SYDNEY, June 2 (Xinhua) -- The Great Barrier Reef has historically withstood rapid sea level rise, but only in the absence of additional environmental stressors, new research led by the University of Sydney revealed on Monday.
Drawing on fossil reef cores, a geological time capsule, drilled from the seabed beneath the current reef, the findings suggest that while sea level rise alone did not destroy the reef's ancient predecessor, a combination of factors such as warming temperatures and poor water quality ultimately led to its collapse around 10,000 years ago, according to a press release from the University of Sydney.
The research centers on the period about 11,450-11,100 years ago, a time of rapid polar ice melt and sea level rise. Analysis of 15- to 20-meter-long reef cores, taken from 40-50 meters below the seabed, reveals that sea levels likely rose 3-5 mm per year, comparable to today's rate, but less extreme than previously estimated.
The team's focus was Reef 4, a "proto-Great Barrier Reef" with similar coral and algae communities to the modern reef. Despite rising seas, it managed to survive until the compounding effects of climate-driven stress caused its demise.
Over the following 1,000-2,000 years, a new reef reestablished itself further inland, forming the present-day Great Barrier Reef, said the study published in Nature Communications.
"The modern reef faces rising sea levels, more heat waves and extensive bleaching, along with increasing sediment and nutrient input. This combination, on top of rising sea levels, is of deep concern," said the study's lead author Jody Webster from the University of Sydney.
If current conditions continue, the Great Barrier Reef may survive but is likely to undergo significant changes, becoming less diverse and structurally simpler over the next 50 to 100 years, Webster said.
"Understanding the environmental changes that influenced it, and led to its ultimate demise, therefore offers clues on what might happen to the modern reef," he said.
The study was conducted in collaboration with the Australian National University, University of Tokyo and Nagoya University in Japan, University of Granada in Spain, and Aix-Marseille University in France, under the International Ocean Discovery Program, a global marine research initiative. ■
