It seems like it’s always bad news for coral reefs. The ocean is acidifying, the Great Barrier Reef has experienced significant bleaching, and — if warming temperatures continue — 99 percent of reefs will be similarly damaged by the end of the century.
Desperate to help coral survive climate change, scientists have tried many strategies to improve reef resilience. They’ve developed marine-protected areas, built coral nurseries, and even started genetically engineering “super-corals” that can withstand bleaching.
But a new study from Duke University suggests that a simple, local intervention can give corals a big boost — by plucking off snails.
After a bleaching event, coral reefs are weakened and vulnerable to disease. Little aquatic creatures like snails and other small predators (“corallivores”) can make that recovery much more difficult.
A Duke University researcher compares corallivores to “Dracula, constantly sucking the energetic reserves out of corals.” Her team decided to see what would happen if they removed corallivores before an anticipated temperature spike.
The researcher, Elizabeth Shaver, recently published the results of that experiment in Nature Ecology & Evolution. She and her team tested their idea on corallivorous snails and brain corals in the Florida Keys in 2014.
The experiment was a success. Corals where snails were removed experienced 50 percent less bleaching than those with high snail densities. Shaver is hopeful that the finding will encourage reef managers to continue to take action locally.
“Climate change is the single greatest threat that faces coral reefs,” Shaver says. “But we still need to be working with managers to find local actions that they can do to help buy the reefs more time.”
Other researchers aren’t so sure. John Bruno, professor of biology at the University of North Carolina Chapel Hill, argues that while local interventions may work in a controlled or limited environment, they don’t carry over to large-scale policy.
“When people actually test the policy, in a way that a manager would do it — it never works,” he told me over the phone. “I don’t really see there being a policy where scientists remove snails from the Great Barrier Reef. It’s just impractical.”
He admits that it’s difficult to balance the harsh realities of climate change with the desire for hope and positivity. “For me, it’s only about climate mitigation,” he says, echoing many scientists who have argued that swift climate action is the only way to save reefs. “But I hate to be another scientist just talking about gloom and doom.”
We need to move quickly in order to protect the “rainforests of the sea.” But we might want to pick off some corallivores on the way.