Ecology and the Environment Research Centre, Department of Natural Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, UK.
Ecology and the Environment Research Centre, Department of Natural Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, UK..
Sci Total Environ. 2023 Oct 20;896:165040. doi: 10.1016/j.scitotenv.2023.165040. Epub 2023 Jun 27.
Storm surges, flooding, and the encroachment of seawater onto agricultural land are predicted to increase with climate change. These flooding events fundamentally alter many soil properties and have knock-on effects on the microbial community composition and its functioning. The hypotheses tested in this study were (1) that the extent of change (resistance) of microbial community functioning and structure during seawater flooding is a factor of pre-adaptation to the stress, and (2) if structure and function are altered, the pre-adaptation will result in communities returning to previous state prior to flooding (resilience) faster than unexposed communities. We chose a naturally occurring saltmarsh-terrestrial pasture gradient from which three elevations were selected to create mesocosms. By selecting these sites, we were able to incorporate the legacy of differing levels of seawater ingress and exposure. Mesocosms were submerged in seawater for 0, 1, 96- and 192-h, with half of the mesocosms sacrificed immediately after flooding, and the other half taken after a 14 day "recovery" period. The following parameters were monitored: 1) changes in soil environmental parameters, 2) prokaryotic community composition, and 3) microbial functioning. Our results indicated that any length of seawater inundation significantly altered the physicochemical properties of all the soils, although a greater change is observed in the pasture site compared to the saltmarsh sites. These changes remained following a recovery period. Interestingly, our results indicated that for community composition, there was a high degree of resistance for the Saltmarsh mesocosms, with the Pasture mesocosm displaying higher resilience. Further, we observed a functional shift in the enzyme activities with labile hemicellulose being preferentially utilised over cellulose, with the effect increasing with longer floods. These results suggest that changing bacterial physiology is more critical to understanding the impact of storm surges on agricultural systems than bulk community change.
预计随着气候变化，风暴潮、洪水和海水侵蚀农业用地的情况将会增加。这些洪水事件从根本上改变了许多土壤特性，并对微生物群落组成及其功能产生连锁反应。本研究检验的假设是：(1) 在海水泛滥期间，微生物群落功能和结构变化的程度（抵抗力）是对压力预先适应的一个因素；(2) 如果结构和功能发生变化，预先适应将导致群落比未暴露的群落更快地恢复到洪水前的状态（恢复力）。我们选择了一个自然发生的盐沼-陆地牧场梯度，从中选择了三个海拔高度来创建中观模型。通过选择这些地点，我们能够纳入不同程度海水入侵和暴露的历史。中观模型被淹没在海水中 0、1、96 和 192 小时，其中一半的中观模型在洪水后立即牺牲，另一半在 14 天“恢复”期后牺牲。监测了以下参数：1）土壤环境参数的变化，2）原核生物群落组成，和 3）微生物功能。我们的结果表明，任何长度的海水淹没都会显著改变所有土壤的物理化学性质，尽管在牧场地点观察到的变化大于盐沼地点。这些变化在恢复期后仍然存在。有趣的是，我们的结果表明，对于群落组成，盐沼中观模型具有很高的抵抗力，而牧场中观模型显示出更高的恢复力。此外，我们观察到酶活性的功能转移，其中易降解的半纤维素优先于纤维素被利用，随着洪水时间的延长，这种效应增加。这些结果表明，改变细菌生理学对于理解风暴潮对农业系统的影响比群落整体变化更为关键。
