Listen up! Carbon dioxide being absorbed by the oceans is having a puzzling effect on fish -- their ears get bigger.
The ear structure in fish, known as an otolith, is made up of minerals. Scientists knew that increasing carbon dioxide in the oceans -- absorbed from the atmosphere -- is making the sea more acidic, which can dissolve and weaken shells. They wondered if it also would reduce the size of the otoliths.
It turned out to be just the opposite, according to a study published Friday in the journal Science.
Biological oceanographer David M. Checkley of the Scripps Institution of Oceanography at UC San Diego and colleagues incubated the eggs of white sea bass in seawater and measured the otoliths when the fish were 7 to 8 days old.
In the first test, the water had more than six times the usual amount of carbon dioxide, and the little fish grew otoliths 15% to 17% larger than normal. The surprised researchers repeated the experiment and got the same results.