JAPAN - Bleached corals are seen on a seabed near Okinawa Island on Monday. According to the Okinawa Churashima Foundation, which researches coral reefs around the Ocean Expo Park in Motobu, Okinawa Prefecture, the bleaching of coral reefs is more serious this summer than usual. In some colonies, more than half of the coral has turned white, the foundation said.
A major cause of coral bleaching is the rise of sea temperatures. The average surface temperature of the waters around Okinawa Prefecture in early August was 30.3 C, about 1 degree higher than average and about the same as the temperature recorded in 1998, when coral bleaching took place on a massive scale. Bleaching weakens the corals and leaves them more susceptible to death.