Crawford Drury, a coral ecologist and principal investigator of the Coral Resilience Lab at Hawaiʻi Institute of Marine Biology, is working to selectively breed coral. This involves selecting wild corals that have desirable genetic traits – such as the ability to survive high ocean temperatures – and then cross-breeding them to produce offspring with a better chance of withstanding the effects of climate change on their habitat.
In the past few decades, over half of the world’s coral reefs have died. And, according to a climate assessment by the UN, they are projected to decline by between 70 and 90 per cent within the century – even if global warming is kept to the 1.5 degrees Celsius target outlined in the 2016 Paris Agreement. Mass bleaching events – a stress reaction in corals that weakens and sometimes kills them – are growing in frequency. Ocean acidification, pollution, storms, disease and overfishing are putting these ecosystems through the ringer.
Despite covering less than one per cent of the world’s oceans, coral reefs – dubbed the rainforests of the sea – are home to almost a quarter of marine species. Millions of people rely on them for income from tourism and fisheries, as a source of food and new medicines, and for protection against coastline erosion. They also hold important cultural value for indigenous peoples.
Drury’s lab is a continuation of the work of its founder, Ruth Gates, who died in 2018. Around seven years ago, Gates teamed up with Madeleine Van Oppen, a coral geneticist at the Australian Institute of Marine Science (AIMS), and together they pioneered a concept known as assisted evolution, at a time when this was still widely considered a fringe concept. “Most of our work revolves around trying to understand and harness natural processes that are already happening, and leverage some of the actual mechanisms that nature already has to deal with change,” says Drury. His team collects eggs and sperm from coral colonies they know to be heat tolerant, puts them in little tubes and cross-fertilises them with other coral species, which in turn produces coral larvae with these traits. The hope is to use these corals to restore reefs that have been damaged.
Van Oppen’s group, meanwhile, is focusing on breeding more heat-tolerant algae that could be introduced to the coral. In a 2020 study, her team showed that corals created in this fashion were up to 26 times more likely to survive extreme heat than others. Her lab is also exploring the use of probiotics on coral reefs to help them withstand rising temperatures. “I'm hopeful that we'll wind up producing some tools and knowledge that helps us to avert the impending disaster,” she says.
Not everyone is so sure it will work. One criticism is that we don't know what consequences messing with coral genetics could have on species diversity. Another is its scalability. But these concerns are getting ahead of themselves, says Drury: the problem is so acute that if we don't act now, the coral reefs will die. “If you're facing this freight train of climate change and all those stressors, you might not be left with a lot to deal with or work with in the end anyway.”
Both Drury and Van Oppen stress that assisted evolution is just an interim solution to buy time for the reefs. To truly save them, the root cause – climate change – needs to be addressed. “It’s like a Band-Aid,” says Van Oppen. “You can hopefully deal with the symptoms for a while. But then if you don't actually remove the cause, in the long-term, it's not going to be enough.”
This article was originally published by WIRED UK
