Scientists to 're-plant' Japan's largest reef

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Scientists in Japan are undertaking a project to restore the country s biggest coral reef.

Thousands of juvenile corals are to be planted in the Sekisei Lagoon, Okinawa, which has suffered major bleaching due to rising sea temperatures.

No projects in the world have ever restored a coral reef artificially, Mineo Okamoto, associate professor at the Tokyo University of Marine Science and Technology, told Cosmos. Most projects are instead focused on attempting to improve conditions, or transplanting corals to a new location.

As part of the project, six thousand juvenile corals, now 18 months old, have been grown on small ceramic beads. The beads, 4cm in diameter, have a ~leg by which they can be attached to the sea bed.

The team of scientists, working in conjunction with Japan's environment ministry, will plant the corals over an area covering 600 square metres within the Sekisei Lagoon in December.

This is the projects second attempt. In 2006, 5,300 juvenile corals were planted, of which only one-third survived. Many were damaged by the collapse of surrounding dead coral, which were disturbed by typhoons.

We have learned lessons from the previous planting regarding what are the best places to plant and other conditions for survival. We'll make a fresh try, said Okamoto.

The coral populations in Sekisei Lagoon have fallen victim to rising sea temperatures, notably in the summers of 1998 and 2001, which has resulted in major bleaching. Coral-eating starfish have also contributed to what has been an 80% reduction of coral numbers within the lagoon over the last 20 years.

The project aims to restore the lagoon in some 10 years. If successful, the team hope that the method can be replicated elsewhere, with preparations already underway for a similar project in Indonesia.