The reefs of the Great Barrier Reef in Australia have experienced an unprecedented coral bleaching for the second consecutive year, scientists said Friday.
The 2300 km ecosystem – the largest in the world – last year suffered the most severe bleaching episode on record, due to warming ocean temperatures in March and April.
Bleaching continues once again, observed the Great Barrier Reef Marine Park, following aerial surveys over the northeast coast of Australia.
“Unfortunately, temperatures have been high this summer at the Great Barrier Reef, and we are here to confirm a massive bleaching episode for the second consecutive year,” park manager David Wachenfeld said in a video on Facebook.
“But most importantly, this is the first time we have seen a whitening of the Great Barrier Reef over two years. We have seen an increase in heat since December, “he said.
Two years in a row is too much for ecosystem
This phenomenon two years in a row means that corals do not have enough time to recover fully, observes Neal Cantin of the Australian Institute of Marine Sciences.
“We see a reduction in the stress resistance of these corals. This is the first time that the Great Barrier has not had a few years to recover from bleaching episodes, “he said.
“Many coral species appear to be more vulnerable to bleaching after more than 12 months of exposure to ocean temperatures that are permanently above average,” the scientist added.
Coral bleaching is a phenomenon of dieback which results in discoloration. It is caused by the rise in temperature of the water, which causes the expulsion of symbiotic algae which give the coral its color and nutrients.
The reefs can recover if the water cools, but they can also die if the phenomenon persists.
The Great Barrier, registered as a World Heritage site since 1981, is threatened by global warming, agricultural runoff, economic development and the proliferation of acanthuses, starfish that destroy corals.