Only 1% of Japan's biggest coral reef healthy: Survey
Japan's biggest coral reef spanning 68 square kilometres has not recovered from bleaching due to rising sea temperatures, with only 1.4% percent of the lagoon in a healthy condition, according to a government study. Warmer temperatures cause corals to expel algae, which drains them of colour and could be fatal. However, corals can recover if temperature drops and algae recolonise.