More carbon dioxide emissions lead to more CO2 dissolving in the oceans, which turns the water acidic. Those sour seas slow the growth of corals. And it turns out acidic seawater also makes clownfish and damselfish suicidally bold and reckless, according to a study in the Proceedings of the National Academy of Sciences.
Researchers used IPCC estimates of future CO2 emissions to mix up seawater with varying degrees of acidity, similar to what we might see in 50 to 100 years. Fish larvae raised on the most acidic batch of seawater instinctively avoided predators at first, but soon were actually attracted to the predator's scent—probably due to some impairment of the olfactory system.
When those same fish were placed in experimental reefs near the Great Barrier Reef, they disregarded safety, straying from the protective coral. And cruising predators snatched up nearly all of them within 30 hours. Over the same period, only 10 percent of the fish raised in seawater of today’s acidity were eaten.
A disruption as big as climate change is bound to challenge numerous species. This study suggests that some challenges will be as unexpected as a cunning predator.
—Christopher Intagliata
