Lifetime Chronicles of Selenium Exposure Linked to Deformities in an Imperiled Migratory Fish

Aquatic ecosystems
worldwide face growing threats from elevated
levels of contaminants from human activities. Toxic levels of selenium
(Se) shown to cause deformities in birds, fish, and mammals can transfer
from parents to progeny during embryonic development or accumulate
through Se-enriched diets. For migratory species that move across
landscapes, tracking exposure to elevated Se is vital to mitigating
vulnerabilities. Yet, traditional toxicological investigations resolve
only recent Se exposure. Here, we use a novel combination of X-ray
fluorescence microscopy and depositional chronology in a biomineral
to reveal for the first time provenance, life stage, and duration
of toxic Se exposure over the lifetime of an organism. Spinal deformities
observed in wild Sacramento Splittail (Pogonichthys
macrolepidotus), an imperiled migratory minnow, were
attributed to elevated Se acquired through maternal transfer and juvenile
feeding on contaminated prey. This novel approach paves the way for
diagnosing sources, pathways, and potential for a cumulative exposure
of Se relevant for conservation.

全球水生生态系统正面临人类活动引发的污染物浓度升高所带来的愈发严峻的威胁。具有毒性浓度的硒（Selenium, Se）已被证实可导致鸟类、鱼类及哺乳动物出现畸形，该物质可在胚胎发育阶段由亲代传递给子代，或通过富含硒的膳食在生物体内累积。对于跨区域迁徙的物种而言，追踪其暴露于高浓度硒的情况，对缓解其生存风险至关重要。然而，传统毒理学研究仅能检测到生物近期的硒暴露事件。本研究首次结合X射线荧光显微镜（X-ray fluorescence microscopy）与生物矿化物中的沉积年代学方法，揭示了生物整个生命周期内暴露于毒性硒的来源、所处生命阶段及持续时长。研究人员在受威胁的迁徙性小型鱼类——野生萨克拉门托裂尾鱼（*Pogonichthys macrolepidotus*）中观察到脊柱畸形，该畸形被归因于其通过母体传递以及幼体取食受污染猎物而摄入的高浓度硒。这一创新方法为诊断与物种保护相关的硒暴露来源、暴露路径及累积暴露潜力提供了全新的技术路径。