Coastal marsh lagoons are of high ecological relevance playing a key role in the carbon cycle but are threatened to disappear due to global change effects. Restoration practices can counteract this process. This study compares the microbial heterotrophic functioning in three “new” man-made lagoons (created in 2016) to that in three “old” lagoons (two natural plus one created in 2002) from a Mediterranean coastal marsh. The activity of a range of microbial extracellular enzymes, the functional diversity, and the dissolved organic matter (DOM) quality, together with microbial biomass and water physic-chemistry were analysed seasonally in the water column of the six lagoons during 2017. Seasonality was a key driver for the lagoons microbial functioning mainly characterized by lowest microbial activities in winter when DOM was highly aromatic after storm events and an increase in organic matter degradation capabilities from winter to summer probably due to a rise in temperature and DOM input from primary production. Significant differences among lagoons appeared when they were less connected (summer and autumn), and old lagoons showed a greater utilization of proteinaceous and polysaccharidic compounds than new lagoons probably linked to their greater algal biomass (chlorophyll content), which may be supported by their larger phosphorus content. In autumn, there was also a greater use of allochthonous plant material in the old lagoons (higher XYL, and XYL/GLU ratio) probably related to their greater development of riparian vegetation. The functional diversity was the lowest in autumn when the lagoons showed distinct functional fingerprints and the lagoon created in 2002 was grouped with the new ones and distinguished from the natural ones, suggesting that it did not achieve complete restoration. Results indicate that microbial functional parameters related to organic matter use are a relevant and sensitive tool to study lagoon restoration processes, reflecting whole ecosystem nutrient and carbon cycling.

沿海沼泽泻湖具有高度的生态相关性，在碳循环中发挥着关键作用，但由于全球变化的影响而面临消失的威胁。恢复实践可以抵消这一过程。这项研究比较了地中海沿海沼泽中三个“新”人造泻湖（2016 年创建）与三个“旧”泻湖（两个天然泻湖加一个 2002 年创建）的微生物异养功能。2017 年对六个泻湖水体中一系列微生物胞外酶的活性、功能多样性和溶解有机质 (DOM) 质量，以及微生物生物量和水物理化学进行了季节性分析。季节性是泻湖微生物功能的关键驱动因素，主要特征是冬季微生物活动最低，当暴风雨事件后 DOM 高度芳香化，以及从冬季到夏季有机物降解能力的增加，可能是由于温度升高和来自初级的 DOM 输入。生产。当泻湖连接较少时（夏季和秋季），泻湖之间出现显着差异，旧泻湖比新泻湖显示出更多的蛋白质和多糖化合物利用，这可能与其更大的藻类生物量（叶绿素含量）有关，这可能是由于它们更大的藻类生物量（叶绿素含量）磷含量。在秋季，旧泻湖（较高的 XYL，和 XYL/GLU 比率）可能与其河岸植被的更大发展有关。秋季功能多样性最低，泻湖显示出明显的功能指纹，2002年创建的泻湖与新泻湖归为一组，与自然泻湖区分开来，表明它没有实现完全恢复。结果表明，与有机物质利用相关的微生物功能参数是研究泻湖恢复过程的相关且敏感的工具，反映了整个生态系统的养分和碳循环。