Half Of Hawaii's Coral Reefs Hit By Bleaching After 2014-15 Heatwaves


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

Bleached coral in the shallow waters of Lisianski, one of the worst affected areas of the 2014-2015 bleaching event. NOAA

It looks like Hawaii’s beautiful coral reefs are on the same depressing path as the Great Barrier Reef down under. Research has found that the health of the coral reefs around Papahānaumokuākea Marine National Monument crashed after the unprecedented heat waves of 2014 and 2015.

Back in September, a study published in the journal PLOS ONE found over 90 percent of the coral in the shallow waters around the island of Lisianski had suffered bleaching due to heat stress.


Along with these findings, the Associated Press reports that other NOAA-affiliated scientists recently found a further 56 percent of the Big Island's coral was bleached, along with 44 percent of West Maui's, and 32 percent around Oahu. The scientists took these findings to lawmakers in Honolulu last week in an attempt to advise policy on how to address the problem.

Coral get their stunning coloring from the microalgae that live symbiotically with them. If the coral becomes stressed due to environmental stressors such as extreme heat, the photosynthetic algae abandon the coral’s tissues, leaving them without the nutrients they need to live and draining them of color, hence “coral bleaching”. While bleaching is not an immediate death sentence for the corals, it can be difficult to recover from and often leads to them perishing and dying. Besides anything else, it's a fairly clear red flag that something is not right.

In 2016, the world's reefs experienced their third global bleaching event, with bleaching intensifying in Hawaii and high ocean temperatures threatening Caribbean corals. It’s expected that these kinds of events are only going to get stronger and more frequent over the coming decades if the world's ocean temperatures continue to rise.

Not only is this a problem for the coral reefs, it also affects the multitude of marine life that lives among them.


Along with the Hawaiian reefs, US coral reefs in Guam, the Commonwealth of the Northern Mariana Islands, Florida Keys, US Virgin Islands, and Puerto Rico are also under threat by this wider theme of warming ocean temperatures. In April last year, it was reported that 93 percent of the Great Barrier Reef in Australia was bleached and 50 percent was dead or in the process of dying.

All in all, it’s not looking good for the world’s coral reefs, one of the most beautiful and unique ecosystems we have.


  • tag
  • climate change,

  • global warming,

  • coral bleaching,

  • Papahānaumokuākea,

  • hawaii coral reef