1. Mountain streams in southwestern European Alps are currently shifting from perennial to intermittent flow due to the combined effects of climate change and local anthropogenic pressures. Given that flow intermittency is a recently documented phenomenon in the Alps, only scattered studies have investigated functional and taxonomical diversity of benthic invertebrate communities in recently intermittent Alpine streams.
2. We used a hierarchical sampling design to investigate patterns in taxonomic and functional diversity of benthic invertebrate communities in 13 recently intermittent Alpine streams in north‐west Italy. in April 2017, we sampled benthic communities in two reaches of each stream with different hydrological conditions: a control reach, with permanent flow; and an intermittent reach, which recently experienced non‐flow periods in summer.
3. We tested for the response of taxonomic richness at multiple spatial scales by partitioning total diversity into the average richness of local communities and the richness due to variation among local communities both within and among reaches. By partitioning total diversity (γ) into its local (α) and turnover (β) components we showed a decrease in local and regional species richness both within and among reaches, whereas variation among communities was significantly lower in intermittent reaches at the reach scale only.
4. The analysis of multidimensional trait space of macroinvertebrate communities in reaches with different hydrological conditions revealed a significant reduction of functional diversity, dispersion, and evenness in intermittent reaches. There was trait overdispersion in intermittent reaches, as these hosted both typical Alpine taxa and organisms adapted to flow intermittency. In particular, we observed the replacement of taxa with aquatic respiration and those preferring medium‐ to fast‐flowing oligotrophic waters by taxa adapted to lentic habitats, air breathing and with larval dormancy phases.
5. These results indicate that recent flow intermittency has caused drastic changes in benthic invertebrate communities in Alpine streams. Our work highlights the importance of integrating taxonomic and functional diversity to thoroughly assess the impacts of flow intermittency.

中文翻译：

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最近断断续续的高山水道中大型无脊椎动物群落的分类和功能均质化

1. 由于气候变化和当地人为压力的共同作用，欧洲西南部阿尔卑斯山的山溪目前正从常年性水流转移到间歇性水流。鉴于流动间歇性是阿尔卑斯山最近记录的现象，只有分散的研究调查了最近断断续续的高山溪流中底栖无脊椎动物群落的功能和分类学多样性。
2. 我们使用分层抽样设计来调查意大利西北部13条最近断断续续的高山河流底栖无脊椎动物群落的分类学和功能多样性模式。在2017年4月，我们在每条河流的两个河段采样了不同水文条件的底栖生物：间歇性到达，最近在夏季经历了非流量期。
3. 我们通过将总多样性分为本地社区的平均富裕度和因河内及河段之间本地社区之间的变异而造成的富裕度，在多个空间尺度上测试了分类学富裕度的响应。通过将总多样性（γ）分为其局部（α）和周转（β）分量，我们显示了河段内和河段之间局部和区域物种丰富度的下降，而仅在河段范围内，间歇性河段的群落间变异明显较低。
4. 对不同水文条件下河段大型无脊椎动物群落的多维特征空间进行分析，发现断续河段的功能多样性，分散性和均匀性显着降低。在间歇性河段中存在过度分散的特征，因为这些河段既有典型的高山分类群，也有适应流动间歇性的生物。特别是，我们观察到水生呼吸替代了分类单元，而偏爱中型至快速流动的贫营养水的人群则被适应于透镜状生境，空气呼吸和幼虫休眠期的分类单元所替代。
5. 这些结果表明，最近的水流间歇性已经引起了高山河流底栖无脊椎动物群落的剧烈变化。我们的工作突显了整合分类学和功能多样性以彻底评估流程间歇性影响的重要性。