Starfish threaten Shirahama coral reefs

OSAKA (Kyodo) The coral reefs of Shirahama, Wakayama Prefecture, are being devoured by an explosive increase in poisonous starfish, and only five volunteer divers armed with tongs are combating them to save the rich marine environment.

Seeing stars: Katsuyuki Nakaya (left), a dive shop operator who heads a local environmental group, shows off crown-of-thorns starfish plucked recently from the coral reefs off Shirahama, Wakayama Prefecture. KYODO PHOTO

The crown-of-thorns starfish ("oni-hitode") originally lived in subtropical seas. But after the 1990s, they started appearing off Kyushu and Shikoku as well as Wakayama, apparently because of global warming and eutrophication caused by the development of coastal areas of Japan.

Unless drastic eradication efforts are mounted, the coral reefs of Shirahama, a popular tourist spot on the Kii Peninsula, could be decimated within one or two years, experts warn.

"If we keep removing (the starfish) in limited areas on a regular basis, there should be some effect," said Katsuyuki Nakaya, 53, who runs a shop catering to divers and chairs an environmentalist group based in the city of Wakayama.

The five volunteer divers, including Nakaya, must wear protective gear when prying the starfish off the coral because of the creatures' poisonous thorns.

Kushimoto, another Kii port east of Shirahama, was hit by a massive onslaught from the pest from 2004 through 2007.

The municipal government of Kushimoto, also a popular diving and tourist spot, gave subsidies to divers who helped remove around 60,000 of the starfish over the four-year period. This apparently resulted in only 3,000 crown-of-thorns starfish sightings in 2008.

Nakaya and the other four divers are shouldering the entire cost of their starfish-removal activities, including boat fuel. They have asked the Wakayama Prefectural Government and other bodies to help.

"Coral reefs have been destroyed by humans. Humans should take responsibility and protect (the environment)," Nakaya said.

Tatsuo Motokawa, a professor at Tokyo Institute of Technology, said corals live in shallows with temperatures 18 or higher near over 80 countries.

The area accounts for only 0.1 percent of the world's seas, but about one-third of all ocean fish live among them, the reason coral is dubbed the "oasis of the sea."

However, only one-third of coral reefs are believed to be healthy.