Environmental News

Coral Bleaching Is Killing One-Third Of The Great Barrier Reef

Photo from Pixabay

Scientists who have completed months of aerial and underwater studies of Australia’s Great Barrier Reef have found that mass bleaching has killed more than a third of the corals in its northern and central parts, casting a shadow on its future.

The Great Barrier Reef, which spans 2,300 kilometers off Australia’s north-east coast is the world’s largest collection of coral reefs, home to a vast number of marine species and is a protected UNESCO World Heritage site.

However, recent surveys reported by the New York Times have shown that around 35% of these corals are either dead or dying, although corals in the south have little damage. Some parts of the reef have lost over half of their coral due to bleaching, Terry Hughes, director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Queensland said.

Hughes adds that the extent of this damage, which has occurred only in the past months, has serious implications. While bleached corals that are still alive may recover if the water temperature drops, older corals take longer to recover and are unlikely to survive before the next bleaching happens. Coral that has died is dead for good, which in turn severely impacts marine life that rely on it for food and shelter.

Mark Eakin, coral reef watch coordinator for the US National Oceanic and Atmospheric Administration, says, “Is it surprising? Not anymore. Is it significant? Absolutely.”

We’re talking about losing 35 percent of the population of coral in some of these reefs — that’s huge.

This damage comes from a huge bleaching event that has been having an effect on coral reefs all over the world for the past two years. Scientists say the bleaching happened due in part because of global warming and El Nino, which has warmed parts of the Pacific Ocean and changed weather conditions worldwide. Hot ocean waters puts a strain on corals, making them turn white and susceptible to disease. Other reefs have reported greater damage, like some Pacific islands with 80% coral death rates, Eakin mentioned.

Hughes said that this is the third and worst mass bleaching that has happened in 18 years in the Great Barrier Reef. In each case, the areas that suffered the most bleaching were the areas with the hottest water temperatures for the longest time.

The southern portion of the reefs were spared because of a tropical cyclone in the South Pacific that brought cloud cover and heavy rains, cooling the ocean enough to halt any bleaching that had begun. Around 95% of the coral in the south are intact.

Storms have been proven to be helpful for heat-stressed reefs, Eakin said. In 2005, the successive Hurricane Katrina and Hurricane Rita cooled the oceans as they passed Florida, saving the Florida Keys from an extreme coral bleaching event that extended to the Caribbean.

There have been experiments conducted to lower water temperature, including using shade to cover the corals, Eakin said. However, these efforts require plenty of preparation and can only be accomplished in small areas. Other possible solutions may be to find ways to limit stress-inducing factors to the vulnerable reefs.

Anything you can do to reduce the level of injury and stress coming from other sources, the better the chance that the corals are going to survive,

Eakin said. “Those reefs that have recovered after events like this are the ones that are the most protected, least visited and least disturbed.”

Just last year, the United Nations expressed its concern over the state of the Great Barrier Reef and pushed for Australia to do more in its conservation.

Australian politicians, who are in the midst of election campaigns, have jumped on the issue, with the Labor Party pledging a $500 million fund for the management of and further research on the reef. Environment Minister Greg Hunt announced that if re-elected, the government would put $6 million towards managing crown-of-thorns starfish, which feast on coral.


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