Scubaism

The Sekisei Lagoon, one of the nation’s largest coral reefs, spans about 15 kilometers north-south and about 20 km east-west, between Ishigakijima and Iriomotejima islands. It is the centerpiece of a government rejuvenation project.

In one initiative led by the Environment Ministry, young coral heads were transplanted into the bed of the lagoon, off Kuroshima island, in February 2006. Underwater monitoring in June found the coral heads were steadily growing, giving some cause for hope. The coral had grown to more than 10 centimeters in diameter.

In 1997 and 1998, the rise in seawater temperatures caused widespread bleaching of coral around the globe. In Okinawa, flooding caused large amounts of red soil to be deposited onto the seabed–causing more damage. The red soil covered areas where the coral larvae implant naturally, making it difficult for new coral to be produced. Further complicating the issue has been an increase in numbers of crown-of-thorns starfish, the coral’s natural predator.

Under the government project, about 240,000 small ceramic implantation modules, used to anchor the coral, have been placed in the Sekisei Lagoon over the past several years. So far, about 6,000 of the modules, on which coral has successfully been implanted, have been removed and transplanted to other parts of the reef, around Kuroshima island, for example.

Mineo Okamoto, associate professor of ocean instrumentation at the Tokyo University of Marine Science and Technology, is pleased with the progress so far. “If nothing was done, the coral on the southern side of the Sekisei Lagoon could have been devastated,” said Okamoto, who is cooperating with researchers in the government project. “The results have given us hope.”