Leeds academics involved in coral reef bleaching study

Australia’s Great Barrier Reef may never recover from last year’s warming-driven coral bleaching, said a study Wednesday that called for urgent action in the face of ineffective conservation efforts.

All these unfortunate changes in the Great Barrier Reef are telling signs of the health of the seas caused by the global climate change. “This one won’t be as bad as 2016, but it could be more comparable to 1998 or 2002”, explained Hughes, director of the ARC Center of Excellence for Coral Reefs Studies at James Cook University in Townsville, Australia.

The Great Barrier Reef has experienced three major bleaching events in its history.

“It broke my heart to see so many corals dying on northern reefs on the Great Barrier Reef in 2016”, said Hughes. But rising global temperatures due to greenhouse gas emissions have damaged large parts of the reef.

“The loss of these colourful algae causes the corals to turn white”, he said. Corals generally require warm water to flourish.

The National Oceanic and Atmospheric Administration released a graphic this month showing all tropical oceans on the planet were “unusually hot” from January 2014 to December 2016, a period “tightly linked” with the Great Barrier’s mass bleaching. Huge swathes of reefs were devastated a year ago in the worst mass bleaching incident on record, with up to 83 percent of corals dying in certain areas, such as a long stretch north of Port Douglas. If the coral reefs die, we would lose some of the richest and most colorful life forms in the ocean. While the faster-growing coral can usually recover in between bleaching events, that’s not an option for others. However, the severity of the 2016 event saw multiple types of mortality occur.

This compares with 45 per cent in 1998 and 42 per cent in 2002 – making up the three major episodes over the past two decades.

Bleaching is caused by thermal stress – high water temperatures during marine heatwaves – which disrupts the relationship between corals and the algae living within them.

It doesn’t necessarily kill the coral, but it subjects them to extra stress, lowering the chance of survival.

Hughes believes that the world can still have coral reefs if the temperatures are maintained below 2 degrees, but not at 1 ½ degrees. Their preservation holds humanitarian interest, too, as hundreds of millions of people depend on reef fish for protein, The New York Times reports. Key ecological processes are under threat, such as providing habitat, calcification (the formation of corals’ reef-building stony skeletons) and predation (creatures eating and being eaten by corals). It is worth worrying about, though, because of the fact that coral bleaching has happened in that same area two years in a row. The ocean absorbs about 93 percent of the Earth’s increasing heat.

With even the most pristine areas affected by heat, the researchers warned tough action on global warming was needed to ensure the reef’s future.