An alarming new study by the Australian Institute of Marine Science (AIMS) shows that the Great Barrier Reef has lost 50% of its coral cover over the past 27 years. The scientific group have attributed the loss to storm damage (48%), the growth of the Crown of Thorns starfish (42%) and bleaching (10%). In a study, which was published in the Proceedings of the National Academy of Sciences, the team noted that unless efforts are made to stop the coral loss, the reef will not be able to adapt to these challenges.
John Gunn, the CEO of AIMS said that one of the main problems is the Crown of Thorns starfish. “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.”
The marine creature has been cited as being responsible for more than two fifths of the overall coral loss. Capable of producing tens of millions of larvae, the starfish species can potentially strip entire reefs of coral.
“This finding is based on the most comprehensive reef monitoring program in the world. The program started broad scale surveillance of more than 100 reefs in 1985 and from 1993 it has incorporated more detailed annual surveys of 47 reefs,” added 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. ” Doherty stated.
As well as the starfish, intense tropical cyclones have also caused massive damage, primarily to reefs in the central and southern parts of the Reef. Two severe coral bleaching events have also had major detrimental impacts in northern and central parts of the reef.
“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,” said 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.”