Zhu Wei, Lv Yan, Zhang Qun-De, Chang Li-Ming, Chen Qi-Heng, Wang Bin, Jiang Jian-Ping
CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
College of Life Sciences, Henan Normal University, Xinxiang 453007, China.
Sci Total Environ. 2023 Mar 1;862:160817. doi: 10.1016/j.scitotenv.2022.160817. Epub 2022 Dec 9.
Heavy metal pollution poses a serious threat to ecosystems. Currently, there is a lack of field data that would enable us to gain a systematic understanding of the influences of heavy metals on aquatic ecosystems, especially the interactions between environments and animals. We studied the relationships between the variations in heavy metal concentrations (10 species including Pb in sediments and surface water), the community structure of environmental and symbiotic microbiota, and the gut traits of Bufo gargarizans tadpoles across 16 sampling sites on the Chengdu Plain through rigorous statistical analysis and laboratory validation. The results show that heavy metal concentrations, especially the Pb concentration of the sediment, are linked to the variations in sediment and tadpoles' gut microbiomes but not to water microbiota. For the sediment microbiota, Pb causes a trade-off between the proportions of Burkholderiales and Verrucomicrobiae and affects the methane, sulfide, and nitrate metabolisms. For tadpoles, a high sediment Pb content leads to a low abundance of gut aerobic bacteria and a large relative gut weight under both field and laboratory conditions. In addition, Pb promotes the growth of B. gargarizans tadpoles under laboratory conditions. These effects seem to be beneficial to tadpoles. However, a high Pb content leads to a low abundance of probiotic bacteria (e.g., Verrucomicrobiae, Eubacteriaceae, and Cetobacterium) and a high abundance of pathogenic bacteria in the gut and environment, suggesting potential health risks posed by Pb. Interestingly, there is a causal relationship between Pb-induced variations in sediment and symbiotic microbiotas, and the latter is further linked to the variation in relative gut weight of tadpoles. This suggests a cascading effect of Pb on the ecosystem. In conclusion, our results indicate that among the heavy metals, the Pb in sediment is a critical factor affecting the aquatic ecosystem through an environment-gut-physiology pathway mediated by microbiota.
重金属污染对生态系统构成严重威胁。目前，缺乏能让我们系统了解重金属对水生生态系统影响，尤其是环境与动物之间相互作用的实地数据。我们通过严格的统计分析和实验室验证，研究了成都平原16个采样点沉积物和地表水中10种重金属（包括铅）浓度变化、环境和共生微生物群落结构以及中华大蟾蜍蝌蚪肠道特征之间的关系。结果表明，重金属浓度，尤其是沉积物中的铅浓度，与沉积物和蝌蚪肠道微生物群的变化有关，但与水体微生物群无关。对于沉积物微生物群，铅导致伯克霍尔德氏菌目和疣微菌门比例之间的权衡，并影响甲烷、硫化物和硝酸盐代谢。对于蝌蚪，在野外和实验室条件下，沉积物中高铅含量都会导致肠道需氧菌丰度降低和相对肠道重量增大。此外，在实验室条件下，铅促进中华大蟾蜍蝌蚪的生长。这些影响似乎对蝌蚪有益。然而，高铅含量会导致肠道和环境中益生菌（如疣微菌门、真杆菌科和鲸杆菌属）丰度降低，病原菌丰度升高，这表明铅存在潜在健康风险。有趣的是，铅引起的沉积物和共生微生物群变化之间存在因果关系，后者又进一步与蝌蚪相对肠道重量的变化相关。这表明铅对生态系统具有级联效应。总之，我们的结果表明，在重金属中，沉积物中的铅是通过微生物群介导的环境-肠道-生理途径影响水生生态系统的关键因素。
