75% of Japan's biggest coral reef died from bleaching

Almost three-quarters of Japans biggest coral reef has died, according to a report that blames its demise on rising sea temperatures caused by global warming.

The Japanese Environment Ministry in its report said that 70 per cent of the Sekisei lagoon in Okinawa had been killed by a phenomenon known as bleaching, the Guardian reported on Thursday.

Bleaching occurs when unusually warm water causes coral to expel the algae living in their tissues, causing the coral to turn completely white. Unless water temperatures quickly return to normal, the coral eventually dies from lack of nutrition.

The plight of the reef has become "extremely serious" in recent years, according to the ministry, whose survey of 35 locations in the lagoon last November and December found that 70.1 per cent of the coral had died.

The dead coral has now turned dark brown and is now covered with algae.

The ministry report follows warnings by the Coral Reef Watch programme at the US National Oceanic and Atmospheric Administration that global coral bleaching could become the "new normal" due to warming oceans, the Guardian said.

Experts said that bleaching had spread to about 90 per cent of the Sekisei reef, a popular diving spot that covers 400 sq.km.

A similar survey conducted in September and October last year found that just over 56 per cent of the reef had died, indicating that bleaching has spread rapidly in the following months.

--IANS

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