School of Biology and Ecology, Climate Change Institute, University of Maine, Chadbourne Hall, Orono, ME, USA.
Biodiversity Research Institute, 276 Canco Rd., Portland, ME, 04103, USA.
Ecotoxicology. 2020 Oct;29(8):1240-1253. doi: 10.1007/s10646-020-02190-8. Epub 2020 Mar 19.
Many migratory songbirds are at high risk of methylmercury (MeHg) exposure due to their trophic position and foraging in and around wetland habitats. Methylmercury has the potential to alter migratory behaviors and physiology via neurological impairment or reduced flight performance and can be remobilized from songbird muscle tissue during migration, increasing the risk of acute MeHg exposure. To document MeHg exposure and its relationship with physical condition in migratory songbirds, we sampled passerine blood and feathers at a migration stopover site on Key Biscayne, FL during fall and spring from 2009 to 2012. We found evidence that spring blood total mercury (THg) concentrations decreased throughout the day and that fall feather THg concentrations changed over the migratory season. Total mercury exposure was marginally correlated with migratory fat stores and related to changes in pectoral muscle thickness by time of day. These patterns suggest that environmentally relevant levels of THg are related to, and may be influencing, the physical condition of free-living migrating songbirds. Further research and monitoring during the migratory period will be important to elucidate exposure risk across multiple species and assess the potential for effects during this complex period of the annual cycle.
许多候鸟由于其在湿地生境及其周围的取食生态位而处于高甲基汞（MeHg）暴露风险之中。甲基汞有可能通过神经损伤或降低飞行性能来改变候鸟的迁徙行为和生理机能，并且在迁徙过程中可以从候鸟肌肉组织中重新释放出来，从而增加急性 MeHg 暴露的风险。为了记录候鸟的 MeHg 暴露及其与迁徙期间身体状况的关系，我们在 2009 年至 2012 年期间，在佛罗里达州比斯坎湾的一个迁徙中途停留点，在秋季和春季从雀形目鸟类的血液和羽毛中采样。我们发现，春季血液总汞（THg）浓度全天下降，秋季羽毛 THg 浓度在迁徙季节发生变化。总汞暴露与迁徙脂肪储存量呈边缘相关，并且与每日时间的胸肌厚度变化有关。这些模式表明，与环境相关的 THg 水平与自由生活的迁徙候鸟的身体状况有关，并且可能会影响它们的身体状况。在迁徙期间进行进一步的研究和监测对于阐明多种物种的暴露风险以及评估在这一年度周期的复杂期间的潜在影响非常重要。
