In the Great Barrier Reef In the marine park, 73 percent of surveyed reefs show widespread bleaching, meaning more than 10 percent of coral cover is bleached, the Great Barrier Reef Marine Park Authority, which manages The area. Very significant and extreme bleaching was observed over almost 40 percent of the reef system.
“Climate change poses the greatest threat to the Great Barrier Reef and coral reefs around the world,” said Roger Beeden, the authority’s chief scientist. “The Great Barrier Reef is an incredible ecosystem and while it has demonstrated its resilience time and time again, this summer has been particularly challenging. »
This dire update on Earth’s largest reef system comes just days after scientists from the U.S.-based National Oceanic and Atmospheric Administration and the International Coral Reef Initiative said abnormal ocean temperatures were plaguing reefs around the world.
According to NOAA scientists, the world is experiencing its fourth global bleaching event, and the second in the last decade. At least 53 countries and local regions have experienced mass bleaching in the Atlantic, Pacific and Indian Oceans, they said.
Ocean temperatures began to rise in the Great Barrier Reef region in late December and continued to rise throughout the southern hemisphere summer, causing “the highest levels of heat stress on record”, the marine park authority said.
The most intense and prolonged heat stress occurred on coastal reefs in the southern part of the marine park, with sea surface temperatures peaking at 2.5 degrees Celsius (4.5 degrees Fahrenheit) at -above average.
This is the fifth major bleaching event on the Great Barrier Reef in nine years. Scientists say it could be the biggest test ever of the 2,400-mile-long world wonder’s recovery capability. For the first time, extreme bleaching – where more than 90 percent of a reef’s coral cover is bleached – has been observed in all three regions of the marine park.
“The southernmost parts of the reef, which had been largely spared previously, were particularly hard hit this time around, with bleaching affecting many more species, extending to greater depths and affecting some of the most oldest and most resilient,” said Simon Bradshaw. research director at the Climate Council, a non-profit organization. “It’s a disaster upon us.”
The giant reef system – so vast it can be easily spotted from space – has recovered from past disruptions, including underwater heatwaves in 2016 and 2017 that triggered coral bleaching events so severe that scientists feared the reef would never look like this one. yet the same.
Scientists say the recovery after these events was driven by rapid growth Acropora corals, more vulnerable to thermal stress and coral bleaching.
“The Great Barrier Reef has seen its coral cover increase to high levels in recent years, indicating that it remains a resilient system. But this resilience has its limits,” said David Wachenfeld, research program director at the Australian Institute of Marine Science, a government agency.
Wachenfeld said the level of heat stress and aerial survey results indicate the latest bleaching event is “one of the most extensive” the reef has seen since the agency began monitoring the reef ages ago. almost 40 years.
Research divers observed coral deaths in every region of the reef, he said.
washingtonpost
