Coral Reef Destruction

Canada and the World

Current Events with a Canadian Perspective

Last update

29 August 2011

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Destruction of Coral Reefs

Human activity is taking a toll on a vital marine ecosystem, one that protects coastlines and

provides a habitat for a rich variety of marine life

In her 2009 book Sea Sick, Alanna Mitchell writes: “The worldwide decay of coral reefs – caused by the pollution from land, too much fishing, nasty practices to capture wild fish for the aquarium trade, and waters that are too hot because of global climate change – has already started to take its toll.”

NASA

World coral reef locations.

Coral Reefs a Rich Source of Marine Life

The Coral Reef Alliance points out that “Although they cover only two-tenths of one percent of the ocean floor, these complex tropical ecosystems rival the rainforests in terms of biodiversity, supporting nearly a quarter of all marine species.”

Writing in The Independent (February 24, 2010) Steve Connor says that coral reefs “provide food for about 500 million people around the world.”

Carbon Dioxide Threatens Reefs

According to the Coral Reef Alliance, the burning of fossil fuels releases carbon dioxide and billions of tonnes have been absorbed by the oceans.

This has changed the chemistry of sea water making it more acidic. As a result, coral and shell formations are impaired; when the shells stop forming the reef crumbles quickly.

Dr. Jacob Silverman of the Carnegie Institution of Science in Washington has studied this problem and has used a mathematical model to see what rising acidity will do to 9,000 coral reefs around the world.

He told a February 2010 meeting of the American Association for the Advancement of Science in San Diego and quoted in The Telegraph (February 24, 2010) that, “A global map produced on the basis of these calculations shows that all coral reefs are expected to stop their growth and start to disintegrate when atmosphere CO2 reaches 560 parts per million – double its pre-industrial level – which is expected by the end of the 21st-century.”

Coral Bombing Destroys Habitat and Fish

Among the reefs of the Philippines, Indonesia, and Micronesia, people are using dynamite to catch fish. Blast-fishers throw pop-bottle grenades into reef areas.

The explosion kills everything nearby (left) and the “fishers” retrieve the dead fish that float to the surface, mostly for local consumption. The explosion also rips apart the coral. The structures made by these living corals are very slow growing; some can take centuries to form.

According to Kate McClellan with the Encyclopedia of the Earth, “The use of blast devices is economically efficient – a single bomb costs about 1-2 U.S. dollars to build, while the resulting catch is worth between 15 and 40 U.S. dollars.”

Blast fishing has been made illegal in the Philippines, Malaysia and other areas but it still goes on, because it’s difficult to police long coastlines.

Cyanide Fishing for Aquariums

Cyanide fishing first appeared in the Philippines in the early 1960s and, writes Andy Bruckner of the National Oceanic and Atmospheric Administration, “Cyanide fisheries expanded to the live reef food fisheries in the 1970s and over the next two decades it spread throughout Southeast Asia and into the Pacific islands. Cyanide fishing has been confirmed in 15 countries.”

Divers use squeeze-bottles to squirt a solution of sodium cyanide into coral where reef fish hide. The idea is to temporarily stun the fish, net them, and put them into tanks for transport to aquariums for sale.

Unfortunately, the cyanide kills the coral.

Coral Reefs Disappearing

With all of these impacts it’s not surprising that coral reefs are in trouble.

The Coral Reef Alliance says that with 11 percent of reefs already destroyed “Scientists predict that another 32 percent may be lost in the next thirty years if human threats are not reduced.”

Dr. Silverman of the Carnegie Institution of Science says “…these ecosystems, which harbour the highest diversity of marine life in the oceans, may be severely reduced within less than 100 years.”

Image credit

Public Library of Science

Sources

“Sea Sick.” Alanna Mitchell, McClelland & Stewart, Toronto, 2009.

“Coral Reefs in Danger of Being Destroyed.” Steve Connor, The Independent, February 24, 2010.

“AAAS: Coral Reefs could Disappear by the End of the Century.” Richard Alleyne, The Telegraph, February 24, 2010.

“Coral Degradation through Destructive Fishing Practices.” Kate McClellan, Encyclopedia of the Earth, August 24, 2008.

“Cyanide Fishing Makes a Comeback.” Andy Bruckner, National Oceanic and Atmospheric Administration, August 2008.

“Coral Grief: Warming Climate Threatens Reef Destruction.” David Biello, Scientific American, July 10, 2008

MANY OTHER

THREATS TO CORAL

The Coral Reef Alliance lists many other activities that destroy coral reefs:

Sewage dumped untreated into oceans and fertilizer run off cause massive increases in algae, which blocks sunlight from coral reefs causing them to die;

Construction, mining, farming, and logging can all lead to erosion. Particles of soil and dust are carried into the ocean by rivers and can settle on coral reefs, smothering them;

Mangrove forests that protect coral are being destroyed to make way for prawn farming and beach development;

Coral is sometimes taken for building materials and to make trinkets for tourists; and,

The increased ultraviolet radiation from the Sun that comes from thinning of the ozone layer around the planet may contribute to coral reef weakening.

“Is a coral species, whose population was reduced from maybe a billion to 300 million or even a few hundred thousand, really threatened by extinction? Personally, I very much doubt it. But I think the ecological function of many reef-building corals is threatened by quite drastic losses in their abundances.”

Marine biologist John Bruno of the University of North Carolina, quoted in Scientific American, July 2008

Coral reefs are home to roughly a quarter of all known marine life including fish and algae.