Sat, Mar 11, 2017 - Page 6 News List

Great Barrier Reef experiences second year of bleaching


A handout photograph made available by WWF-Australia yesterday shows the Great Barrier Reef experiencing mass coral bleaching for the second year in a row near Cairns, Australia, on Monday.

Photo: EPA

Australia’s Great Barrier Reef is experiencing an unprecedented second straight year of mass coral bleaching, scientists said yesterday, warning many species would struggle to fully recover.

The 2,300km reef last year suffered its most severe bleaching on record due to warming sea temperatures in March and April.

Bleaching is once again occurring, the government’s Great Barrier Reef Marine Park Authority said after an aerial survey off Australia’s eastern coast on Thursday.

“Regrettably, the temperatures have been high on the Great Barrier Reef this summer as well, and unfortunately [we] are here to confirm ... a mass coral bleaching event for the second consecutive year,” agency reef recovery director David Wachenfeld said in a video on Facebook. “And importantly, this is the first time we’ve ever seen the Great Barrier Reef bleached two years in sequence. We’ve seen heat stress build since December.”

The agency said more bleaching was being observed in the central part of the reef, which last year escaped widespread severe bleaching.

Last year’s bleaching was more severe in the northern areas of the biodiverse site.

The back-to-back occurrence of widespread bleaching also meant there was insufficient time for corals to fully recover, the Australian Institute of Marine Science’s Neal Cantin said.

“We are seeing a decrease in the stress tolerance of these corals,” Cantin added in a statement. “This is the first time the Great Barrier Reef has not had a few years between bleaching events to recover.”

“Many coral species appear to be more susceptible to bleaching after more than 12 months of sustained above-average ocean temperatures,” he added.

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

Corals can recover if the water temperature drops and the algae are able to recolonize them.

However, researchers in January said coral reefs that survive rapid bleaching fueled by global warming would remain deeply damaged with little prospect of full recovery.

The Great Barrier Reef escaped with minor damage after two other bleaching events in 1998 and 2002.

Conservation group WWF-Australia yesterday said that the latest bleaching increased the urgency of tackling climate change in Australia, one of the world’s worst per capita greenhouse gas polluters.

“I did not anticipate back-to-back bleaching this decade,” WWF-Australia oceans division head Richard Leck said. “Scientists warned that without sufficient emissions reductions we could expect annual mass bleaching of the Great Barrier Reef by 2050. Consecutive bleaching events have arrived 30 years early.”

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