1. Ocean acidification by anthropogenic carbon dioxide emissions is projected to depress metabolic and physiological activity in marine calcifiers. To evaluate the sensitivity of marine organisms against ocean acidification, the assimilation of nutrients into carbonate shells and soft tissues must be examined.
2. We designed a novel experimental protocol, reverse radioisotope labelling, to trace partitioning of nutrients within a single bivalve species under ocean acidification conditions. Injecting CO₂ gas, free from radiocarbon, can provide a large contrast between carbon dissolved in the water and the one assimilated from atmosphere. By culturing modern aquifer organisms in acidified seawater, we were able to determine differences in the relative contributions of the end members, dissolved inorganic carbon (DIC) in seawater and metabolic CO₂, to shell carbonate and soft tissues.
3. Under all pCO₂ conditions (463, 653, 872, 1,137 and 1,337 μatm), radiocarbon (Δ¹⁴C) values of the bivalve Scapharca broughtonii shell were significantly correlated with seawater DIC values; therefore, shell carbonate was derived principally from seawater DIC. The Δ¹⁴C results together with stable carbon isotope (δ¹³C) data suggest that in S. broughtonii shell δ¹³C may reflect the kinetics of isotopic equilibration as well as end‐member contributions; thus, care must be taken when analysing end‐member contributions by a previous method using δ¹³C. The insensitivity of S. broughtonii to perturbations in pCO₂ up to at least 1,337 µatm indicates that this species can withstand ocean acidification.
4. Usage of radioisotope to dope for tracer experiments requires strict rules to conduct any operations. Yet, reverse radioisotope labelling proposing in this study has a large advantage and is a powerful tool to understanding physiology of aquifer organisms that can be applicable to various organisms and culture experiments, such as temperature, salinity and acidification experiments, to improve understanding of the proportions of nutrients taken in by marine organisms under changing environments.

中文翻译：

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新型反向放射性同位素标记实验揭示了海洋酸化条件下海洋钙化剂的碳同化

1. 人为排放的二氧化碳会导致海洋酸化，预计会降低海洋钙化剂的代谢和生理活性。为了评估海洋生物对海洋酸化的敏感性，必须检查养分在碳酸盐壳和软组织中的吸收情况。
2. 我们设计了一种新颖的实验方案，即反向放射性同位素标记，以在海洋酸化条件下追踪单个双壳类物种内营养物质的分配。注入不含放射性碳的CO ₂气体可以使溶解在水中的碳与从大气中吸收的碳之间具有很大的反差。通过在酸化海水中培养现代含水层生物，我们能够确定末端成员，海水中的溶解性无机碳（DIC）和代谢性CO ₂对壳碳酸盐和软组织的相对贡献的差异。
3. 下的所有p CO ₂条件下（463，653，872，1137和1337μatm），放射性碳（Δ ¹⁴ C）的双壳的值魁broughtonii壳被显著与海水DIC值相关联; 因此，壳层碳酸盐主要来自海水DIC。的Δ ¹⁴ C酶切连同稳定碳同位素（δ ¹³ C）的数据表明，在S. broughtonii壳δ ¹³ C可以反映同位素平衡以及端部件的贡献的动力学; 因此，通过使用δ的先前方法分析最终构件的贡献时必须小心，¹³ C的不敏感性S. broughtonii对p CO _2的扰动至少达到1,337 µatm，表明该物种可以承受海洋酸化。
4. 使用放射性同位素对示踪剂实验进行掺杂需要严格的规则才能进行任何操作。然而，这项研究中提出的反向放射性同位素标记具有很大的优势，并且是了解含水层生物生理的有力工具，可用于各种生物和培养实验，例如温度，盐度和酸化实验，以增进对比例的了解在变化的环境中海洋生物吸收的营养素。