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December 2008

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WORLD TREASURE

Green Island: The Vitality and Crisis of the Tiny Heaven

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The Green Island lighthouseSchools of bright fishes around “The Big Mushroom”

Green Island, an islet located 18 nautical miles (33.34 km) off the east coast of Taiwan, has a population of about 3,000 and a surface area of 15.09 km2. It is one of the migration bases of the Austronesian peoples, and was located in the international fairways during the Great Navigation Era. The indigenous groups here include the Amis and Tao, who have gradually moved away after the immigration of people from Small Ryukyus since early 19th century. Due to the distance from Taiwan, residents here have developed a unique living mode. The 19 old houses of Youzihu tribal settlements is the most ancient and soundly preserved traditional architecture of the island.

Also called the “Fire-burned Island,” Green Island was formed by volcanic eruptions and is surrounded by apron coral reefs. It is blessed with unique geological landscapes. Mt. Amei, Mt. Niouzih, Mt. Fire-burned are left as evidence of five periods of volcanic activities, while the Haishen platform and the volcanic skeletons near Youzihu could both be the eruption center from the 4th period. Other landscapes include the columnar joints on the Haishen platform, the fault of the Fanchuanbi area, and finally the noted Sunrise Hot Springs, which is one of the three biggest ocean bed hot springs in the world.

An Island of Natural Wonders
According to a statistics done in 1991, there were 215 species of corals in the surrounding sea areas of Green Island; scholars estimate the actual number could reach 300 to 350. It is just a wonder to have such a big number around this small island (the Great Barrier Reef has 400).

“Green Island has such a beautiful coral world because it is located in the north brink of the Coral Triangle, with clear water and the warm Kuroshio passing by,” explained Dr. Chaolun Allen Chen of the Biodiversity Research Center, Academia Sinica.

There are two primary types of coral colonies in Green Island: the soft coral colonies located between the lighthouse on the southwestern coast and the Great Whitesand, and the rock corals found along the northern and eastern coast from Jhong-liao to Sunrise Hot Springs. The soft corals here include Xeniidae, Cespitularia taeniata, and Nephtheidae; the exuberance is rarely seen even across the world. Why these two distinct coral colonies would take up their own territories without merging remains a mystery; strong currents and typhoons are two possibilities.

The coral colonies are like a marine ecology classroom, and the performance of fishes is as remarkable. A preliminary survey shows there are 385, mostly tropical western Pacific species, including Pomacentridae, Labridae, and Chaetodontidae. Some scholars estimate the actual number is two times big. However, the fishery activities have greatly decreased it.

One noteworthy coral here is a Porites sp. nicknamed “Big Mushroom,” with a 12 m height, a 31 m circumference, and an age of 1200 years. It is the biggest and most intact Porites sp. in the world, and is actually an easily reachable world-class scuba diving spot.

“‘Big Mushroom’ has been struck twice by submarines and thus has two indented holes. The holes are covered by other creatures, which compete with the living coral for survival and have led to its continuous decay,” said Dr. Chen gravely.

The yearly 400,000 tourists have
also brought huge shocks to the marine ecology. Without the sewerage system, the waste water goes into the ocean directly, leading to an unimaginably terrible pollution.

Acropora of Green Island and many Holanthias“Big Mushroom” has been struck twice by submarines; the holes are now covered by many soft coralsSea fan corals (Gorgonia spp.) beside “Big Mushroom”

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  • upper left: The Green Island lighthouse / by Chi-hsue Wu
  • upper rught: Schools of bright fishes around “The Big Mushroom” / provided by Allen Chen
  • lower left: Acropora of Green Island and many Holanthias / provided by Allen Chen
  • lower center: Big Mushroom” has been struck twice by submarines; the holes are now covered by many soft corals / provided by Allen Chen
  • lower right: Sea fan corals (Gorgonia spp.) beside “Big Mushroom” / provided by Allen Chen

Interview & Text / Wan-ching Lai
Translation / James Chang
Special thanks to / Dr. Allen Chen, associate research fellow of Biodiversity Research Center, Academia Sinica

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