Supplemental results for "Effects of drying and orientation to perennial refuges on aquatic biodiversity across two basins differing in aridity"

Intermittent streams are globally distributed, comprise over half the length of the global river network, and are expected to become more prevalent. However, most studies of intermittent streams are conducted at extremes of scale, are limited in taxonomic and temporal scope, and focus exclusively on drying patterns. Here, we assessed how both flow intermittency and orientation to perennial refuges affect aquatic invertebrates and aquatic and semi-aquatic vertebrates across two years within two intermittent river basins differing in their aridity. We used loggers to characterize flow intermittency and wet-dry mapping to determine orientation to perennial refuge of reaches. In winter and summer 2015 and 2016, we collected and identified invertebrates and visually surveyed vertebrates. Using permutational multivariate analyses of variance with distance matrices, we found distinct invertebrate communities by basin, flow class (perennial or intermittent), and season, and distinct vertebrate communities by basin, and between flow classes and seasons in the more arid basin. Invertebrate communities had higher beta diversity in the more arid than mesic basin, whereas the opposite was true for vertebrates. We identified indicator species for all combinations of basin and flow class, perennial reaches combined from both basins, each basin, and some combinations of flow class and season within basins. Flow intermittency and orientation to perennial refuge predictors correlated well with both invertebrate and vertebrate communities. However, we did not find nestedness of communities that differed significantly from that expected by chance in response to increasing flow intermittency or distance to refuge. Lastly, basin, flow intermittency, and orientation to perennial refuge predictors were generally important for modeling taxon richness and densities, and richness and densities decreased with increasing flow intermittency and distance to perennial refuge. Collectively, our data suggest that intermittent streams harbor unique biodiversity, but also that some taxa have context-dependent responses to intermittency and orientation to perennial refuges. These findings also suggest that future increases in stream drying are likely to lead to changes to stream communities with high potential for the loss of aquatic biodiversity.For inquiries regarding the contents of this dataset, please contact the Corresponding Author listed in the README.txt file. Administrative inquiries (e.g., removal requests, trouble downloading, etc.) can be directed to [e-mail] item is part of Data, R Code, and Supplemental Results for "Effects of drying and orientation to perennial refuges on aquatic biodiversity across two basins in California, USA". See References, below, for the other parts.

间歇性河流在全球范围内分布广泛，占据了全球河流网络长度的一半以上，且预计其分布将更加普遍。然而，针对间歇性河流的研究大多集中在极端的尺度上，其分类学和时间范围受到限制，且主要关注干旱模式。本研究评估了在两个不同干旱程度的间歇性河流流域中，连续两年内河流流量间歇性和对永久性庇护所的取向如何影响水生无脊椎动物以及水生和半水生脊椎动物。我们利用记录器来表征流量间歇性，并通过干湿映射法确定对永久性庇护所的取向。在2015年和2016年的冬季和夏季，我们收集并鉴定了无脊椎动物，并对脊椎动物进行了视觉调查。通过距离矩阵的置换多元方差分析，我们发现不同流域、流量类别（永久性或间歇性）和季节之间存在显著差异的无脊椎动物群落，而在更加干旱的流域中，根据流域、流量类别以及季节之间的差异，脊椎动物群落也表现出显著的差异。与中生流域相比，干旱流域的无脊椎动物群落具有较高的β多样性，而脊椎动物群落则相反。我们确定了所有流域与流量类别的指示物种，包括来自两个流域的永久性河段、每个流域以及流域内某些流量类别与季节的组合。流量间歇性和对永久性庇护所的取向预测因子与无脊椎动物和脊椎动物群落的相关性良好。然而，我们没有发现随着流量间歇性的增加或到庇护所的距离增加，群落嵌套结构显著偏离随机预期的现象。最后，流域、流量间歇性和对永久性庇护所的取向预测因子通常对建模物种丰富度和密度至关重要，且丰富度和密度随着流量间歇性的增加和对永久性庇护所距离的增加而降低。总体而言，我们的数据表明间歇性河流孕育着独特的生物多样性，但也暗示某些物种对间歇性和对永久性庇护所的取向的反应具有情境依赖性。这些发现还表明，未来河流干涸的增加很可能会导致河流群落的变化，这将对水生生物多样性的丧失产生高风险。有关本数据集内容的相关咨询，请联系README.txt文件中列出的通讯作者。行政询问（例如，移除请求、下载问题等）可发送至[e-mail]。本项为“加利福尼亚州两个流域水生生物多样性受干燥和永久性庇护所取向影响的研究”的数据、R代码和补充结果的一部分。有关其他部分的详细信息，请参阅下文参考文献。