Bleach­ing kills third of coral in Great Bar­rier Reef’s north

Business Mirror - - THE WORLD -

SYDNEY—Mass bleach­ing has killed more than a third of the coral in the north­ern and cen­tral parts of Aus­tralia’s Great Bar­rier Reef, though corals to the south have es­caped with lit­tle da­m­age, sci­en­tists said on Mon­day.

Re­searchers who con­ducted months of aerial and un­der­wa­ter sur­veys of the 2,300-kilo­me­ter reef off Aus­tralia’s east coast found that around 35 per­cent of the coral in the north­ern and cen­tral sec­tions of the reef are dead or dy­ing, said Terry Hughes, di­rec­tor of the ARC Cen­tre of Ex­cel­lence for Coral Reef Stud­ies at James Cook Univer­sity in Queens­land state. And some parts of the reef had lost more than half of the coral to bleach­ing.

The ex­tent of the da­m­age, which has oc­curred in just the past cou­ple of months, has se­ri­ous im­pli­ca­tions, Hughes said. Though bleached corals that haven’t died can re­cover if the wa­ter tem­per­a­ture drops, older corals take longer to bounce back and likely won’t have a chance to re­cover be­fore the next bleach­ing event oc­curs, he said.

Coral that has died is gone for good, which af­fects other crea­tures that rely on it for food and shel­ter.

“Is it sur­pris­ing? Not any­more. Is it sig­nif­i­cant? Ab­so­lutely,” said Mark Eakin, the coral- reef watch co­or­di­na­tor for the US Na­tional Oceanic and At­mo­spheric Ad­min­is­tra­tion. “We’re talk­ing about los­ing 35 per­cent of the pop­u­la­tion of coral in some of these reefs— that’s huge.” The da­m­age is part of a mas­sive bleach­ing event that has been im­pact­ing reefs around the world for the past two years. Ex­perts say the bleach­ing has been trig­gered by global warm­ing and El Niño, a warm­ing of parts of the Pa­cific Ocean that changes weather world­wide.

Hot wa­ter puts stress on coral, caus­ing it to turn white and be­come vul­ner­a­ble to dis­ease. Other reefs have suf­fered even more se­verely from the re­cent bleach­ing. Some Pa­cific is­lands, for ex­am­ple, have re­ported over 80- per­cent coraldeath rates, Eakin said.

This is the third and most ex­treme mass-bleach­ing event in 18 years to strike the Great Bar­rier Reef, and in each case, the ar­eas that suf­fered the worst bleach­ing were the ar­eas where the wa­ter was hottest for the long­est pe­riod of time, Hughes said.

This time the south­ern half of the reef was spared largely due to a lucky break that ar­rived in the form of a trop­i­cal cy­clone.

The rem­nants of the storm, which had lashed the South Pa­cific brought cloud cover and heavy rains to the re­gion, cool­ing the ocean enough to stop bleach­ing that had just be­gun in the south. About 95 per­cent of the coral in the south­ern por­tion of the reef has sur­vived.

Storms have pre­vi­ously proven very help­ful for heat- stressed reefs, Eakin said. In 2005, for in­stance, the quick suc­ces­sion of Hur­ri­cane Ka­t­rina and Hur­ri­cane Rita cooled the wa­ters be­low as they passed over Florida, spar­ing the Florida Keys from a se­ri­ous coral-bleach­ing event af­fect­ing the Caribbean.

Ex­per­i­men­tal ap­proaches to the bleach­ing dilemma have in­cluded at­tempts to lower wa­ter tem­per­a­tures by us­ing shades to cover corals, Eakin said. But such ef­forts re­quire mas­sive amounts of prepa­ra­tion and can only be done in small ar­eas, Eakin added. Other so­lu­tions may lie in find­ing ways to min­i­mize ad­di­tional stres­sors to the al­ready frag­ile reef.

“Any­thing you can do to re­duce the level of in­jury and stress com­ing from other sources, the bet­ter the chance that the corals are go­ing to sur­vive,” Eakin said. “Those reefs that have re­cov­ered after events like this are the ones that are the most pro­tected, least vis­ited and least dis­turbed.”

Last year the United Na­tions’s her­itage body ex­pressed con­cern about the state of the Great Bar­rier Reef and urged Aus­tralia to boost its con­ser­va­tion ef­forts.

Fol­low­ing the re­lease of the bleach­ing re­port on Mon­day, Aus­tralian politi­cians— who are in the midst of an elec­tion cam­paign— jumped on the is­sue, with the op­po­si­tion La­bor Party pledg­ing to cre­ate a $ 500- mil­lion fund for bet­ter man­age­ment and re­search of the reef. En­vi­ron­ment Min­is­ter Greg Hunt, mean­while, an­nounced that if his party is re­elected, the gov­ern­ment would in­vest $ 6 mil­lion to help­ing com­bat the crown- of- thorns starfish, which feast on coral.

DAVID BELLWOOD/ARC CEN­TRE OF EX­CEL­LENCE FOR CORAL REEF STUD­IES VIA AP

THIS April 2016 photo re­leased on Mon­day by ARC Cen­tre of Ex­cel­lence for Coral Reef Stud­ies shows ma­ture stag-horn coral dead and over­grown by al­gae at Lizard Is­land, Great Bar­rier Reef off the eastern coast of north­ern Aus­tralia. The reef stud­ies cen­ter re­leased the re­sults of its sur­vey of the 2,300-kilo­me­ter reef off Aus­tralia’s east coast.

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