Elevated pCO2 causes developmental delay in early larval Pacific oysters, Crassostrea gigas

Increasing atmospheric CO2 equilibrates with surface seawater, elevating the concentration of aqueous hydrogen ions. This process, ocean acidification, is a future and contemporary concern for aquatic organisms, causing failures in Pacific oyster (Crassostrea gigas) aquaculture. This experiment determines the effect of elevated pCO2 on the early development of C. gigas larvae from a wild Pacific Northwest population. Adults were collected from Friday Harbor, Washington, USA (48°31.7' N, 12°1.1' W) and spawned in July 2011. Larvae were exposed to Ambient (400 µatm CO2), MidCO2 (700 µatm), or HighCO2 (1,000 µatm). After 24 h, a greater proportion of larvae in the HighCO2 treatment were calcified as compared to Ambient. This unexpected observation is attributed to increased metabolic rate coupled with sufficient energy resources. Oyster larvae raised at HighCO2 showed evidence of a developmental delay by 3 days post-fertilization, which resulted in smaller larvae that were less calcified.大气中浓度持续升高的二氧化碳会与表层海水达成平衡，进而提升海水中氢离子的浓度。这一过程即为海洋酸化（ocean acidification），当前与未来均会对水生生物造成危害，并导致太平洋牡蛎（Crassostrea gigas）养殖业出现失败案例。本实验旨在探究二氧化碳分压（pCO2）升高对采自西北太平洋野生种群的太平洋牡蛎幼体早期发育的影响。实验所用成体采自美国华盛顿州星期五港（48°31.7' N, 12°1.1' W），并于2011年7月完成产卵繁育。实验将幼体分为三组，分别置于环境对照组（400 µatm 二氧化碳）、中等二氧化碳组（700 µatm）及高二氧化碳组（1000 µatm）中培养。培养24小时后，高二氧化碳组中完成钙化的幼体比例显著高于环境对照组。该意外观测结果可归因于代谢速率提升与充足能量供给的共同作用。而在高二氧化碳环境中培育的牡蛎幼体，在受精后3天便表现出发育延迟现象，最终导致幼体体型更小、钙化程度更低。