State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Beijing 10038, China; Department of Water Ecology and Environment, China Institute of Water Resources and Hydropower Research, Beijing 100038, China; Laboratory of Eco-Environmental Engineering Research, State Environmental Protection Key Laboratory of Soil Health and Green Remediation, Huazhong Agricultural University, Wuhan 430070, China.
State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Beijing 10038, China; Department of Water Ecology and Environment, China Institute of Water Resources and Hydropower Research, Beijing 100038, China.
Ecotoxicol Environ Saf. 2023 May;256:114907. doi: 10.1016/j.ecoenv.2023.114907. Epub 2023 Apr 12.
The construction of the reservoir has changed the nitrogen migration and transformation processes in the river, and a large amount of sediment deposition in the reservoir may also lead to the spatial differentiation of complete ammonia oxidation (comammox) bacteria. The study investigated the abundance and diversity of comammox bacteria in the sediments of three cascade reservoirs, namely, Xiaowan, Manwan, and Nuozhadu on the Lancang River in China. In these reservoirs, the average amoA gene abundance of clade A and clade B of comammox bacteria, ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) was 4.16 ± 0.85 × 10, 1.15 ± 0.33 × 10, 7.39 ± 2.31 × 10, and 3.28 ± 0.99 × 10 copies g, respectively. The abundance of clade A was higher than that of other ammonia oxidizing microorganisms. The spatial variation of comammox bacteria abundance differed among different reservoirs, but the spatial variation trends of the two clades of comammox bacteria in the same reservoir were similar. At each sampling point, clade A1, clade A2, and clade B coexisted, and clade A2 was usually the dominant species. The connection between comammox bacteria in the pre-dam sediments was looser than that in non-pre-dam sediments, and comammox bacteria in pre-dam sediments exhibited a simpler network structure. The main factor affecting comammox bacteria abundance was NH-N, while altitude, temperature, and conductivity of overlying water were the main factors affecting comammox bacteria diversity. Environmental changes caused by differences in the spatial distribution of these cascade reservoirs may be the main driver of the changes of community composition and abundance of comammox bacteria. This study confirms that the construction of cascade reservoirs results in niche spatial differentiation of comammox bacteria.
水库的建设改变了河流中氮的迁移转化过程，而水库中大量的泥沙淤积也可能导致完全氨氧化（comammox）细菌的空间分化。本研究调查了中国澜沧江上小湾、漫湾和糯扎渡三级梯级水库沉积物中 comammox 细菌的丰度和多样性。在这些水库中，comammox 细菌的 clade A 和 clade B、氨氧化古菌（AOA）和氨氧化细菌（AOB）的 amoA 基因丰度平均值分别为 4.16±0.85×10^5、1.15±0.33×10^5、7.39±2.31×10^5和 3.28±0.99×10^5copies g^-1。clade A 的丰度高于其他氨氧化微生物。comammox 细菌丰度的空间变化在不同水库之间存在差异，但同一水库中两个 clade 的空间变化趋势相似。在每个采样点，clade A1、clade A2 和 clade B 共存，且 clade A2 通常是优势种。大坝前沉积物中 comammox 细菌之间的联系比非大坝前沉积物中更为松散，大坝前沉积物中 comammox 细菌的网络结构更为简单。影响 comammox 细菌丰度的主要因素是 NH-N，而海拔、上覆水温度和电导率是影响 comammox 细菌多样性的主要因素。这些梯级水库空间分布差异引起的环境变化可能是 comammox 细菌群落组成和丰度变化的主要驱动因素。本研究证实，梯级水库的建设导致了 comammox 细菌的生态位空间分化。
