Exposure of early life stages of a common estuarine fish (inland silverside) to ocean acidification conditions expected in the world’s oceans later this century reduced survival by 74 percent and growth by 18 percent. The egg stage was significantly more vulnerable than the post-hatch larval stage. These findings challenge the belief that ocean acidification will not affect fish populations, because even small changes in early life survival can generate large fluctuations in abundance of adult fish. (Laboratory study)