Biological fitness relies on processes acting at various levels of organization, all of which can be modified by environmental change. Application of synthesis frameworks, such as the Adverse Outcome Pathway (AOP), can enhance our understanding of the responses to stressors identified in studies at each level, as well as the links among them. However, the use of such frameworks is often limited by a lack of data. In order to identify contexts with sufficient understanding to apply the AOP framework, we conducted a meta-analysis of studies considering ocean acidification effects on calcifying mollusks. Our meta-analysis identified that most studies considered the adult life history stage, bivalve taxonomic group, individual-level changes, and growth- and metabolism-related responses. Given the characteristics of the published literature, we constructed an AOP for the effects of ocean acidification on calcification in an adult bivalve, specifically the Pacific oyster (Magallana gigas). By structuring results within the AOP framework, we identify that, at present, the supported pathways by which ocean acidification affects oyster calcification are via the downregulation of cavortin and arginine kinase transcription. Such changes at the molecular level can prompt changes in cellular and organ responses, including altered enzyme activities, lipid peroxidation, and regulation of acid–base status, which have impacts on organism level metabolic rate and, therefore, calcification. Altered calcification may then impact organism mortality and population sizes. We propose that when developed and incorporated in future studies, the AOP framework could be used to investigate sources of complexity including varying susceptibility within and among species, feedback mechanisms, exposure duration and magnitude, and species interactions. Such applications of the AOP framework will allow more effective reflections of the consequences of environmental change, such as ocean acidification, on all levels of biological organization.

中文翻译：

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太平洋牡蛎如何应对海洋酸化：基于元分析的不利结果途径的开发和应用

生物适应性依赖于组织不同层次的过程，所有这些过程都可以通过环境变化来改变。综合框架的应用，如不良结局途径 (AOP)，可以增强我们对每个级别研究中确定的压力源反应的理解，以及它们之间的联系。然而，此类框架的使用通常受到缺乏数据的限制。为了确定具有充分理解以应用 AOP 框架的背景，我们对考虑海洋酸化对钙化软体动物的影响的研究进行了荟萃分析。我们的荟萃分析发现，大多数研究都考虑了成年生活史阶段、双壳类动物分类群、个体水平的变化以及与生长和代谢相关的反应。鉴于已发表文献的特点，我们构建了一个 AOP，用于研究海洋酸化对成年双壳类动物钙化的影响，特别是太平洋牡蛎 (Magallana gigas)。通过在 AOP 框架内构建结果，我们确定，目前，海洋酸化影响牡蛎钙化的支持途径是通过下调 cavortin 和精氨酸激酶转录。这种分子水平的变化会促使细胞和器官反应发生变化，包括酶活性的改变、脂质过氧化和酸碱状态的调节，这些都会影响生物体水平的代谢率，从而影响钙化。改变的钙化可能会影响生物体死亡率和种群规模。我们建议，当开发并纳入未来的研究时，AOP 框架可用于调查复杂性的来源，包括物种内部和物种之间的不同敏感性、反馈机制、暴露持续时间和强度以及物种相互作用。AOP 框架的这种应用将允许更有效地反映环境变化的后果，例如海洋酸化，在生物组织的各个层面上。