Odum School of Ecology, University of Georgia, Athens, GA, USA; Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA.
Department of Environmental Science, Baylor University, Waco, TX, USA.
Sci Total Environ. 2022 Oct 1;841:156699. doi: 10.1016/j.scitotenv.2022.156699. Epub 2022 Jun 14.
Urban-living wildlife can be exposed to metal contaminants dispersed into the environment through industrial, residential, and agricultural applications. Metal exposure carries lethal and sublethal consequences for animals; in particular, heavy metals (e.g. arsenic, lead, mercury) can damage organs and act as carcinogens. Many bat species reside and forage in human-modified habitats and could be exposed to contaminants in air, water, and food. We quantified metal concentrations in fur samples from three flying fox species (Pteropus fruit bats) captured at eight sites in eastern Australia. For subsets of bats, we assessed ectoparasite burden, haemoparasite infection, and viral infection, and performed white blood cell differential counts. We examined relationships among metal concentrations, environmental predictors (season, land use surrounding capture site), and individual predictors (species, sex, age, body condition, parasitism, neutrophil:lymphocyte ratio). As expected, bats captured at sites with greater human impact had higher metal loads. At one site with seasonal sampling, bats had higher metal concentrations in winter than in summer, possibly owing to changes in food availability and foraging. Relationships between ectoparasites and metal concentrations were mixed, suggesting multiple causal mechanisms. There was no association between overall metal load and neutrophil:lymphocyte ratio, but mercury concentrations were positively correlated with this ratio, which is associated with stress in other vertebrate taxa. Comparison of our findings to those of previous flying fox studies revealed potentially harmful levels of several metals; in particular, endangered spectacled flying foxes (P. conspicillatus) exhibited high concentrations of cadmium and lead. Because some bats harbor pathogens transmissible to humans and animals, future research should explore interactions between metal exposure, immunity, and infection to assess consequences for bat and human health.
城市野生动物可能会接触到通过工业、住宅和农业应用而分散到环境中的金属污染物。金属暴露对动物有致命和亚致死的影响；特别是重金属（如砷、铅、汞）会损害器官并充当致癌物质。许多蝙蝠物种栖息和觅食于人类改造的栖息地，可能会接触到空气、水和食物中的污染物。我们量化了在澳大利亚东部八个地点捕获的三种飞狐物种（果蝠）的皮毛样本中的金属浓度。对于蝙蝠的子样本，我们评估了外寄生虫负担、血液寄生虫感染和病毒感染，并进行了白细胞分类计数。我们研究了金属浓度与环境预测因子（捕获地点周围的季节、土地利用）和个体预测因子（物种、性别、年龄、身体状况、寄生虫、中性粒细胞：淋巴细胞比值）之间的关系。正如预期的那样，在人类影响较大的地点捕获的蝙蝠具有更高的金属负荷。在一个具有季节性采样的地点，蝙蝠在冬季的金属浓度高于夏季，这可能是由于食物供应和觅食方式的变化所致。外寄生虫和金属浓度之间的关系是混合的，表明存在多种因果机制。总的金属负荷与中性粒细胞：淋巴细胞比值之间没有关联，但汞浓度与该比值呈正相关，这与其他脊椎动物类群的应激有关。将我们的研究结果与之前的飞狐研究结果进行比较，发现了几种金属的潜在有害水平；特别是濒危眼镜狐蝠（P. conspicillatus）表现出高浓度的镉和铅。由于一些蝙蝠携带可传播给人类和动物的病原体，未来的研究应探索金属暴露、免疫和感染之间的相互作用，以评估对蝙蝠和人类健康的影响。
