Mass Coral Bleaching at Great Barrier Reef

IAS Prelims 2023

According to latest reports, mass bleaching event on the Great Barrier Reef this year killed more corals than ever before.

The 2,300-kilometre long reef — the world’s biggest — suffered its most severe bleaching in recorded history, due to warming sea temperatures during March and April, with the northern third bearing the brunt.

Most of the losses in 2016 have occurred in the northern, most-pristine part of the Great Barrier Reef.

This region escaped with minor damage in two earlier bleaching events in 1998 and 2002, but this time around it has been badly affected.

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

Algae are vital to the coral, which uses the organic products of photosynthesis to help it grow.

The loss of algae makes the host vulnerable to disease and means it will eventually die.

However, coral can recover if the water temperature drops and the algae are able to recolonise them.

Environmentalists blame the burning of fossil fuels for global warming and repeated calls for Australia to abandon coal mining to help prevent further bleaching disasters.

On average, six percent of bleached corals died in the central region in 2016, and only one percent in the south. The corals have now regained their vibrant colour, and these reefs are in good condition.

Scientists estimate the northern region, which teems with marine life, will take at least 10-15 years to regain lost corals, but are concerned that a fourth major bleaching event may occur before that, hampering the recovery.

The reef studies centre warned earlier this year that if greenhouse gas levels keep rising, similar events would be the new normal, occurring every two years by the mid-2030s.