Tropical tunas are largely consumed worldwide, providing major nutritional benefits to humans, but also representing the main exposure to methylmercury, a potent neurotoxin that biomagnifies along food webs. The combination of ecological tracers (nitrogen and carbon stable isotopes, δ¹⁵N and δ¹³C) to mercury concentrations in tunas is scarce yet crucial to better characterise the influence of tuna foraging ecology on mercury exposure and bioaccumulation. Given the difficulties to get modern and historical tuna samples, analyses have to be done on available and unique samples. However, δ¹³C values are often analysed on lipid-free samples to avoid bias related to lipid content. While lipid extraction with non-polar solvents is known to have no effect on δ¹⁵N values, its impact on mercury concentrations is still unclear. We used white muscle tissues of three tropical tuna species to evaluate the efficiency and repeatability of different lipid extraction protocols commonly used in δ¹³C and δ¹⁵N analysis. Dichloromethane was more efficient than cyclohexane in extracting lipids in tuna muscle, while the automated method appeared more efficient but as repeatable as the manual method. Lipid extraction with dichloromethane had no effect on mercury concentrations. This may result from i) the affinity of methylmercury to proteins in tuna flesh, ii) the low lipid content in tropical tuna muscle samples, and iii) the non-polar nature of dichloromethane. Our study suggests that lipid-free samples, usually prepared for tropical tuna foraging ecology research, can be used equivalently to bulk samples to document in parallel mercury concentrations at a global scale.

热带金枪鱼在世界范围内被大量食用，为人类提供了主要的营养益处，但也代表了甲基汞的主要暴露，甲基汞是一种沿食物网生物放大的强效神经毒素。将生态示踪剂（氮和碳稳定同位素，δ ¹⁵ N 和 δ ¹³ C）与金枪鱼中的汞浓度相结合是稀缺的，但对于更好地表征金枪鱼觅食生态对汞暴露和生物积累的影响至关重要。鉴于获得现代和历史金枪鱼样本的困难，必须对可用和独特的样本进行分析。然而，通常在无脂质样品上分析δ ¹³ C 值，以避免与脂质含量相关的偏差。虽然已知使用非极性溶剂提取脂质对 δ 没有影响¹⁵ N 值，其对汞浓度的影响尚不清楚。我们使用三种热带金枪鱼的白肌组织来评估 δ ¹³ C 和 δ ^{15 中}常用的不同脂质提取方案的效率和可重复性N 分析。在提取金枪鱼肌肉中的脂质方面，二氯甲烷比环己烷更有效，而自动化方法似乎更有效，但与手动方法一样具有可重复性。用二氯甲烷提取脂质对汞浓度没有影响。这可能是由于 i) 甲基汞对金枪鱼肉中蛋白质的亲和力，ii) 热带金枪鱼肌肉样品中的低脂质含量，以及 iii) 二氯甲烷的非极性性质。我们的研究表明，通常为热带金枪鱼觅食生态研究准备的无脂质样品可与大宗样品同等使用，以在全球范围内记录平行的汞浓度。