Global warm­ing threat­ens our reefs. Some ma­rine sci­en­tists have a con­tro­ver­sial plan to save them. EL­IZ­A­BETH FINKEL ex­plains.

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THE AUS­TRALIAN IN­STI­TUTE of Ma­rine Science is a glo­ri­ous place. From sul­try Townsville in far north Queens­land, it’s a lush 50 km drive east through sugar cane and mango plan­ta­tions, across an es­tu­ary and through scrub till fi­nally you crest a hill and are hit by the blue ex­panse of the Pa­cific Ocean.

A PRIMEVAL AT­MOS­PHERE reigns at Cape Fer­gu­son. Signs on the dock warn of crocodiles, sharks and snakes. Every­thing is pro­tected and thrillingly feral.

Some­thing quite wild is hap­pen­ing in­side the build­ings too. Here, ma­rine bi­ol­o­gist Madeleine van Op­pen and col­leagues are pur­su­ing a bold, and con­tro­ver­sial, goal – to speed up the evo­lu­tion of corals to en­sure the sur­vival of the world’s reefs, par­tic­u­larly the one on the in­sti­tute’s doorstep, the 2,300 km-long Great Bar­rier Reef.

Their re­search, once con­sid­ered fringe, has gone main­stream. In Jan­uary the Aus­tralian gov­ern­ment com­mit­ted $6 mil­lion to a study on the fea­si­bil­ity of help­ing the reef adapt to cli­mate change. AIMS and CSIRO, the na­tional science agency, are lead­ing this study, which brings to­gether lead­ing reef con­ser­va­tion and re­search bodies: the Great Bar­rier Reef Ma­rine Park Au­thor­ity (GBRMPA), which man­ages the reef; the Great Bar­rier Reef Foun­da­tion, which raises funds for sci­en­tific re­search; the Univer­sity of Queens­land; the Queens­land Univer­sity of Tech­nol­ogy; and James Cook Univer­sity.

As­sist­ing the evo­lu­tion of co­ral is a rad­i­cal de­par­ture from the his­tor­i­cally con­ser­va­tive agenda of the reef’s cus­to­di­ans. Mostly the ef­forts have been to com­bat lo­cal threats, like agri­cul­tural runoff and preda­tory starfish. But the back-to-back bleach­ing events of 2016 and 2017 rammed home the greater ex­is­ten­tial threat from global warm­ing. “The nar­ra­tive that it will be our kids who have to deal with cli­mate change is ob­so­lete,” says Paul Hardisty, the head of AIMS. “We’re out of time; ac­tion has to hap­pen now.”

The fund­ing is just one-tenth of a $60 mil­lion reef pro­tec­tion pack­age an­nounced by the fed­eral gov­ern­ment, with the bulk ded­i­cated to re­duc­ing in­dus­try im­pacts on wa­ter qual­ity and man­ag­ing starfish. But the re­sults of the fea­si­bil­ity study may open the fund­ing flood gates.

How much is it worth spend­ing to save the reef? Its eco­log­i­cal value is im­mea­sur­able, but its eco­nomic value can be cal­cu­lated. Ac­cord­ing to an anal­y­sis by Deloitte Ac­cess Eco­nomics, reef tourism con­trib­utes more than $6 bil­lion a year to the Aus­tralian econ­omy. Add in the ser­vices to fish­eries and coastal pro­tec­tion, and it is an as­set val­ued at $56 bil­lion. Surely, worth a size­able chunk of re­search dol­lars to save it.

Ma­rine sci­en­tists, how­ever, are hardly com­rades in arms on the mer­its of ac­cel­er­ated evo­lu­tion.

While some feel com­pelled to try and pre­serve a ‘func­tional’ reef, oth­ers think the am­bi­tion is flawed and fu­tile. They say the scale of the reef is too vast for science to slow its de­cline, and any suc­cess may well de­feat the pur­pose. Rather than pre­serv­ing the di­ver­sity of its 400-plus hard co­ral species, it might pro­duce a reef dom­i­nated by a few co­ral ‘su­per­weeds’.

“One of my main ob­jec­tions is it’s more likely to do more harm than good,” says An­drew Baird, an ecol­o­gist at James Cook Univer­sity.

Yet oth­ers point to the daz­zling march of tech­nol­ogy and say we must at least ex­plore out­landish pos­si­bil­i­ties. The ad­vent of CRISPR gene edit­ing is an oft-cited ex­am­ple. Six years ago no one would have pre­dicted there would be a cheap, pre­cise, uni­ver­sally de­ploy­able tool for rewrit­ing the code of genes, or that ‘gene drives’ would be ca­pa­ble of rapidly al­ter­ing the ge­netic makeup of en­tire pop­u­la­tions.

Maybe within the next few decades, the ar­gu­ment goes, science will de­liver the tools to drive evo­lu­tion just where we want it to go.

Of course noth­ing will save co­ral if green­house gas emis­sions don’t cease. Co­ral is the ca­nary in the coalmine. It is exquisitely sen­si­tive to in­creases in wa­ter tem­per­a­ture – just a de­gree above the nor­mal max­i­mum for sev­eral weeks is enough to cause bleach­ing and death.

If the Paris cli­mate ac­cord holds and emis­sions cease by 2050, the hope is as­sisted evo­lu­tion will buy time for corals to adapt to 1-2 de­grees of warm­ing.

The sci­en­tists con­tem­plat­ing such pos­si­bil­i­ties say it is not just up to them to de­cide; they are look­ing to the public for per­mis­sion. “We try to en­gage the public at fo­rums and talk openly to the me­dia. It’s about be­ing trans­par­ent,” says van Op­pen.

So sooner or later, we’re all go­ing to have to ask this ques­tion: How far should we go to try to save our reefs?

AS­SIST THE EVO­LU­TION OF CO­RAL? It’s a sim­ple enough propo­si­tion. We know the Great Bar­rier Reef is a re­silient ecosys­tem. Around 100,000 years ago, there was no Great Bar­rier Reef. Vast ice sheets had locked up the planet’s wa­ter and left an an­cient ear­lier reef high and dry. As the ice sheets thawed and sea lev­els

rose, the reef slowly re­turned over the last 8,000 to 9,000 years with species adapted to the new con­di­tions. No doubt the reef will ul­ti­mately evolve new species and re­cover this time too, but we don’t want to wait 9,000 years.

We have been as­sist­ing the evo­lu­tion of species ever since we be­gan do­mes­ti­cat­ing crops and an­i­mals some 10,000 years ago. To­day’s wheat va­ri­eties, for ex­am­ple, bear lit­tle re­sem­blance to their weedy an­ces­tors. Co­ral, how­ever, is not wheat. It is the key­stone species of a wild ecosys­tem, and the ethos for con­serv­ing wilder­ness – forests, sa­van­nahs, sea­grass mead­ows or reefs – has al­ways been to pre­serve, not change.

His­tor­i­cally the cus­to­di­ans of the Great Bar­rier Reef have ad­hered to this ethos. They cor­doned off ar­eas, stopped over­fish­ing, reg­u­lated tourism, tried to keep wa­ters clean and bat­tled out­breaks of the Crown of Thorns starfish. The strat­egy seemed to be work­ing.

In 2010, for ex­am­ple, global bleach­ing events trig­gered by warm oceans ham­mered reefs across the Pa­cific, the In­dian Ocean, the Caribbean and the Arabian Gulf. But the Great Bar­rier Reef was largely spared. Some thought the reef was too big to fail.

Not so. The back-to-back bleach­ing events of 2016 and 2017 de­liv­ered the global co­ral apoc­a­lypse to Aus­tralian shores. The 2016 event, like pre­vi­ous mass bleach­ings, was linked to the warm­ing of Pa­cific wa­ters pro­duced by an El Nino weather pat­tern. The sec­ond was not. It took ev­ery­one by sur­prise.

Adding up the dam­age from the on­slaught, GBRMPA es­ti­mates about half the reef has died.

“The scale at which these im­pacts are op­er­at­ing is like noth­ing we’ve ever seen be­fore,” says David Wachen­feld, GBRMPA’S di­rec­tor of reef re­cov­ery. For Wachen­feld, busi­ness as usual is no longer an op­tion. “It’s a mo­ment in his­tory where [when it comes] to the pro­tec­tion of reef sys­tems, even one as big and ro­bust as the Great Bar­rier Reef, we have to re­think how we’re do­ing this.”

When it comes to as­sist­ing the evo­lu­tion of co­ral, van Op­pen, an ath­letic and af­fa­ble woman in her early 50s, has been ahead of the curve. “I felt it was just a mat­ter of time,” she says.

Orig­i­nally from the Nether­lands, one of her first projects led her to East Africa’s Lake Malawi to plumb the mys­tery of how its 700 species of ci­ch­lid fish had evolved so rapidly. She never dreamed that 20 years on, she would use her knowl­edge to speed up the evo­lu­tion of the corals of Aus­tralia’s Great Bar­rier Reef.

In 2008, based at AIMS, she be­gan try­ing to in­ter­breed the more heat-re­sis­tant Acro­p­ora mille­pora corals of Or­pheus Is­land with their southerly rel­a­tives in the Kep­pel is­lands. With the first at­tempt, flood­wa­ters washed away the ex­per­i­men­tal hy­brids, and yet again the fol­low­ing year. It was hard to find the fund­ing to re­peat the ex­per­i­ment – the key fo­cus at the time was man­ag­ing the clear and present dangers of the Crown of Thorns in­va­sion and the run-off from rivers that clouded and con­tam­i­nated the wa­ters of the in-shore reefs. Corals, es­pe­cially ju­ve­niles, need clear, clean wa­ter to thrive and re­pair the in­ces­sant dam­age wrought by starfish and cy­clones.

Van Op­pen found a like mind in co­ral re­searcher Ruth Gates at the Univer­sity of Hawaii. Hawai­ian reefs, though never as bio­di­verse as the Great Bar­rier Reef, had been dec­i­mated by bleach­ing events and sewage run-off.

In 2013 the col­lab­o­ra­tors at­tracted the at­ten­tion of Mi­crosoft co-founder Paul Allen’s phil­an­thropic foun­da­tion, win­ning a small $10,000 ex­ploratory grant. Two years later in 2015, af­ter a 2014 bleach­ing event had ham­mered corals in Kane’ohe Bay, the foun­da­tion kicked the re­search into high gear with a $4 mil­lion, five-year grant to “de­velop a bi­o­log­i­cal tool­box for cre­at­ing a stock­pile of corals with im­proved en­vi­ron­men­tal stress re­silience, which can then be used to sta­bilise and re­store reefs”.

When the first bleach­ing event hit Aus­tralia in 2016, van Op­pen found her­self in the right place at the right time. As the global me­dia re­ported apoc­a­lyp­tic scenes of mass bleach­ing, tepid wa­ters thick with the ooze of dy­ing corals, weep­ing sci­en­tists and wide­spread reef grief, van Op­pen’s once ob­scure re­search was

show­cased by the BBC’S David At­ten­bor­ough and the Aus­tralian ABC’S Cat­a­lyst pro­gram.

But it wasn’t just the me­dia that be­gan tak­ing se­ri­ous in­ter­est in her work. As the reef’s cus­to­dian, GBRMPA wres­tled with how to man­age the na­tional trea­sure in the face of a co­ral apoc­a­lypse and be­gan to take note of van Op­pen’s work, help­ing to re­cast it from fringe to trail­blaz­ing.

The cur­rent 18-month fea­si­bil­ity study is a hard­headed as­sess­ment of the tools avail­able to help the reef­s­cape adapt, how it could be done at scale, and at what cost. Be­sides lar­val seed­ing, un­der­wa­ter fans and shade cloth, these tools also in­clude the bi­o­log­i­cal tool­box de­vel­oped by van Op­pen.

So what ex­actly does the co­ral bi­o­log­i­cal tool­box con­tain? Lots. It in­volves tweak­ing the genes of co­ral, as well as the com­mu­nity of or­gan­isms that re­sides within it. The prob­lem is that no one has ever tried to tweak these genes be­fore. “We have to be care­ful not to over­promise,” says van Op­pen.

LET’S BE CLEAR. Co­ral is not a wheat plant. We’ve had thou­sands of years’ ex­pe­ri­ence tweak­ing the genes of wheat. We can make cross-breeds at will, map out de­sired traits in the DNA and usher them into new va­ri­eties. Breed­ing has pro­duced fan­tas­tic suc­cesses. Mod­ern wheats have more than dou­bled their yield since the 1950s, and ev­ery few years breed­ers bring out new va­ri­eties bet­ter adapted to the lat­est strain of fun­gus or bet­ter able to tol­er­ate drought or salt.

Noth­ing like this is pos­si­ble with any co­ral species – let alone the hun­dreds of Great Bar­rier Reef species one would want to as­sist. Van Op­pen and col­leagues are hop­ing to con­tract thou­sands of years of whea ttweak­ing ex­pe­ri­ence into a decade.

Their source of op­ti­mism lies in the fact that co­ral nat­u­rally has some tricks up its sleeve. On any bleached reef, some corals will sur­vive. The ques­tion is why.

It all comes down to ecosys­tems. A ma­ture co­ral head is a colony of mil­lions of ge­net­i­cally iden­ti­cal polyps – tiny, del­i­cate, anemone-like or­gan­isms that build lime­stone ‘houses’ around them­selves, which form the struc­ture of co­ral reefs. Ev­ery tiny pin­prick in the lime­stone is a place a liv­ing polyp calls home.

Each polyp houses an in­vis­i­ble com­mu­nity of di­verse mi­crobes within its body tis­sues. “Life did not take over the world by com­bat but by net­work­ing,” wrote evo­lu­tion­ary bi­ol­o­gist Lynn Mar­gulis. Corals take net­work­ing to a whole new level.

What that means is that re­searchers have to con­sider more than just the co­ral’s genes if they want to speed up their evo­lu­tion.

For starters, there are the genes of their most fa­mous co­hab­i­tants – var­i­ous types of sin­gle-celled al­gae, col­lec­tively known as zoox­an­thel­lae or the Sym­bio­dinium. Juvenile polyps swal­low these al­gae but in­stead of di­gest­ing them, they usher them into pur­pose-built com­part­ments within the outer cells of the polyp. Like all plants, al­gae make sugar from sun­light via a set of chem­i­cal re­ac­tions called pho­to­syn­the­sis and they pro­vide their co­ral host with 90% of its calo­rie re­quire­ments. That pow­ers the corals’ mon­u­men­tal lime­stone-building project wa­ters that are oth­er­wise low in nutri­ents. The need for sun­light is why corals are so vul­ner­a­ble to poor wa­ter qual­ity, which can smother the co­ral in sed­i­ment and block the sun.

But heat is the worst stress of all. When tem­per­a­tures stay high for more than a week or two, the vi­tal co­ral-al­gae part­ner­ship starts to break down. The heat plays havoc with the al­gae’s pho­to­syn­thetic re­ac­tions, caus­ing them to re­lease in­creased amounts of dam­ag­ing chem­i­cals called ox­i­dants. In the face of this toxic as­sault, the polyps be­gin evict­ing the res­i­dent Sym­bio­dinium. Some corals flu­o­resce a daz­zling shade of elec­tric blue in the process, per­haps an at­tempt to soak up the ex­ces­sive en­ergy of the ox­i­dants. But the show is short-lived. Once the al­gae are evicted, the tan brown colour of healthy co­ral bleaches to white. It is pos­si­ble for the polyps to be re­colonised; if they are not, the co­ral starves to death over a few weeks.

But evic­tion is not al­ways the out­come, and there’s ev­i­dence to sug­gest that the genes of the al­gae play a role in de­ter­min­ing how well the part­ner­ship sur­vives. For in­stance, back in 2006, van Op­pen and col­league Ray Berkel­mans trans­planted tem­per­a­ture-sen­si­tive corals from the Kep­pel is­lands to the warmer wa­ters of Mag­netic Is­land, 600 km fur­ther north. The corals that sur­vived had traded their old al­gal part­ners, Clade C, for the more heat-tol­er­ant Clade D types.

The Sym­bio­dinium part­ner­ship is cru­cial to the co­ral

If the Paris cli­mate ac­cord holds and emis­sions cease by 2050, the hope is that as­sisted evo­lu­tion will buy time for corals to adapt to 1– 2 de­grees of fur­ther warm­ing.

Worth try­ing to save?

04 | Madeleine van Op­pen has pi­o­neered re­search to speed up the evo­lu­tion of co­ral.

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