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

Focus-Science and Technology - - Cover Story -

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 ev­er­ex­pand­ing 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.

“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”

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