The Great Barrier Reef Has Lost Half of its Coral in the Last 27 Years

A new study published in the journal Proceedings of the National Academy of Sciences has found that the Great Barrier Reef in Australia has lost half of its coral in the last 27 years thanks to storm damage, crown of thorns starfish and bleaching.

The study, conducted by researchers from the Australian Institute of Marine Science (AIMS) in Townsville and the University of Wollongong, clearly shows the overwhelming responsibility laid at the feet of the three factors:  storm damage (48%), crown of thorns starfish (42%), and bleaching (10%).

The Great Barrier Reef Has Lots Half of its Coral in the Last 27 Years
Healthy reef at Carter Reef (credit: AIMS Long-term Monitoring Team)

“This finding is based on the most comprehensive reef monitoring program in the world. The program started broadscale surveillance of more than 100 reefs in 1985 and from 1993 it has incorporated more detailed annual surveys of 47 reefs,” says one of the program’s original creators, Dr Peter Doherty, Research Fellow at AIMS.

“Our researchers have spent more than 2,700 days at sea and we’ve invested in the order of $50 million in this monitoring program.”

“The study shows the Reef has lost more than half its coral cover in 27 years. If the trend continued coral cover could halve again by 2022. Interestingly, the pattern of decline varies among regions. In the northern Great Barrier Reef coral cover has remained relatively stable, whereas in the southern regions we see the most dramatic loss of coral, particularly over the last decade when storms have devastated many reefs. ” says Doherty.

The Great Barrier Reef Has Lots Half of its Coral in the Last 27 Years
Health reef at Low Islands (credit: AIMS Long-term Monitoring Team)

“Our data show that the reefs can regain their coral cover after such disturbances, but recovery takes 10-20 years. At present, the intervals between the disturbances are generally too short for full recovery and that’s causing the long-term losses,” added Dr Hugh Sweatman, one of the study’s authors.

“We can’t stop the storms, and ocean warming (the primary cause of coral bleaching) is one of the critical impacts of the global climate change,” says AIMS CEO, John Gunn. ”However, we can act to reduce the impact of crown of thorns,” he says. “The study shows that in the absence of crown of thorns, coral cover would increase at 0.89% per year, so even with losses due to cyclones and bleaching there should be slow recovery.

“We at AIMS will be redoubling our efforts to understand the life cycle of crown of thorns so we can better predict and reduce the periodic population explosions of crown of thorns. It’s already clear that one important factor is water quality, and we plan to explore options for more direct intervention on this native pest.”

The Great Barrier Reef Has Lots Half of its Coral in the Last 27 Years
Bleaching at North Kepplel (credit: Ray Berkelmans, Australian Institute of Marine Science)

Interestingly, the Australian Government admitted Wednesday that they had not done enough to protect the Great Barrier Reef, saying the it had been neglected for decades.

Environment Minister Tony Burke said research released Tuesday by scientists from the Australian Institute of Marine Science and the University of Wollongong should be setting off alarm bells across the country.

“I reckon the report would have sent shockwaves through a whole lot of households,” he told ABC television late Tuesday. “We’ve all heard about damage to the reef over the years, but that 50 percent figure, I think, rang a warning bell loud and clear for many people.”

Source: Science in Public

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