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
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”