Scientists from the US and Marshall Islands say record warming of ocean water in the north Pacific has caused unprecedented coral bleaching from Hawaii to the Northern Mariana Islands.
The Marshall Islands coastal management extension agent in Majuro, Dr Karl Fellenius, says the worst coral bleaching event ever recorded for the Marshall Islands has been occurring since mid-September.
The Marianas Variety reports that major bleaching was also seen in Guam and the Commonwealth of the Northern Marianas Islands, the northwestern Hawaiian Islands and Kiribati.
For the main Hawaiian Islands, it was the first sighting of widespread bleaching.
Bleaching's emergence as a global problem has been linked to greenhouse gas emissions that are causing temperatures to rise.
Dr Fellenius says corals in the Marshall Islands as deep as 40 metres have been damaged or killed by the high ocean temperatures the past several months.