Bleaching hits world’s southernmost coral reef

Bleached coral reefs   | Photo Credit: AP

The world’s southernmost coral reef has been hit by bleaching this summer, Australian scientists said on Wednesday, as they warned rising sea temperatures from climate change were affecting even the most isolated ecosystems.

The corals off Lord Howe Island — some 600 km offshore from Sydney — were affected by elevated temperatures this summer, despite escaping severe bleaching that damaged the Great Barrier Reef in 2016 and 2017.

“It’s a canary in the coal mine that we are seeing bleaching at this very isolated southernmost reef,” said Bill Leggat of the University of Newcastle.

“It’s just another indicator that climate change is affecting everywhere around the world. Here is a reef that is 600 km from the mainland and we are seeing bleaching there in a lovely, beautiful ecosystem,” he said.

Shallow lagoons

Mr. Leggat and other scientists from several Australian universities and the U.S. National Oceanic and Atmospheric Administration found severe bleaching of up to 90% at Lord Howe’s inshore, shallow lagoon reefs. Deeper-water corals in the marine park, which contains species not found anywhere else and like the Barrier Reef is a World Heritage site, were still “looking quite healthy” having mostly escaped the bleaching, Mr. Leggat said.

Mr. Leggat said increasing baseline temperatures caused by climate change, and local factors such as elevated temperatures in the area this summer, caused the bleaching to occur. The scientists are set to return to Lord Howe in the next few months to find out if some corals have been so severely bleached they can’t recover.

Bleaching occurs when abnormal environmental conditions, such as warmer sea temperatures, cause corals to expel tiny photosynthetic algae, draining them of their colour.

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Printable version | May 14, 2021 6:50:19 PM |

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