Zhu Dongdong, Lin Xianbiao, Liu Su Mei
Frontiers Science Center for Deep Ocean Multi-spheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
Frontiers Science Center for Deep Ocean Multi-spheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
Mar Pollut Bull. 2025 Nov;220:118463. doi: 10.1016/j.marpolbul.2025.118463. Epub 2025 Jul 23.
Mangroves play an important role in regulating the biogeochemical cycle of nitrogen (N) in coastal wetlands. However, their effects on the N cycle, especially the potential ammonia oxidation rates (PARs) contributed by ammonia-oxidizing archaea (AOA) and bacteria (AOB) in different sedimentary textures remain unclear. Here, we analyzed the PARs, AOA and AOB amoA gene abundances, and stable carbon isotope ratios (δC) of mangrove wetland sediments collected in summer and winter from the muddy and sandy coasts in southern China. The results showed higher sediment PARs and amoA gene copies during summer, and greater values were found on mangrove-vegetated sediments than unvegetated bare flats. PARs and the amoA gene copies were negatively correlated to salinity and pH, which agrees with previous research. However, sediment texture (i.e. organic matter content and grain size) also plays a role, of which muddy sediments were characterized by higher PARs and amoA gene abundances than sandy sediments. Vegetated sediments have a lower pH, smaller grain size, and a higher organic matter and nutrient content. This suggests that mangroves may enhance ammonia oxidation and microbial abundance by altering sediment textures. A greater effect of mangroves on nutrient cycling of sandy coasts implies that mangroves are instrumental in promoting the nutrient levels of sandy coasts. Furthermore, AOA represented <10 % of the amoA gene copies but contributed ca. 40 % of PARs, indicating AOA's central role in ammonia oxidation. Our study showed that mangrove forests are important for microbial abundance and N cycling in different coastal sediment textures.
红树林在调节沿海湿地氮（N）的生物地球化学循环中发挥着重要作用。然而，它们对氮循环的影响，特别是不同沉积质地中氨氧化古菌（AOA）和细菌（AOB）贡献的潜在氨氧化速率（PARs）仍不清楚。在此，我们分析了中国南方夏季和冬季从泥泞和沙质海岸采集的红树林湿地沉积物的PARs、AOA和AOB氨单加氧酶基因丰度以及稳定碳同位素比率（δC）。结果表明，夏季沉积物的PARs和氨单加氧酶基因拷贝数较高，且红树林植被覆盖的沉积物中的数值高于无植被的裸滩。PARs和氨单加氧酶基因拷贝数与盐度和pH呈负相关，这与先前的研究一致。然而，沉积质地（即有机质含量和粒度）也起作用，其中泥泞沉积物的特点是PARs和氨单加氧酶基因丰度高于沙质沉积物。植被覆盖的沉积物pH较低、粒度较小、有机质和养分含量较高。这表明红树林可能通过改变沉积质地来增强氨氧化和微生物丰度。红树林对沙质海岸养分循环的影响更大，这意味着红树林有助于提高沙质海岸的养分水平。此外，AOA占氨单加氧酶基因拷贝数的比例不到10%，但贡献了约40%的PARs，表明AOA在氨氧化中起核心作用。我们的研究表明，红树林对于不同沿海沉积质地中的微生物丰度和氮循环很重要。
