University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G2, Canada.
Sci Total Environ. 2023 Aug 10;885:163763. doi: 10.1016/j.scitotenv.2023.163763. Epub 2023 May 3.
Methylmercury (MeHg) is a toxic form of mercury that bioaccumulates in organisms and biomagnifies through food webs. MeHg concentrations can be high in aquatic environments, and this puts high trophic-level predators who derive energy originating from aquatic environments at risk of toxic effects. Due to the potential for bioaccumulation of MeHg over an individual's life, the risk of MeHg toxicity may increase as animals age, and this risk may be especially high in species with relatively high metabolic rates. Total mercury (THg) concentrations were measured from the fur of adult female little brown bats (Myotis lucifugus) collected between 2012 and 2017 in Salmonier Nature Park, Newfoundland and Labrador. Using linear mixed-effects models, the effects of age, year, and day of capture on THg concentrations were evaluated and interpreted with AIC and multi-model inference. We expected that THg concentrations would increase with age, and that due to annual summer moulting, individuals captured earlier in the season would have lower THg concentrations than individuals captured later in the season. Contrary to expectations, THg concentrations decreased with age and date of capture did not explain any variation in concentration. Among individuals, there was a negative relationship between the initial THg concentration of an individual and the rate of change in THg concentrations with age. Using a regression analysis, we found evidence of a population-level decline in THg concentrations in fur over the 6-year study period. Overall, the results indicate that adult female bats eliminate enough MeHg from their tissues to affect a decrease in THg concentrations in their fur over time, and that young adults are potentially at the greatest risk of experiencing toxic effects from high MeHg concentrations; this could result in reduced reproductive output, and warrants further research.
甲基汞（MeHg）是一种有毒的汞形式，在生物体内积累，并通过食物网生物放大。MeHg 浓度在水生环境中可能很高，这使从水生环境中获取能量的高营养级捕食者面临毒性影响的风险。由于 MeHg 在个体一生中可能发生生物积累，因此随着动物年龄的增长，MeHg 毒性的风险可能会增加，而在代谢率相对较高的物种中，这种风险可能特别高。2012 年至 2017 年间，在纽芬兰和拉布拉多的鲑鱼自然公园采集了成年雌性小棕蝠（Myotis lucifugus）的皮毛，测量了总汞（THg）浓度。使用线性混合效应模型，评估了年龄、年份和捕获日期对 THg 浓度的影响，并通过 AIC 和多模型推理进行了解释。我们预计 THg 浓度会随年龄增长而增加，并且由于每年夏季换羽，在季节早期捕获的个体的 THg 浓度会低于在季节后期捕获的个体。与预期相反，THg 浓度随年龄下降，而捕获日期并未解释浓度的任何变化。在个体之间，个体的初始 THg 浓度与随年龄变化的 THg 浓度变化率之间存在负相关关系。通过回归分析，我们发现 6 年研究期间皮毛中 THg 浓度呈现出种群水平下降的证据。总体而言，研究结果表明，成年雌性蝙蝠从组织中清除了足够的 MeHg，导致其皮毛中的 THg 浓度随时间推移而降低，而年轻的成年蝙蝠可能面临着来自高 MeHg 浓度的毒性影响的最大风险；这可能导致繁殖产量减少，值得进一步研究。
