Their inner ears turn wonky when they grow up in carbon-rich water, which could keep juveniles from finding their way to the reefs. That could mean trouble.
AN IMMOBILIZED FISH lay between Craig Radford’s fingers. The several-week-old Australasian snapper, no longer than a pinkie nail, rested flat on a slab of modeling clay, held down by small staples—“as someone would strap you down on an ambulance bed to hold you there,” says Radford. He stuck tiny electrodes on the fish’s head, then submerged it in a tank and switched on an underwater speaker. It was time to test its hearing.
“If you actually put your head underwater and take the time to listen, it’s amazing what you’ll hear,” Radford says. “From whales to fish to crustaceans—sound plays an important role in many, many different species’ life strategies.”
But Radford’s experiment wasn’t due to curiosity about what the world sounds like to fish. He was worried about how well they could hear it.