Saving Coral: Evolution in the Lab

Photo Credit: Jim Maragos, U.S. Fish and Wildlife Service

Beyond their beauty that draws tourists from around the world, coral reefs are extraordinary ecosystems. Approximately one quarter of all ocean species depend on coral reefs for food and shelter. But nature can’t seem to keep up with the destruction brought on by climate change. The world’s coral reefs are especially sensitive to changes in water temperature and acidity. According to the Global Coral Reef Monitoring Network, an international initiative dedicated to coral reef preservation, 20% of the monitored reefs around the world have been destroyed in the last 50 years. The Great Barrier Reef alone has lost half its coral cover to acidifying and warming waters in the last 30 years.

But there may be hope for these reef builders. Using a technique called assisted evolution, researchers are breeding so-called “supercoral” that can withstand the harsh conditions of climate change. But, this technique leaves some scientists wondering how scientific intervention can do what Mother Nature can’t.

The concept of assisted evolution is pretty straightforward. By specifically cross-breeding certain organisms, breeders can pass on a desired trait. It’s nothing new – farmers have been using it for centuries to breed plants to resists pests or animals to grow bigger and faster. For example, scientists crossbred tomatoes since the beginning of the 20th century to select for size and shape, among other factors.

Dr. Madeleine van Oppen, a senior principal research scientist at the Australian Institute of Marine Science, began her career by thinking about how this selective crossbreeding technique could be used to help coral populations. As she read more broadly about resilient coral, she brought her theories into practice.

In her lab, van Oppen gradually exposes the coral to extreme conditions like warm or acidic water. She exposes those coral that survive to even harsher conditions until, eventually, she and her colleagues will create a “supercoral”, more resilient to the threatening conditions of climate change than any native species. They want to reintegrate the supercoral into the wild with native coral, in the hopes of boosting the resilience of the entire population. That is, if it can be done at all. The team has just begun breeding the coral in a laboratory setting, but it will be several years before they will know if they’ve created a “supercoral”.

In order for selective breeding to be possible, the desired trait must be heritable. In other words, coral must be able to pass on the ability to tolerate heat to their offspring. Preliminary research suggests a genetic response to temperature exists in coral. Faced with an extreme environment, the coral might naturally adapt to heat and acidity – over many generations. But, according to van Oppen, the waters are warming too quickly to let Nature take its course. One generation of wild coral can last for a hundred years before they need to breed.

While the idea of breeding “supercoral” has some researchers eager to take part, others point out potential limitations. Some researchers worry that the new supercoral will out-compete the native coral and become an invasive species. Leslie Kaufman, a marine biology professor and researcher from Boston University who has been studying coral resilience for decades, says ecologists cannot save the reefs with assisted evolution alone.

“There isn’t a blueprint that says here’s how to make this coral reef. Instead, it’s a history,” said Kaufman. “It’s a result of organisms weaving themselves together and it takes about 15 or 20 years to produce this fabric of living reef that then continues to grow for thousands of years.”

Kaufman also studies the genes that make coral species resilient. His lab focuses on the natural abilities coral colonies use to defend themselves from the ocean’s increasingly harsh environment. He argues that it is unrealistic to think that replanting “supercoral” will solve the entire problem.

Kaufman says that the most crucial thing to do is to put an end to the practices that endanger coral. As people flock to coastlines, often to enjoy the beauty of wildlife, they produce waste like sewage and litter that is toxic to coral. Our SUVs and carbon-powered lifestyles certainly don’t help. Over the past fifty years the ocean absorbed about 20 times as much heat as the atmosphere, largely due to the burning of fossil fuels. Coral reefs are also being destroyed for commercial uses, like collecting shells to sell to tourists.

If we don’t stop ripping the reef apart to make a living, says Kaufman, coral conservation doesn’t stand a chance. But he is hopeful that with increasing awareness, scientific collaboration, and the urgent action of policy-makers, the coral reefs can survive.

“We have to look at this as a therapy of the entire patient,” said Kaufman, “not just cutting its fingernails.”

For Kaufman, it’s a matter of conservation principles – addressing the root cause of a decades-old problem.




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