THE CORAL MATCHMAKER

We’re in the midst of a mass ex­tinc­tion event. Jamie Craggs hopes his re­search could save coral reefs from this fate

BBC Earth (Asia) - - Science -

“Sure enough, at 1pm, the spec­ta­cle be­gins. In dark­ened tanks, thou­sands of tiny pink spheres, each no larger than a sugar gran­ule, are re­leased by the coral and float to the sur­face”

It’s not a good time to be a wild an­i­mal or plant. Ex­tinc­tion rates are soar­ing. Ev­ery day, up to 100 species are lost for­ever, and it’s es­ti­mated that around 25,000 species are tee­ter­ing on the edge of obliv­ion. We live in a time of mass ex­tinc­tion, and nowhere is safe. In the oceans, it’s thought that 60 per cent of the world’s coral reefs could die over the next 20 years.

It’s not all bad news, how­ever. Species can, and have, been res­cued from the brink of ex­tinc­tion, and some­times their saviours can be found in the most un­ex­pected of places, like the bow­els of a south Lon­don mu­seum. Jamie Craggs, the aquar­ium cu­ra­tor at the Horn­i­man Mu­seum and Gar­dens, is brim­ming with ex­cite­ment be­cause, very soon, the mini coral reefs he has so lov­ingly cre­ated will ex­plode with po­ten­tial new life. It’s the re­sult of five years’ hard graft, work­ing out the ex­act con­di­tions needed to make cap­tive coral spawn.

In the wild, corals like the ones Craggs is work­ing on re­pro­duce once a year, all on the same night and at the same time. The process, called syn­chro­nous spawn­ing, sees coral colonies re­lease clouds of sperm and eggs into the wa­ter, where they are min­gled and dis­persed by the waves and cur­rents. It’s an evo­lu­tion­ary adap­ta­tion that en­ables the sex cells of dis­tant coral colonies to meet and mix, min­imis­ing the risk of in­breed­ing.

In­side coral cells are al­gae-like or­gan­isms called sym­bi­otic zoox­an­thel­lae, which give them en­ergy and colour. But ris­ing sea tem­per­a­tures are caus­ing the zoox­an­thel­lae to desert the corals, leav­ing them bleached and sus­cep­ti­ble to dis­ease. The sur­vivors find them­selves so iso­lated that suc­cess­ful sex­ual re­pro­duc­tion is be­com­ing dif­fi­cult.

As part of his PhD at the Uni­ver­sity of Derby, Craggs has de­vised a closed tank sys­tem that mim­ics the nat­u­ral en­vi­ron­ment of corals. By con­trol­ling the type and du­ra­tion of light, along with nu­tri­ent lev­els, wa­ter chem­istry and tem­per­a­ture, he can re­li­ably and pre­dictably in­duce coral spawn­ing to within half an hour. “It’s a game changer,” he says. “No one else has ever been able to do that be­fore.”

When the spec­ta­cle be­gins, thou­sands of tiny pink spheres, each no larger than a sugar gran­ule, are re­leased by the coral and float to the sur­face of their dark­ened tanks. These par­tic­u­lar corals are hermaphrodites, so each pack­age con­tains both eggs and sperm. In a UK first, Craggs and his col­leagues have used them for in vitro fer­til­i­sa­tion (IVF), yield­ing new coral young. “The po­ten­tial is huge,” Craggs says. “We can now make the coral in our col­lec­tion spawn four or five times a year.” The only lim­it­ing fac­tors are the num­ber of tanks and the amount of time that Craggs and his team have.

As the young corals grow and form new colonies, they pro­vide an ever-ex­pand­ing re­source for sci­en­tific study. In the wild, some corals are nat­u­rally more re­sis­tant to ris­ing tem­per­a­tures, dis­ease and pol­lu­tion. With his new sys­tem, Craggs has the per­fect setup to iden­tify the fea­tures that en­dow these sto­ical in­di­vid­u­als with their re­silient na­ture. He can model how dif­fer­ent corals are likely to re­spond to fu­ture en­vi­ron­men­tal change, and crit­i­cally, he hopes to breed spe­cific in­di­vid­u­als to­gether to boost lev­els of ge­netic di­ver­sity, pro­duc­ing ro­bust corals that are more likely to sur­vive.

For eth­i­cal and prac­ti­cal rea­sons, Craggs’s corals will never be ex­ported, so last year, the mu­seum teamed up with The Florida Aquar­ium’s Cen­tre for Con­ser­va­tion. Us­ing tech­nol­ogy from the Horn­i­man Mu­seum’s Project Coral, the aquar­ium plans to breed hardy na­tive coral that will be used to di­rectly re­stock the de­pleted Florida Reef Tract. Af­ter that, who knows? There’s no rea­son why the same tech­niques can’t be rolled out to other ail­ing reefs, giv­ing the world’s coral and the myr­iad crea­tures that de­pend on it the chance of a brighter, more colour­ful fu­ture.

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