Sinclair Cailin A, Garcia Tiffany S, Vasta Rachel, Eagles-Smith Collin A
Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University, Corvallis, OR, United States.
Department of Integrative Biology, Oregon State University, Corvallis, OR, United States.
Environ Toxicol Chem. 2025 Jul 1;44(7):1824-1834. doi: 10.1093/etojnl/vgaf100.
Mercury bioavailability and biomagnification in freshwater systems can be highly variable; thus, tissue data from biosentinel taxa can be useful to assess risk. Dragonfly larvae have emerged as biological indicators of mercury impairment, yet their mercury biodynamics over time and across exposure levels are not well understood. Evaluating these attributes using controlled experimental approaches is an important step to validate larval dragonflies as biosentinels for spatial and temporal trends in mercury risk. We conducted an experimental series quantifying methylmercury trophic transfer from dosed prey to predatory dragonfly larvae at environmentally relevant concentrations. Dragonfly total mercury concentrations increased proportionally by factors of 2.7 to 4.2 with each doubling of prey methylmercury concentration, responding to dietary treatments in 7-28 days and reaching equilibrium in as little as 40 days, supporting their utility to indicate changing mercury exposure regimes. Dosed dragonflies biomagnified methylmercury by factors of 1.0 ± 0.1 to 3.4 ± 0.2 relative to their prey, and biomagnification efficiency decreased by over 40% for each doubling of prey methylmercury concentration. Dragonfly development had dose-dependent effects on bioaccumulation: mercury concentrations increased with growth and decreased with age in higher exposure treatments, whereas they decreased with growth and increased with age in lower exposure treatments. Bioaccumulation also varied taxonomically; within treatments, mean mercury concentrations for each genus varied up to 10% from family-level means. Dragonfly sex, size, and body condition did not significantly affect mercury concentrations. These results help validate and expand the utility of dragonfly larvae as biosentinels to monitor mercury risk and better protect wildlife and human health.
淡水系统中汞的生物可利用性和生物放大作用具有高度变异性；因此，来自生物指示物种的组织数据有助于评估风险。蜻蜓幼虫已成为汞损害的生物指标，但其汞生物动力学随时间和暴露水平的变化情况尚不清楚。使用受控实验方法评估这些特性是验证幼虫蜻蜓作为汞风险时空趋势生物指示物的重要一步。我们进行了一系列实验，在环境相关浓度下，量化甲基汞从投喂猎物到捕食性蜻蜓幼虫的营养转移。随着猎物甲基汞浓度每增加一倍，蜻蜓总汞浓度按比例增加2.7至4.2倍，在7 - 28天内对饮食处理做出反应，并在短短40天内达到平衡，这支持了它们用于指示汞暴露状况变化的效用。相对于猎物，投喂过的蜻蜓将甲基汞生物放大了1.0±0.1至3.4±0.2倍，并且随着猎物甲基汞浓度每增加一倍，生物放大效率降低超过40%。蜻蜓的发育对生物累积有剂量依赖性影响：在高暴露处理中，汞浓度随生长增加而随年龄降低，而在低暴露处理中，汞浓度随生长降低而随年龄增加。生物累积在分类学上也存在差异；在各处理中，每个属的平均汞浓度与科级平均浓度相比最多相差10%。蜻蜓的性别、大小和身体状况对汞浓度没有显著影响。这些结果有助于验证并扩大蜻蜓幼虫作为生物指示物监测汞风险的效用，从而更好地保护野生动物和人类健康。
