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Half of Australia’s Great Barrier Reef, the largest coral reef in the world, has died in the last 25 years. Scientists warn that climate change is irreversibly affecting the underwater ecosystem.<!– –>
The Great Barrier Reef, the reserve northeast of the Australian mainland, has been a UNESCO World Heritage Site since 1981. But the study in the scientific journal Proceedings of the Royal Society is sounding the alarm about the extent to which all types of corals have declined since the mid-1990s.
Ecosystem changes
The largest types of coral, especially those in the shape of a round table and those with branches, have been hit the hardest. So much so that some species disappear in the most northern part of the reef. “Eighty to ninety percent of it has disappeared since 25 years ago,” said Terry Hughes, a professor at James Cook University, one of the study’s authors. “They provide nooks and crannies in which to hide many fish and other creatures, and the loss of those huge three-dimensional corals will alter the entire ecosystem.” The Great Barrier Reef is not only invaluable from a natural and scientific point of view. The coral reef, which stretches for 2,300 kilometers, also generates $ 4 billion in revenue for the Australian tourism industry.<!– –>
Verbleking
Much of the decline of the Great Barrier Reef is due to periods of coral bleaching as a result of climate change. The algae that live in symbiosis with the corals – and give them color – are repelled by the rise in ocean temperature. When the water cools down, the reefs can recover. But they can also die if the phenomenon persists. In addition, the Great Barrier Reef is threatened by pollution from agriculture and economic development. Another threat is the crown of thorns, a starfish with thorny spines that grazes the coral. In 2016 and 2017, there were already two unseen coral bleaching periods. Before that, in 1998 and 2002, there were also two such periods. One fifth was observed in 2020, but the total damage has not yet been measured.
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