Fujian Provincial Key Laboratory for Subtropical Resources and Environment, Fujian Normal University , Fuzhou, Fujian, China.
Department of Biosciences, Swansea University , Swansea, United Kingdom.
Appl Environ Microbiol. 2023 Sep 28;89(9):e0080723. doi: 10.1128/aem.00807-23. Epub 2023 Sep 6.
Complete ammonia oxidizers (comammox ) are ubiquitous in coastal wetland sediments and play an important role in nitrification. Our study examined the impact of habitat modifications on comammox communities in coastal wetland sediments across tropical and subtropical regions of southeastern China. Samples were collected from 21 coastal wetlands in five provinces where native mudflats were invaded by and subsequently converted to aquaculture ponds. The results showed that comammox abundances were mainly influenced by sediment grain size rather than by habitat modifications. Compared to marshes and native mudflats, aquaculture pond sediments had lower comammox diversity, lower clade A.1 abundance, and higher clade A.2 abundance. Sulfate concentration was the most important factor controlling the diversity of comammox . The response of comammox community to habitat change varied significantly by location, and environmental variables accounted for only 11.2% of the variations in community structure across all sites. In all three habitat types, dispersal limitation largely controlled the comammox community assembly process, indicating the stochastic nature of these sediment communities in coastal wetlands. IMPORTANCE Comammox have recently gained attention for their potential role in nitrification and nitrous oxide (NO) emissions in soil and sediment. However, their distribution and assembly in impacted coastal wetland are poorly understood, particularly on a large spatial scale. Our study provides novel evidence that the effects of habitat modification on comammox communities are dependent on the location of the wetland. We also found that the assembly of comammox communities in coastal wetlands was mainly governed by stochastic processes. Nevertheless, sediment grain size and sulfate concentration were identified as key variables affecting comammox abundance and diversity in coastal sediments. These findings are significant as they advance our understanding of the environmental adaptation of comammox and how future landscape modifications may impact their abundance and diversity in coastal wetlands.
完全氨氧化菌（Comammox）广泛存在于沿海湿地沉积物中，在硝化作用中发挥着重要作用。本研究考察了生境改变对中国东南热带和亚热带地区沿海湿地沉积物中 Comammox 群落的影响。研究从中国五个省份的 21 个沿海湿地采集样本，这些湿地中原有的泥滩被入侵，并随后被改造成水产养殖池塘。研究结果表明，Comammox 的丰度主要受沉积物粒径的影响，而不受生境改变的影响。与 沼泽和原生泥滩相比，水产养殖池塘沉积物中的 Comammox 多样性较低，A.1 类群丰度较低，A.2 类群丰度较高。硫酸盐浓度是控制 Comammox 多样性的最重要因素。Comammox 群落对生境变化的响应因地点而异，环境变量仅解释了所有地点群落结构变化的 11.2%。在所有三种生境类型中，扩散限制在很大程度上控制了 Comammox 群落的组装过程，这表明沿海湿地这些沉积物群落具有随机性。重要性 Comammox 因其在土壤和沉积物中硝化作用和氧化亚氮（NO）排放中的潜在作用而受到关注。然而，它们在受干扰的沿海湿地中的分布和组装情况知之甚少，特别是在大的空间尺度上。本研究提供了新的证据，表明生境改变对 Comammox 群落的影响取决于湿地的位置。我们还发现，沿海湿地 Comammox 群落的组装主要受随机过程的控制。然而，沉积物粒径和硫酸盐浓度被确定为影响沿海沉积物中 Comammox 丰度和多样性的关键变量。这些发现具有重要意义，因为它们增进了我们对 Comammox 环境适应的理解，以及未来景观改变如何影响沿海湿地中 Comammox 的丰度和多样性。
