A landmark worldwide study of the Great Barrier Reef has shown that in the past 30,000 years the world's largest reef system has suffered five death events, largely driven by changes in sea level and associated environmental change.
According to a previous study published in Nature, roughly 29% of the 3,863 individual reefs that make up Australia's Great Barrier Reef were affected by the abnormal warming. This combination promotes coral bleaching, which occurs when the ocean's waters become too warm, resulting in the expelling of photosynthetic algae called zooxanthellae that live in a symbiotic relationship with the coral.
An global study led by Australian researchers on Tuesday revealed that the country's iconic Great Barrier Reef has survived five "death events" linked with climate changes.
However, scientists have assured us that the reef receives significant damage from pollution of the seas, which at it have a negative impact sedimentary rocks, formed due to the deterioration of water quality in the oceans.
The study was conducted over 10 years by an worldwide team of scientists, who drilled fossil reef cores from 16 sites along the northeastern Australian coast, and analyzed the dating, geomorphic, sedimentological and biological data from them. Lowest recorded sea level was 118 metres below what it is now and that happened about 21,000 years ago, with most of the water all trapped in polar ice caps. It survived that event, but it took many thousands of years for it to grow back to normal again. Graphic by James Tuttle Keane and courtesy of Nature Geoscience. During this period, the reef moved seaward to try to keep pace with the falling sea levels. The reef responded by moving back toward the sea.
Analysis of the core samples and data on sediment flux show these reef-death events from sea-level rise were likely associated with high increases in sediment.
The fact that the reef persisted through these events showed the researchers that it's more resilient in the face of danger than was previously thought.
But it remains an open question as to whether its resilience will be enough for it to survive the current decline of coral reefs, said Jody Webster, the lead researcher and associate professor at the University of Sydney. However, current forecasts of sea surface temperature change are around 0.7 degrees in a century. Note: material may have been edited for length and content.
Although the study shows that the Great Barrier Reef can show great resilience, Webster says it would be very hard for the reef to survive its current stressors, especially since the rise in the sea's surface temperature is occurring much faster than ever.