Half the coral has disappeared from Australia’s Great Barrier Reef over the past 27 years, much of it due to factors influenced by human activity, according to scientists at the Australian Institute of Marine Science (AIMS) and the University of Wollongong.
Storm damage accounted for 48 percent of the loss, an invasion of crown of thorns starfish for 42 percent and bleaching took the other 10 percent, the researchers reported in the journal Proceedings of the National Academy of Sciences.
“If the trend continued, coral cover could halve again by 2022,” said Peter Doherty, an AIMS research fellow at AIMS, in a statement from the institute.
“Interestingly, the pattern of decline varies among regions,” Doherty said. “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.”
The stability in the northern part of the reef augured well for coral’s recuperative powers, if given the right circumstances, he and others said.
“Our data show that the reefs can regain their coral cover after such disturbances, but recovery takes 10 to 20 years,” said study co-author Hugh Sweatman. “At present, the intervals between the disturbances are generally too short for full recovery and that’s causing the long-term losses.”
Bleaching due to ocean warming, which stems from climate change, is one of the main human causes of the coral’s decline, the researchers said. But controlling the crown of thorns starfish could be key.
“We can’t stop the storms, and ocean warming is one of the critical impacts of the global climate change,” said John Gunn, the CEO of AIMS. “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.”
The Australian government has been working to preserve the reef with the help of aboriginals whose clans and bands are stewards of the reef. Several aboriginal groups are co-stewards of the Great Barrier Reef, including Torres Strait Islanders, according to the government’s Reef Rescue Land and Sea Country Indigenous Partnerships Program. In 2008 this program was given $10 million over five years under the auspices of the Great Barrier Reef Marine Park Authority (GBRMPA), which is part of Australia’s Caring for our Country program. In August 2012 the partnership held a workshop, the Saltwater Women’s Gathering, on Yunbenun (Magnetic Island) to get indigenous women more involved in stewardship, the Australian site PS News reported.
The scientists’ announcement comes right on the heels of Google Street View’s much-heralded unveiling of the undersea world of the Great Barrier Reef as well as two others. Besides Heron Island off Australia, the “street view” offers views of Lady Elliott Island on the Great Barrier Reef, the Molokini Crater off Maui, Hawaii, and Hanauma Bay in Oahu, Hawaii, and Philippines’ Apo Islands, the Los Angeles Times reported on September 27.
BBC News reported on today’s revelations, below.