Seawater carbonate chemistry, length and survival of Inland silverside, Menidia beryllina, during experiments, 2012@en

Absorption of anthropogenic carbon dioxide by the world's oceans is causing mankind's 'other CO2 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 CO2 levels that exceed those predicted for the next 300 years (~2,000 ppm), but potential effects of increased CO2 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 CO2 concentrations expected in the world's oceans later this century caused severely reduced survival and growth rates. When compared with present-day CO2 levels (~400 ppm), exposure of M. beryllina embryos to ~1,000 ppm until one week post-hatch reduced average survival and length by 74% and 18%, respectively. The egg stage was significantly more vulnerable to high CO2-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.

全球海洋吸收人为二氧化碳（anthropogenic carbon dioxide）正引发人类的“另一项二氧化碳难题”——海洋酸化（ocean acidification）。尽管这一过程会对合成钙质外骨骼/贝壳（calcareous exoskeletons or shells）的海洋生物构成生存挑战，但目前尚不清楚其会对体内钙化生物（internally calcifying organisms）造成何种影响，例如海洋鱼类。成年鱼类可耐受短期暴露于远超未来300年预测浓度（约2000ppm）的二氧化碳环境中，但二氧化碳浓度升高对鱼类早期生命阶段的生长与存活所产生的潜在影响，仍未得到充分解析。本研究显示，将一种常见河口鱼类——大西洋银汉鱼（Menidia beryllina）——的早期生命阶段暴露于本世纪末全球海洋预计将达到的二氧化碳浓度环境中，会显著降低其存活率与生长速率。与当前二氧化碳水平（约400ppm）相比，将大西洋银汉鱼（M. beryllina）胚胎暴露于约1000ppm的环境中直至孵化后一周，其平均存活率与体长分别下降了74%与18%。相较于孵化后的幼体阶段，鱼卵阶段对高二氧化碳诱导的死亡更为敏感。本研究结果挑战了“海洋酸化不会影响鱼类种群”的固有认知，因为早期生命阶段存活率的细微变化，即可引发成鱼种群丰度的大幅波动。