Ocean Acidification Gives Young Fish a Death Wish

Changing ocean chemistry could turn some fish species into easy meals, with senses of smell so scrambled they’re actually attracted to their predators.

Researchers discovered the potentially deadly problem through a series of experiments on common reef-dwelling fish that were raised in seawater with acidity levels resembling what’s expected by the century’s middle and end.

“Instead of avoiding the odor of a predator, they’re attracted to it,” said biologist Douglas Chivers of the University of Saskatchewan. “When you take them into the wild, their behavior has changed. We ended up with huge mortality.”

When carbon dioxide dissolves in seawater, the concentration of hydrogen ions increases, making it more acidic. Global oceanic pH — the scale used to measure acids and bases — has changed by 0.1 in the last century. The number looks small, but in geological terms it’s a massive change, and Earth’s oceans are more acidic now than at any time in the last 650,000 years. Scientists say marine pH could change by another 0.3 by the year 2100.

Continue www.wired.com/wiredscience/2010/07/fish-death-wish/