Mangrove ecosystems are important for carbon storage due to their high productivity and low decomposition rates. Waterways have experienced increased nutrient loads as a result of anthropogenic activities and it is unclear how this may affect carbon and nutrient cycles in downstream mangroves that receive these nutrient-rich waters. Using a laboratory-based incubation experiment, this study aimed to assess the effects of nutrient addition on the diversity and structure of mangrove soil bacterial communities, as well as biomass and activity of the soil microbial community, under different oxygen conditions. Bacterial community diversity and composition was characterised using 16S rRNA gene sequencing and microbial activity was examined through the measurement of microbial respiration and the activities of enzymes associated with organic matter decomposition. Nitrogen addition caused clear shifts in bacterial community composition, with decreases in bacterial diversity and the abundance of sulfate-reducing bacteria. Microbial biomass also decreased with nitrogen addition under reduced oxygen incubations. Changes in bacterial community structure were accompanied by changes in the activity of some enzymes involved in carbon, nitrogen, and phosphorus cycling. Under reduced oxygen conditions, nitrogen addition resulted in a significant increase in the microbial metabolic quotient but no accompanying change in microbial respiration, which was explained by a decrease in microbial biomass. The findings of this study indicate that nitrogen loading has potential implications for microbial communities and carbon and nutrient cycling in mangrove environments that warrant further investigation under field conditions.

红树林生态系统因其高生产率和低分解率而对于碳存储很重要。由于人为活动，水道的养分负荷增加，目前尚不清楚这如何影响接受这些养分丰富的水域的下游红树林的碳和养分循环。本研究以实验室为基础的孵化实验，旨在评估养分添加对不同氧气条件下红树林土壤细菌群落多样性和结构以及土壤微生物群落生物量和活性的影响。使用16S rRNA基因测序来表征细菌群落的多样性和组成，并通过测量微生物呼吸作用以及与有机物分解相关的酶的活性来检查微生物活性。氮的添加引起细菌群落组成的明显变化，细菌多样性降低，硫酸盐还原菌数量丰富。在减少氧气孵育的情况下，氮的添加也会使微生物生物量减少。细菌群落结构的变化伴随着参与碳，氮和磷循环的某些酶活性的变化。在氧气减少的条件下，氮的添加导致微生物代谢商的显着增加，但微生物呼吸没有伴随的变化，这可以通过减少微生物量来解释。这项研究的结果表明，氮含量对红树林环境中的微生物群落以及碳和养分循环具有潜在的影响，因此有必要在田间条件下进行进一步研究。