Black death destroying Green Island coral reefs

TAITUNG, Taiwan -- Green Island, only a little over 16 nautical miles southeast of Taitung on east Taiwan, is one of the world's best spots for scuba diving and snorkeling.

The island, which used to be a concentration camp for political prisoners, has amazingly beautiful and thriving coral reefs, which may be destroyed by atramentous necrosis, or black death, in five to six years.

That is a prognosis offered by Taiwan's leading marine biologist, who conducted research on the threat of black death on the coral reefs around Green Island.

The coral disease is named black death because it typically presents itself as blackened lesions that spread within days across an infected surface of colonies.

Little is known of this disease though it does appear to favor corals of the species Montipora aequituberculae and temperature appeared to be a key variable associated with the outbreak.

At least five other species from three different genera are found to be affected, too.

Chen Jhao-lun, a senior research fellow at the Academia Sinica who has studied the coral reefs, describes the affected colonies as being covered slowly with a piece of black cloth.

“As this black sponge which multiplies itself covers the colonies, it shuts off sunlight to stop photosynthesis by coral polyps,” Chen is quoted as telling the Apple Daily.

An Apple Daily reporter covered Chen's research.

Polyps die as a result. Nor corals could be formed.

The marine biologist has found dead colonies on inshore reefs, almost all around the island. But he believes black death is still in its infancy. The danger of the death of coral reefs is not imminent.

Last year, Chen says, only four colonies off Dabaisha or Great White Sand were infected with black death. In April, when he last dived to investigate, he discovered 24 colonies affected, an increase of 20 or six times as much.

Should nothing be done to stem the spread of black death, Great White Sand near the southernmost tip of Green Island would have only dead colonies in five to six years, Chen predicts.

When coral reefs are dead, there will be no beautiful coral fish. No tourists will come to visit the island.

Similarly affected are the reefs off Caikou on the northern shore of Green Island. “We have found fewer and fewer beautiful coral reef fishes in waters three to six yards deep at Caikou,” says Yu Chih-huang, a Green Island diving coach.

Molecular studies of the black death lesions have so far failed to identify a likely microbial pathogen, Chen says. It appears that the black layer that spreads rapidly across the infected colony is an opportunistic second effect rather than the causative agent of the coral mortality.

One hypothesis Chen offers is overfishing, which causes an imbalance in the coral reef food chain. Manmade pollution of the sea waters may cause black death to spread.

Hundreds of thousands of tourists visit Green Island a year. Their effluence flushed out of the island totals 1,500 tons a day.

No sewage treatment project has been prepared for Green Island, however. Land can't be procured for a treatment plant.

Source: http://www.chinapost.com.tw/taiwan/local/offshore-islands/2009/06/01/210351/Black-death.htm

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