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New Disease Threatens World's Coral Reefs


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New disease threatens world's coral reefs

A new threat is surfacing that could destroy more coral reefs around the world.

The disease, called "white syndrome," has been observed affecting coral reefs in the Great Barrier Reef of Australia as well as reefs in Okinawa Prefecture.

The new threat comes on the heels of concerns about coral bleaching, which is caused by higher ocean temperatures due to global warming.

White syndrome is potentially more troublesome because coral affected by it usually die within a year of infection.

Scientists do not yet know the cause of white syndrome but believe it is some sort of infectious disease.

White syndrome has been observed in table coral found in waters about 11 meters deep off the Kerama islands, just west of the main Okinawa island.

White lines like those that mark off tracks in athletic meets were found on table coral measuring about 2 meters in diameter.

Akiyuki Irikawa, an expert on coral ecosystems who is also an official with an organization working to preserve the marine environment of the Kerama islands, conducted a study last fall off the coast of Amurojima island, part of the Kerama islands.

About 30 percent of the table coral were found to be affected by white syndrome. The white lines moved about 20 centimeters on average over the coral surface in a month's time, leading to the slow death of the coral.

While coral can recover from bleaching once water temperatures fall, there appears to be no remedy for coral affected by white syndrome because the disease exposes the skeletal structure after tearing away at coral tissue.

Around 2003, white syndrome was also found to have affected Japan's largest coral reef, in the Sekisei Lagoon between Ishigakijima island and Iriomotejima island.

A study by the Environment Ministry found white syndrome at 113 of the 123 locations surveyed.

Reports of white syndrome sightings have also come in from the Great Barrier Reef, the Caribbean and the Marshall Islands.

Diseases affecting coral have increased in variety and number over the past decade.

Abnormalities in the skeletal structure, often referred to as "coral tumors," have been reported since about 2003.

Officials of the Japanese Coral Reef Society asked the Environment Ministry on June 22 to conduct an emergency study as soon as possible.

Irikawa is one of those experts concerned about the future of coral reefs.

"In the case of the Kerama islands, if the disease spreads at the current pace, almost all of the table coral will be dead in the next 10 years," Irikawa said.

Coral is a treasure trove of marine life since it is like the tropical forest of the ocean.

However, coral is also not resilient. A change of just a few degrees in temperature can kill it, leading experts to call it the "canary of the oceans," because it foretells danger for other marine organisms.

It would not take much for a new disease like white syndrome to destroy almost all coral.

In April, the Intergovernmental Panel on Climate Change issued a report saying that almost all coral would be affected by bleaching if water temperatures rose by 1 to 2 degrees over 1990 levels and that wide swaths of coral would die if water temperatures rose by more than 2 degrees over the 1990 levels.

The United Nations Environment Program (UNEP) also issued a report last year that said about 30 percent of coral reefs had already been seriously damaged and that there was a possibility that 60 percent of coral reefs could be lost by 2030.

There are about 284,000 square kilometers of coral reef around the world. That amounts to only about 1.2 percent of the area of continental shelves.

However, coral reefs fill important roles, such as supporting the fishing and tourism industries as well as serving as a natural breakwater against high waves brought on by typhoons.

Coral reefs support diverse ecosystems, and scientists believe there are forms of marine life in coral reefs that could be used for medical purposes.

The UNEP has calculated that the economic value of coral reefs runs between $100,000 and $600,000 a year per square kilometer of reef (between 12.4 million and 74 million yen). That means the coral reef around the main Okinawa island alone is worth between 870 million yen and 5.2 billion yen.

The UNEP report released last year concluded, "There is a price to be paid for maintaining these ecosystems. The cost is, however, generally much lower than the benefit received."

Sadly, Japan may face the prospect of losing its coral reefs before it can fully realize their true value.(IHT/Asahi: June 30,2007)

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