Chemical may deter starfish from devouring endangered coral reefs

December 16, 2000

Click here for abstract 1 and here for abstract 2:

HONOLULU, Dec. 17 - Researchers have discovered a chemical in sea urchins that might be used to lure starfish away from coral reefs, an endangered ecosystem they are devouring at an alarming rate. The finding was presented here today during the 2000 International Chemical Congress of Pacific Basin Societies.

The weeklong scientific meeting, held once every five years, is hosted by the American Chemical Society, in conjunction with its counterparts in Australia, Canada, Japan and New Zealand.

The poisonous crown-of-thorns starfish, which feasts on coral and whose population is believed to be expanding, is a major source of destruction of valued habitats in the tropical zones of the Indian and Pacific oceans, including Hawaii. The problem is acute in Japan, where extensive, costly efforts to control the creature have met with little success.

Home to a variety of organisms that are a potential source of life-saving medicines, coral reefs have been called the rainforests of the sea. These rich ecosystems are rapidly disappearing. An estimated 27 percent of the world's coral reefs have already been destroyed, according to the Global Coral Reef Monitoring Network, an organization established to assess and improve reef conditions. Unless better management is established, 40 percent of the world's reefs will be lost by 2010, the network predicts. Starfish are expected to be a significant factor in this decline.

Researchers at Nagoya University in Nagoya, Japan, recently discovered that sea urchins contain a chemical that appears to attract starfish. After laboratory analysis, they isolated the active chemicals from the urchin and found they are two unsaturated fatty acids: arachidonic acid and a-linolenic acid.

While only a small number of starfish were captured during an initial trial of the attractant, the results are promising because they represent proof of principle, says Daisuke Uemura, Ph.D., the study's lead researcher and a chemistry professor at the university.

"Although we can't save all of the coral reefs in the world from destruction, our research is useful for saving some of them," says Uemura.

Most attempts to control the starfish population have been unsuccessful. Poisoning harms other creatures that share their habitat. Cutting them up is compromised by the ability of starfish to regenerate whole organisms from severed parts. Other methods include catching the creatures with a harpoon and isolating the adults from coral with underwater fences. Methods under consideration include the introduction of diseases and predators that are specific to the starfish.

No one is certain why outbreaks of starfish appear to have increased in recent years. One theory suggests that their populations bloom several years after a large typhoon with high rainfall, which produces abundant sediments. These sediments are thought to contain nutrients that contribute to plankton blooms, which serve as food for young starfish. Other theories point to the destruction of their major predators and the effects of pollution.

Besides starfish, many other forces play a major role in the destruction of the reefs. These include overfishing, pollution, typhoons and global warming. In Hawaii, where most of the coral reefs in the United States are found, coral is being decimated by tourists, particularly snorkelers.

More than 8,000 research papers will be presented during this year's International Chemical Congress, which is sponsored jointly by the American Chemical Society, the Chemical Society of Japan, the Canadian Society of Chemistry, the Royal Australian Chemical Institute and the New Zealand Institute of Chemistry.
The paper on this research, ORGN 850, will be presented at 8:40 a.m., Sunday, Dec. 17, at the Hilton Hawaiian Village, Coral Ballroom I, Mid-Pacific Conference Center, during the symposium, "Natural Products of Chemistry: Biological Activity and Synthesis." In addition, a poster on this research, ORGN 1277, will be presented at 9:00 a.m., Monday, Dec. 18, at the Hilton Hawaiian Village, Coral Ballroom III, Mid-Pacific Conference Center, during the same symposium.

Daisuke Uemura is a professor in the department of chemistry at Nagoya University in Nagoya, Japan.

American Chemical Society

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