Several Alpine streams are currently facing recurrent summer drying events with detrimental consequences on stream detritivores, i.e., shredders, due to negative effects via changes the organic matter (CPOM) availability. We examined the ecological requirements of three phylogenetically related shredder genera belonging to the family of Nemouridae (Plecoptera), namely Nemoura, Protonemura and Amphinemura, in 14 Alpine streams recently facing recurrent summer flow intermittency events. We evaluated the overlap among their ecological niches measured in terms of hydraulic stress, substrate composition, changes in CPOM availability and competition with other shredder taxa (i.e., presence of individuals of other shredders) and we examined potential changes in their ecological niches between permanent and intermittent sites. The ecological niches of Protonemura and Amphinemura overlap broadly, but not with Nemoura, suggesting only partial potential competition. The reduced CPOM availability decreased the individual abundance of the three genera in intermittent sites, where they consistently preferred microhabitats with high CPOM availability and low competition with other shredder taxa, possibly due to food limitation. Overall, our results emphasize how the negative effect of flow intermittency on shredders in Alpine streams is mainly due to the decrease in CPOM availability, with consequent potential bottom up effects on stream ecosystem functionality.

中文翻译：

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流动间歇性通过降低意大利西南阿尔卑斯山最近间歇性高山溪流中 CPOM 的可用性，对三种系统发育相关的碎石蝇产生负面影响

由于有机物质 (CPOM) 可用性变化带来的负面影响，几条高山河流目前正面临反复发生的夏季干旱事件，对河流碎屑动物（即粉碎机）产生不利影响。我们检查了属于 Nemouridae (Plecoptera) 家族的三个系统发育相关切碎机属的生态要求，即 Nemoura、Protonemura 和 Amphinemura，在最近面临周期性夏季流动间歇性事件的 14 条高山溪流中。我们评估了在水压力、基质组成、CPOM 可用性的变化以及与其他粉碎机分类群的竞争（即其他粉碎机个体的存在）方面测量的生态位之间的重叠，我们检查了永久和间歇性站点。Protonemura 和 Amphinemura 的生态位广泛重叠，但与 Nemoura 没有重叠，这表明只有部分潜在竞争。CPOM 可用性的降低降低了这三个属在间歇性地点的个体丰度，在这些地方，它们始终喜欢具有高 CPOM 可用性和与其他粉碎机分类群低竞争的微生境，这可能是由于食物限制。总体而言，我们的结果强调了流动间歇性对高山河流破碎机的负面影响主要是由于 CPOM 可用性的降低，从而对河流生态系统功能产生潜在的自下而上的影响。他们始终喜欢 CPOM 可用性高且与其他粉碎机分类群竞争低的微生境，这可能是由于食物限制。总体而言，我们的结果强调了流动间歇性对高山河流破碎机的负面影响主要是由于 CPOM 可用性的降低，从而对河流生态系统功能产生潜在的自下而上的影响。他们始终喜欢 CPOM 可用性高且与其他粉碎机分类群竞争低的微生境，这可能是由于食物限制。总体而言，我们的结果强调了流动间歇性对高山河流破碎机的负面影响主要是由于 CPOM 可用性的降低，从而对河流生态系统功能产生潜在的自下而上的影响。