic bags.

There is a strong demand for large, living reef fish for Chinese banquets. Customers at the Fook lam Moon restaurant in Hong Kong's Tsim Sha Tsuo pay $369 for a large fresh wrasse plucked from a restaurant tank.

In the West people have traditionally eaten coastal and pelagic fish such as cod and tuna while Asians have eaten these fish plus reef fish such as grouper and snapper, which live in reefs and can't easily be caught with nets. Asians also believe that a wild fish that is alive until it is eaten is superior in taste and texture to a fish that has been raised on a farms or frozen. Asians will up pay to ten times more for fresh fish that they see alive before the eat it.

The Asian economic boom in the 1980s and 1990s created a large demand for live fish. Suddenly, a delicacy once reserved for royalty and the upper classes became affordable to the masses at local restaurants. Cyanide fishing and air freight business expanded to meet the demand. The live fish trade grew steadily and by 1995, it was $1 billion, 25,000-ton a year industry.

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Seattle aquarium tank

Cyanide Fishing

Fishermen in some parts of the world, particularly the Philippines and Indonesia, catch fish by squirting cyanide from plastic bottles into crevasses in the reef. The cyanide temporarily stuns the fish so they can be easily captured by hand or with small nets, often using a crowbar to pry apart the reef where the fish hide. Fisherman in the Philippines cover their faces like terrorist for protection from jellyfish stings and can stay underwater for long periods of time thanks to hoses attached to an air compressor known as a "hookah." The poison initially does not normally harm the fish but it hurts the living coral. Fishermen also use bleach and other chemicals to get fish.

Sodium cyanide capsules are cheap and easy to obtain in Asia. All one has to do create cyanide is crush a couple of these capsules and put the powder into a spray bottle of water . Cyanide fishermen then dive around a coral reef, find they fish they want and squirt the toxic mixture in it face or skirt it in an area of the reef teeming with fish. Fishermen often store the cyanide in cans on the ocean floor to escape detection by authorities.

Long-lasting cyanide kills fish, coral polyps and other forms sea life. The cyanide kills the algae of the reef on which fish feed. Then the coral itself starts to die. Cyanide fishing is also harmful to fisherman who handle the cyanide and have to search in deeper and deeper water to find fish. Recalling his fifth experience with the bends, one Filipino cyanide fishermen told National Geographic, "I went down 70 meters [230 feet] and worked for about two hours. I came straight up. A minute after I got in the boat, I went into shock." He has been paralyzed from the waist down ever since. One in ten cyanide divers either dies or is disabled.

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Coral drilling

Cyanide Fishing Trade

The practice of cyanide fishing began in the 1960s to supply tropical fish for the international aquarium trade. Since the early 1980s many of the fish caught using the methods have gone to supply restaurants in Hong Kong, Singapore and increasingly mainland China that offer reef fish pulled from a tank. The practice reached in peak in the early 1990s when 330,000 pounds of poison was placed on 33 million coral heads a year.

Small fish like clownfish and damselfish are captured for the tropical fish trade and large fish like grouper and rock cod are caught for restaurants. Half the fish die while being transported. While cyanide fishing is illegal, the selling of fish caught with cyanide is not. Fish like flame gobies that are sold for around 50 cents a piece by the fishermen that catch them fetch up to $50 a piece retail.

Fish caught using cyanide often survive long enough to be sold at pet shops in the United States, Europe and elsewhere but often die within a couple of months after they brought home. Cyanide poisoning often acts slowly through the digestive system, attacking the liver and eating away at digestive system and respiratory system.

Sometimes large ships from Taiwan and Hong Kong provide local fishermen with "hookah” air compressors and cyanide needed to catch fish. These ships are blamed for the disappearance of large fish from reefs in Thailand, the Philippines and Indonesia.

Dynamite Fishing

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Coral cutting
In some places people catch fish by setting off an explosive charge in the water which kills or stuns fish with its percussive blast. The fishermen then scoop up the fish when they float to the surface. The fish are generally caught not to feed their families but sell for profit.

Dynamite charges are often used to create the explosions. The dynamite blows off huge chunks of reef and kills plankton, larvae, eggs, fingerlings, coral and other life forms. Blast fishing is also done with a mixture of fertilizer and diesel, an explosive mix favored by unsophisticated terrorists.

Dynamite fishing became common place in the 1970s. Although the practice is illegal most everywhere now, it is still used in the southwestern Pacific where laws are difficult to enforce in the vast sea.

Combating Cyanide and Dynamite Fishing

Efforts are being made to educate fishermen that although cyanide and dynamite fishing may increase catches in the short run they destroy the goose that laid the golden egg in the long run. This message is delivered to children in school with puppet shows.

Environmental groups are encouraging fishermen to use traditional fishing methods and to create a sense that the reefs are a resource that needs to be preserved. Villagers are encouraged establish offshore fish farms, seaweed farms and to set up "fish-aggregation devices"---floating platforms anchored in the water that attract algae and fish.

Tests for cyanide have been developed. A campaign has been launched to screen fish for the presence of cyanide and ban the import of fish caught in areas where cyanide fishing is used.

Some places have introduced punishments such as prison sentences and heavy fines and stepped up enforcement. Not everyone is happy about the efforts. In some place fish bombers threaten authorities with automatic weapons and the same bombs they use to blow up fish.

Efforts to Help Endangered Coral

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Coral protected in Marine park Motu Motiro Hiva
Measures taken by human to repair reefs include using metal rods to hold up broken pieces of coral in place, and clearing away debris, and sediment. Researchers are experimenting with transplanting coral and introducing new species to new areas.

Reefs can revive themselves in as little as five years as was the case with a reef off Banda Indonesia that was completely destroyed by lava from an eruption.

Ken Nedimyer, a Florida-based research scientist who got his start in the aquarium business, has a nursery with a variety of coral strain, growing under different conditions. He is experimenting with taking bits of live coral and glueing them to different surfaces. He told the New York Times, “We tried a lot of epoxy. We found kinds that stick to wet suits, to hair, to cameras” They finally settled in an epoxy glue used by taxidermists which hold firm in water and is white so it doesn’t look bad.”

David Lackland of the Mote marine Laboratory in Florida

Coral, Warm Water and Global Warming

Image Source: National Oceanic and Atmospheric Administration (NOAA) noaa.gov/ocean

Text Sources: Mostly National Geographic articles. Also the New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

Last updated March 2011


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