Japanese coral breeder immunises coral against bleaching

Koji Kinjo, a Japanese coral breeder from Okinawa has succeeded in making coral almost fully immune to coral bleaching. A world first, his findings could be used to protect coral from the deadly effects of global warming. Susanne Steffen reports from Tokyo.

A Japanese coral breeder has made an important discovery that could be used to protect coral from the deadly effects of coral bleaching. (Image: WorldFish, flickr/Creative Commons)

The bad news about coral has continued this winter. Just a few months ago, experts warned that major parts of the largest and most famous reef in the world – Australia’s Great Barrier Reef – are said to be dead.

And just last month, Japan’s environment ministry reported that 70 per cent of Japan’s Sekisei reef has died from bleaching. At 400 square kilometres, it is Japan’s largest coral reef.

Last summer, 90 per cent of the reef had experienced coral bleaching, according to an investigation.

30 degrees is just too warm

The extremely high water temperatures are to blame for the mass mortality on the seafloor. The average water temperature last summer in the Sekisei reef was 30.1 degrees Celsius, one or two degrees higher than average water temperatures in the region.

Corals react to warm water by repelling the microorganisms that supply them with nutrients, which results in the corals losing their colour and turning white.

Bleaching itself is not an automatic death sentence for coral, but if water temperatures fail to normalise fast enough, the coral eventually die from a lack of nutrients.

As ocean temperatures around the world are rising in the face of climate change, experts see a very bleak future for coral reefs.

According to an international study led by the Atlantic Oceanographic and Meteorological Laboratory, 99 per cent of all reefs may have to live with annual bleaching by the end of this century.

Survival of the fittest

Hope for coral reefs comes in the shape of a Japanese coral breeder from the subtropical Okinawa in the coral-rich southern part of the country.

Koji Kinjo, who has over 20 years experience in breeding coral, made an astounding discovery seven years ago when he moved his corals from a deeper part of one of his breeding tanks to a shallower place to better show school children how corals spawn.

Most of the corals bleached under the extreme sun exposure in the warmer, shallower waters. Many died, but a few recovered.

Kinjo took the surviving corals and placed them in an even shallower place. Again, many died. He then took those that had survived the harsh conditions and exposed them to even more heat and sunlight.

After four years, Kinjo’s corals had become so accustomed to the new environmental conditions that they didn’t bleach even under intense sun exposure.

These are very likely the world’s first corals that appear to be immune to the deadly bleaching.

Hope for a new breed

“It’s a wonder. I’ve never seen anything like it before,” celebrated the 47-year-old in a recent interview with the public broadcaster NHK.

First tests in an endangered reef have already shown that Kinjo’s corals are also able to survive under real-life conditions in the ocean.

It’s still unclear just how the corals adapted to the warmer water temperatures. But Japanese marine biologists now hope to save the country’s reefs with the help of Kinjo’s new breed of corals.

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