"HONOLULU — Warmer-than-normal ocean temperatures around Hawaii this year will likely lead to the worst coral bleaching the islands have ever seen, scientists said Friday.

Many corals are only just recovering from last year's bleaching, which occurs when warm waters prompt coral to expel the algae they rely on for food, said Ruth Gates, the director of the Hawaii Institute of Marine Biology. The phenomenon is called bleaching because coral lose their color when they push out algae.

The island chain experienced a mass bleaching event in 1996, and another one last year. This year, ocean temperatures around Hawaii are about 3 to 6 degrees Fahrenheit warmer than normal, said Chris Brenchley, meteorologist for the National Weather Service in Honolulu."

Audrey McAvoy reports for the Associated Press September 12, 2015. [2]