1 Laboratoire d'Océanographie de Villefranche, Sorbonne Université, CNRS , 181 chemin du Lazaret, 06230 Villefranche-sur-mer , France.
3 Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, DISTAV , Università di Genova, Genova , Italy.
Proc Biol Sci. 2018 Dec 19;285(1893):20182381. doi: 10.1098/rspb.2018.2381.
Coastal marine ecosystems experience dynamic fluctuations in seawater carbonate chemistry. The importance of this variation in the context of ocean acidification requires knowing what aspect of variability biological processes respond to. We conducted four experiments (ranging from 3 to 22 days) with different variability regimes (pH 7.4-8.1) assessing the impact of diel fluctuations in carbonate chemistry on the early development of the mussel Mytilus galloprovincialis. Larval shell growth was consistently correlated to mean exposures, regardless of variability regimes, indicating that calcification responds instantaneously to seawater chemistry. Larval development was impacted by timing of exposure, revealing sensitivity of two developmental processes: development of the shell field, and transition from the first to the second larval shell. Fluorescent staining revealed developmental delay of the shell field at low pH, and abnormal development thereof was correlated with hinge defects in D-veligers. This study shows, for the first time, that ocean acidification affects larval soft-tissue development, independent from calcification. Multiple developmental processes additively underpin the teratogenic effect of ocean acidification on bivalve larvae. These results explain why trochophores are the most sensitive life-history stage in marine bivalves and suggest that short-term variability in carbonate chemistry can impact early larval development.
沿海海洋生态系统经历着海水碳酸盐化学的动态波动。在海洋酸化的背景下，这种变化的重要性需要知道生物过程对变化的哪个方面做出反应。我们进行了四项实验（持续时间从 3 天到 22 天不等），具有不同的变化规律（pH 值 7.4-8.1），评估了碳酸盐化学昼夜波动对贻贝 Mytilus galloprovincialis 早期发育的影响。幼虫壳生长始终与平均暴露相关，而与变化规律无关，这表明钙化对海水化学物质的反应是即时的。幼虫发育受到暴露时间的影响，揭示了两个发育过程的敏感性：壳域的发育以及从第一壳到第二壳的转变。荧光染色显示低 pH 值下壳域发育延迟，并且在 D 幼虫中与此处的铰链缺陷相关联。这项研究首次表明，海洋酸化会影响幼虫的软组织发育，而与钙化无关。多个发育过程共同构成海洋双壳类幼虫海洋酸化致畸作用的基础。这些结果解释了为什么担轮幼虫是海洋双壳类动物中最敏感的生活史阶段，并表明短期碳酸盐化学变化会影响早期幼虫发育。
