汞(Hg)同位素数据的准确解释需要考虑几个生物因素,例如年龄,饮食,地理范围,和组织代谢更新。关于猎物-捕食者同位素掺入率和汞生物放大的先验知识至关重要。这项研究旨在评估汞稳定同位素在北极光虫物种中的掺入,带帽的海豹Cstophoracristata,保持在人类护理24个月(2012年至2014年),并以挪威春季产卵鲱鱼丛茎harengus的恒定饮食为食。我们测量了THg,MMHg和iHg水平,以及带帽海豹肾脏中具有质量依赖性(MDF)和质量无关(MIF)分馏的汞稳定同位素组成(例如δ202Hg和Δ199,200,201,204Hg),肝脏,头发和肌肉,除了鲱鱼肌肉。然后,我们计算了带帽海豹与其猎物之间的HgMDF和MIF同位素分馏。我们发现连帽海豹毛(0.80‰)和肾脏(-0.78‰)之间的δ202Hg显着变化,和鲱鱼肌肉。在带帽海豹组织中,δ202Hg与MMHg百分比呈正相关。这些发现表明,组织特异性Hg形态是这种北极捕食者中Hg同位素分馏率变化的主要驱动因素。Δ199Hg,Δ200Hg,鲱鱼和带帽海豹组织之间的Δ201Hg和Δ204Hg值没有变化,确认它们在顶级捕食者中作为汞海洋和大气来源的示踪剂的效用。据我们所知,这是首次尝试评估北极光虫内部系统中复杂的汞同位素动力学,控制年龄的影响,饮食,和分配。我们的结果证实了汞稳定同位素作为环境汞来源示踪剂的有效性,即使在顶级捕食者中,但强调动物年龄和组织选择对于研究间和物种间比较的重要性。
Accurate interpretation of mercury (Hg) isotopic data requires the consideration of several biotic factors such as age, diet, geographical range, and tissue metabolic turnover. A priori knowledge of prey-predator isotopic incorporation rates and Hg biomagnification is essential. This study aims to assess Hg stable isotopes incorporation in an Arctic species of Phocidae, the hooded seal Cystophora cristata, kept in human care for 24 months (2012-2014) and fed on a constant diet of Norwegian Spring Spawning herring Clupea harengus. We measured THg, MMHg and iHg levels, as well as Hg stable isotope composition with both mass dependent (MDF) and mass independent (MIF) fractionation (e.g. δ202Hg and Δ199,200,201,204Hg) in hooded seal kidney, liver, hair and muscle, in addition to herring muscle. We then calculated Hg MDF and MIF isotopic fractionation between hooded seals and their prey. We found a significant shift in δ202Hg between hooded seal hair (+0.80‰) and kidney (-0.78‰), and herring muscle. In hooded seals tissues δ202Hg correlated positively with MMHg percentage. These findings suggest that tissue-specific Hg speciation is the major driver of changes in Hg isotopic fractionation rates in this Arctic predator. Δ199Hg, Δ200Hg, Δ201Hg and Δ204Hg values did not vary between herring and hooded seal tissues, confirming their utility as tracers of Hg marine and atmospheric sources in top predators. To our knowledge, this represents the first attempt to assess complex Hg isotope dynamics in the internal system of Arctic Phocidae, controlling the effects of age, diet, and distribution. Our results confirm the validity of Hg stable isotopes as tracers of environmental Hg sources even in top predators, but emphasize the importance of animal age and tissue selection for inter-study and inter-species comparisons.