Global coral bleaching event declared

A global coral bleaching event declared last week by the NOAA could have devastating effects on marine ecosystems and the economies of their neighboring regions. Photo: Jorge Láscar / Flickr

The National Oceanic and Atmospheric Administration (NOAA) last week declared the third global coral bleaching event ever on record following a year of widespread coral damage starting in the north Pacific and expanding to the south pacific and Indian oceans before reaching Hawaii and the Caribbean.

"The coral bleaching and disease, brought on by climate change and coupled with events like the current El Niño, are the largest and most pervasive threats to coral reefs around the world," said Mark Eakin, NOAA's Coral Reef Watch coordinator. "We are losing huge areas of coral across the U.S., as well as internationally. What really has us concerned is this event has been going on for more than a year and our preliminary model projections indicate it's likely to last well into 2016."

NOAA estimates that by the end of 2015, almost 95 percent of U.S. coral reefs will have been exposed to ocean conditions that can cause corals to bleach, and in the Pacific Ocean coral reefs are declining at a rate of about two percent a year. Scientists warn it may be only 40 to 50 years before they're completely gone.

Coral bleaching is caused by warming waters-as little as one degree- which cause corals to expel the symbiotic algae in their tissues turning them white or pale. Without the algae the coral loses its main source of food and is increasingly susceptible to disease. Coral can recover from mild bleaching, but the severe and long-term bleaching that is occurring across the oceans is often lethal. When corals die, reefs degrade and structures built by corals erode leaving less shoreline protection from storms and diminished habitats for marine life.

Much of the fish and marine animals that are harmed by diminishing reefs are vital to biodiversity and the health of local and global economies. Reefs are also a vital source of food and tourism for the regions near these reefs like Hawaii and Australia.

Scientists are also concerned about the impact of the strong El Niño, which climate models indicate will cause bleaching in the Indian and southeast Pacific Oceans in 2016. This may cause bleaching to spread globally again in the new year.

"We need to act locally and think globally to address these bleaching events. Locally produced threats to coral, such as pollution from the land and unsustainable fishing practices, stress the health of corals and decrease the likelihood that corals can either resist bleaching, or recover from it," said Jennifer Koss, NOAA Coral Reef Conservation
Program acting program manager. "However, to solve the long-term, global problem, we need to better understand how to reduce the unnatural carbon dioxide levels that are the major driver of the warming."

This most recent event follows the second bleaching in the history of the main Hawaiian Islands in 2014 and devastating bleaching and coral death in parts of the remote and well-protected Papahānaumokuākea Marine National Monument in the Northwestern Hawaiian Islands.

"Last year's bleaching at Lisianski Atoll was the worst our scientists have seen," said Randy Kosaki, NOAA's deputy superintendent for the monument. "Almost one and a half square miles of reef bleached last year and are now completely dead."

Though New Zealand does not have coral reefs, it has coral communities in the Kermadec Islands and the Bay of Islands which may also be affected by climate change.

In June the American Samoa Department of Marine and Wildlife Resources asked the community to report signs of bleaching after reports of white in nearby reefs caused by high sea temperatures in 2015.

The first global bleaching event was in 1998, during a strong El Niño that was followed by an equally very strong La Niña. A second one occurred in 2010.

Satellite data from NOAA's Coral Reef Watch program provides current reef environmental conditions to quickly identify areas at risk for coral bleaching and climate model-based outlooks provide information on potential bleaching months in advance.

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