Largest coral die-off recorded
Environmentalists call for Australian govt to abandon coal mining to help prevent further bleaching disasters
A mass bleaching event on the Great Barrier Reef this year killed more corals than ever before, scientists said on Tuesday, sounding the alarm over the delicate ecosystem.
The 2,300-kilometer 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.
Follow-up underwater surveys, backing earlier aerial studies, have revealed a 700km stretch of reefs in the lessaccessible north lost two-thirds of shallow-water corals in the past eight to nine months.
“Most of the losses in 2016 have occurred in the northern, most-pristine part of the Great Barrier Reef,” said Terry Hughes, head of the Center of Excellence for Coral Reef Studies at James Cook University.
“This region escaped with minor damage in two earlier bleaching events in 1998 and 2002, but this time around it has been badly affected.”
Further south over the vast central and southern regions, including major tourist areas around Cairns and the Whitsunday Islands, there was a much lower toll.
Fossil fuels
Bleaching occurs when abnormal environmental conditions, such as warmer sea temperatures, cause corals to expel tiny photosynthetic algae, draining them of their color.
Most of the losses in 2016 have occurred in the northern, most-pristine part of the Great Barrier Reef.” Terry Hughes, head of the Center of Excellence for Coral Reef Studies at James Cook University
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 recolonize them.
Environmentalists blame the burning of fossil fuels for global warming and repeated calls on Tuesday for Australia to abandon coal mining to help prevent further bleaching disasters.
Canberra insists it is doing more than ever to safeguard the reef, which is also under pressure from farming runoff, development and the coral-eating crown-of-thorns starfish, committing more than $1.50 billion over the next decade.
Tourism industry
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 center 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.
Given reefs need so long to recover from severe bleaching, it said “we are likely to lose large parts of the Great Barrier Reef in just a couple of decades”.
There have been fears that the bleaching would badly hurt the tourism industry. Tourism on the World Heritage-listed reef employs 70,000 people and generates $3.7 billion in income each year.
Australia last year narrowly avoided UNESCO putting the site on its endangered list and must report to the World Heritage committee by Dec 1 on the progress being made to rescue the reef.