Does the severity of non‐flow periods influence ecosystem structure and function of temporary streams? A mesocosm study
Does the severity of non‐flow periods influence ecosystem structure and function of temporary streams? A mesocosm study
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DOI：
10.1111/fwb.13098
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发表时间：
2018-07
影响因子：
2.7
通讯作者：
I. Muñoz;Meritxell Abril;J. P. Casas‐Ruiz;M. Casellas;L. Gómez‐Gener;R. Marcé;M. Menéndez;B. Obrador;S. Sabater;D. Schiller;V. Acuña
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作者：
I. Muñoz;Meritxell Abril;J. P. Casas‐Ruiz;M. Casellas;L. Gómez‐Gener;R. Marcé;M. Menéndez;B. Obrador;S. Sabater;D. Schiller;V. Acuña
全球变化正在极大地改变世界范围内的流动状况。其中最重要的后果是许多永久水道过渡到临时水道，临时河流非流动期的持续时间和频率增加，以及非流动期的严重程度（即辐照度，温度和湿度）增加。目前，人们对非流动期的持续时间、频率和严重程度的变化如何反映临时河流的生物多样性和生物地球化学变化缺乏了解。我们设计了一个使用人工溪流的操纵实验，以评估非流动期对溪流生物膜的严重程度的影响。16条人工溪流被分配到四个处理：连续流，连续不连续性和不连续性与降雨事件。影响进行了评估流生物膜结构（即细菌密度和基础荧光）和功能（光合效率和酶活性），以及二氧化碳排放量和溶解有机物的数量和质量的水柱和沉积物的选定功能。在非流动期间发生的降雨事件增强了有机碳的处理和向大气中的二氧化碳排放，减少了可输出有机碳的沉积物水库，从而减少了流动恢复时河床的溶解有机碳输出。鉴于半干旱和干旱地区降雨频率持续下降的趋势，我们预计临时河流的处理和排放量将减少，并向下游系统输出更多的碳。
Global change is dramatically altering flow regimes worldwide. Among the most important consequences are the transition of many permanent waterways to temporary waterways, the increase in duration and frequency of non‐flow periods of temporary streams, and the increase in the severity (i.e. irradiance, temperature and humidity) of the non‐flow period. Nowadays, there is a lack of knowledge on how changes in duration, frequency and severity of the non‐flow period will reflect on biodiversity and biogeochemical changes in temporary streams. We designed a manipulative experiment using artificial streams to evaluate the effects of severity of the non‐flow period on stream biofilms. Sixteen artificial streams were assigned to four treatments: continuous flow, continuous intermittency and intermittency with and without rain events. Effects were assessed on selected features of stream biofilm structure (i.e. bacterial density and basal fluorescence) and function (photosynthetic efficiency and enzymatic activities), as well as CO₂ emissions and dissolved organic matter quantity and quality from water column and sediments. The occurrence of rain events during the non‐flow period enhanced organic carbon processing and CO₂ emissions to the atmosphere, reducing the sediment reservoir of exportable organic carbon and therefore reducing the dissolved organic carbon exports from streambeds at flow resumption. Given the ongoing reducing trends in the frequency of rain events in semi‐arid and arid regions, we expect temporary streams to process and emit less and to export more carbon to downstream systems.