By Janet Raloff
A new study may explain how rising carbon dioxide concentrations — and the ocean acidification they induce — can cause topsy-turvy changes in the behavior of fish. Like a flipped switch, the normal response of nerve cells can reverse as acidifying seawater perturbs how a fish regulates acids and bases in its body, including the brain.
“This could be a big deal,” says neurobiologist Andrew Dittman of the National Oceanic and Atmospheric Administration’s Northwest Fisheries Science Center in Seattle. Dittman, who was not affiliated with the study, says the new findings could go a long way toward explaining curious sensory changes observed in fish exposed to acidifying waters. The scary scent of predators, for example, can suddenly become alluring.
For the new study, published online January 15 in Nature Climate Change, Göran Nilsson of the University of Oslo and his colleagues homed in on brain chemistry.
The idea emerged after Philip Munday of James Cook University in Townsville, Australia, told Nilsson of behavioral quirks his laboratory fish were exhibiting in a high–carbon dioxide environment — conditions exemplifying ocean waters a half-century or more from now. Nilsson, a neurophysiologist, speculated that a connection between nerves and chemistry might be involved. “It was very much an ‘Aha’ moment,” Munday says.