NOAA says coral reefs worldwide hit by bleaching

Extensive stand of severely bleached coral at Lisianski Island in the Papahanaumokuakea Marine National Monument in Hawaii, documented during an August 2014 NOAA research mission. (Credit: NOAA).
Extensive stand of severely bleached coral at Lisianski Island in the Papahanaumokuakea Marine National Monument in Hawaii, documented during an August 2014 NOAA research mission. (Credit: NOAA).

Up to 95 percent of U.S. coral reefs may be affected

Staff Report

Global warming is causing global coral bleaching, ocean scientists said today, confirming that rising ocean temperatures are resulting in massive and widespread impacts to reefs around the world.

“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,” NOAA’s Coral Reef Watch coordinator, Mark Eakin, said in a statement.“As a result, 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,” Eakin added.

The researchers have already documented reef degradation around Hawaii, and now they’re confirming that the same stressful conditions are expanding to the Caribbean and may last into the new year, prompting the declaration of the third-ever global coral bleaching event.

Waters are warming in the Caribbean, threatening coral in Puerto Rico and the U.S. Virgin Islands, NOAA scientists said. Coral bleaching began in the Florida Keys and South Florida in August, but now scientists expect bleaching conditions there to diminish.

Corals can recover from mild bleaching, but an extended event like the current warm spell is likely to kill extensive areas of reef. Degraded reefs leave shorelines vulnerable to erosion and less habitat for fish.

The NOAA scientists said the current bleaching episode is heating U.S. coral reefs especially hard. 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.

The biggest risk right now is to the Hawaiian Islands, where bleaching is intensifying and is expected to continue for at least another month. Areas at risk in the Caribbean in coming weeks include Haiti, the Dominican Republic and Puerto Rico, and from the U.S. Virgin Islands south into the Leeward and Windward islands.

The still-strengthening El Niño could make things even worse, with yet more bleaching in the Indian and southeastern Pacific Oceans after the new year. This may cause bleaching to spread globally again in 2016.

“We need to act locally and think globally to address these bleaching events,” said said Jennifer Koss, NOAA Coral Reef Conservation Program acting program manager. “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,” Koss said.

“To solve the long-term, global problem, however, we need to better understand how to reduce the unnatural carbon dioxide levels that are the major driver of the warming,” she added.

NOAA made the announcement based on satellite readings that were confirmed by reef visits by divers. The agency predicted the bleaching event in July.

The current high ocean temperatures around Hawaii come on the heels of bleaching in the Main Hawaiian Islands in 2014―only the second bleaching occurrence in the region’s history, as well as 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.”

Coral bleaching occurs when corals are exposed to stressful environmental conditions such as high temperature. Corals expel the symbiotic algae living in their tissues, causing corals to turn white or pale. Without the algae, the coral loses its major source of food and is more susceptible to disease.

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.

For more information on coral bleaching and these products, visit: http://www.coralreefwatch.noaa.gov/satellite/index.php.

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