Corals worldwide hit by bleaching

The current coral bleaching event began last year in the Pacific Ocean. This reef in American Samoa was healthy in December 2014 (left) but had lost its characteristic colour in February 2015 (right). Image courtesy of XL Catlin Seaview Survey.

From Hawai‘i to Papua New Guinea to the Maldives, coral reefs are bleaching — in so many regions that the US National Oceanographic and Atmospheric Administration (NOAA) officially declared a global bleaching event on 08 October 2015. The event, the third in recorded history, is expected to grow worse in coming months.

Warm ocean temperatures, linked to climate change and a strengthening El Niño weather pattern, have triggered reefs to expel the algae that colour them. Reefs in parts of the Pacific, the Indian, and the Atlantic oceans have now turned white. By the end of the year, the bleaching could affect more than a third of the world’s coral reefs and kill more than 12,000 square kilometres of them, NOAA estimates.

“The temperatures we’re seeing are anomalies, and have the potential to dramatically impact the integrity of reefs around the world,” says Ruth Gates, director of the Hawaii Institute of Marine Biology (HIMB).

Read more about it at NOAA and in Nature News.