April Flowers for redOrbit.com – Your Universe Online
The Great Barrier Reef in Australia is the world’s largest coral reef, and the only living thing on Earth that is visible from space. The Great Barrier Reef is approximately 3000 kilometers long and up to 65 kilometers wide in some places.
According to new research from the Australian Institute of Marine Science (AIMS ), the Great Barrier Reef has lost half of its coral cover in the last 27 years. The research team attributes this loss to storm damage (48%), crown of thorns starfish (42%), and bleaching (10%).
“We can’t stop the storms but, perhaps we can stop the starfish. If we can, then the Reef will have more opportunity to adapt to the challenges of rising sea temperatures and ocean acidification,” said John Gunn, CEO of Aims.
According to Dr. Peter Doherty, one of the program’s creators, this is the most comprehensive reef-monitoring program in the world. AIMS started broad scale surveillance of more than 100 reefs in 1985. By 1993, the program was incorporating more detailed annual surveys of 47 reefs.
“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,” he says.
“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.
Three factors have shown themselves to be overwhelmingly responsible for this nearly catastrophic loss. Tropical cyclones have caused massive damage to the Reef, especially in the central and southern areas. There has also been a population explosion of the coral-consuming Crown-of-thorns starfish, which has had a detrimental effect on the coral populations. Finally, there have been two severe coral bleaching events in the northern and central parts of the GBR.
The team asserts that the reefs can regain its coral cover after such events, but it generally takes 10—20 years. The time interval between disturbances is too short for full recovery, which is leading to long-term losses, according to Dr. Hugh Sweatman.
“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 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 results of their study have been published in the journal, Proceedings of the National Academy of Sciences.