An environmentalist in the Marshall Islands says some coral reefs in the north Pacific are struggling to survive as coral bleaching becomes more widespread in the region.
Bleaching has been linked to greenhouse gas emissions that are causing ocean temperatures to rise.
The University of Hawaii's coral reef manager in Majuro, Karl Fellenius, says coral reefs in the Marshall Islands had not been vulnerable to significant bleaching until this year.
Dr Fellenuis says it could get worse if gas emissions aren't brought under control.
"This is the first large-scale bleaching event that the Marshall Islands has seen and in fact it is associated with a much larger event in the region that has seen bleaching since the summer from northern Marianas through to Kiribati and up to Hawaii."
Karl Fellenius says coral bleaches in response to extreme temperatures.