Reduced early life growth and survival in a fish in direct response to increased carbon dioxide

Absorption of anthropogenic carbon dioxide by the world's oceans is causing mankind's other CO ₂ problem', ocean acidification. Although this process will challenge marine organisms that synthesize calcareous exoskeletons or shells, it is unclear how it will affect internally calcifying organisms, such as marine fish. Adult fish tolerate short-term exposures to CO ₂ levels that exceed those predicted for the next 300 years (-2,000 ppm; ref. 8), but potential effects of increased CO ₂ on growth and survival during the early life stages of fish remain poorly understood. Here we show that the exposure of early life stages of a common estuarine fish (Menidia beryllina) to CO ₂ concentrations expected in the world's oceans later this century caused severely reduced survival and growth rates. When compared with present-day CO ₂ levels (∼1/4400ppm), exposure of M. beryllina embryos to ∼1/41,000ppm until one week post-hatch reduced average survival and length by 74% and 18%, respectively. The egg stage was significantly more vulnerable to high CO ₂ -induced mortality 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 adult-fish abundance.