Munday L., Cheal A. L., Dixson D. L., Rummer J. L. & Fabricius K. E., 2014. Behavioural impairment in reef fishes caused by ocean acidification at CO2 seeps. Nature Climate Change 4:487-492.
In Finding Nemo, the despondent protagonist Nemo wanders away from a school fieldtrip after his father Marlin mocks his impaired swimming ability, the result of a congenital lame fin. At least that is Pixar’s take on what happened. Science might say it was something in the water that emboldened the little talking clownfish to leave the safety of his reef to embark on a feature length adventure of a lifetime.
That something might have been carbon dioxide, the main culprit of ocean acidification, and prime suspect in anthropogenic climate change. When atmospheric carbon dioxide dissolves in water, it equilibrates to form carbonic acid. Acidification due to dissolved carbon dioxide is the same reason your dentist might have told you to avoid carbonated beverages. Sugar aside, just like the carbonation in a can of soda weakens your teeth, increases in acidity (decreases in pH) due to dissolved carbon dioxide can compromise coral structure, or otherwise alter the physiology of, for example, Nemo.
A study recently published by Munday et al. in Nature Climate Change suggests that reef fish exposed to higher levels of carbon dioxide exhibit reckless and vagrant behavior as compared to their more conservative counterparts in waters with lower concentrations of carbon dioxide. Past studies meant to simulate the effects of ocean acidification on fish behavior have shown that elevated exposure to the greenhouse gas desensitizes laboratory-reared fish to danger, such as predation. However, the question remains: how are native ecological communities affected by behavioral changes due to continuous exposure to elevated levels of carbon dioxide?