Drying in alpine streams might decrease aquatic-terrestrial trophic linkages by reducing terrestrial predation on aquatic prey. We tested this hypothesis by investigating whether a common riparian predator (hunting spiders) in alpine environments assimilated a lower proportion of aquatic prey with increasing stream intermittency. We used high temporal-resolution data from electrical resistance sensors to map patterns of naturally-occurring flow intermittency across 30 headwater streams of Val Roseg, a glacierized catchment in the Swiss Alps. We collected riparian hunting spiders, as well as potential terrestrial and aquatic macroinvertebrate prey, from streams and their associated riparian zones across two seasons (Alpine spring and summer). We estimated aquatic contributions to spider diets (p_A) using (i) a gradient approach with aquatic invertebrate and spider carbon stable isotope ratio values (δ¹³C), and (ii) Bayesian carbon and nitrogen (δ¹⁵N) isotope mixing models. Spider p_A from the gradient method were not statistically different from zero in spring (0.08 ± 0.10) and low in summer (0.16 ± 0.04). Mixing models also estimated low dependence on aquatic prey in both seasons, although with potentially higher contributions in summer. Spider diet did not vary with increasing flow intermittency in either season. Our results suggested that alpine hunting spiders obtain most of their carbon from terrestrial prey. The slight increase in spider p_A during summer may correlate with peak emergence periods for aquatic insects, indicating opportunistic feeding by this riparian predator.

高山溪流中的干燥可能会通过减少水生猎物上的陆地捕食来减少水生陆地的营养联系。我们通过调查高山环境中常见的河岸捕食者（狩猎蜘蛛）是否随着水流间歇性的增加而吸收了较低比例的水族猎物，从而检验了这一假设。我们使用了来自电阻传感器的高时间分辨率数据，绘制了瑞士阿尔卑斯山冰川集水区Val Roseg的30条上游水流的自然流动间歇性模式。我们在两个季节（高山春季和夏季）的溪流及其相关的河岸带中收集了河岸狩猎蜘蛛以及潜在的陆地和水生大型无脊椎动物猎物。我们估算了水生食物对蜘蛛饮食的贡献（p _A）使用（i）水生无脊椎动物和蜘蛛碳稳定同位素比的值（梯度方法δ ¹³ C），和（ii）贝叶斯碳和氮（δ ¹⁵ N）同位素混合模型。梯度法得出的蜘蛛p _A在春季和春季没有统计学差异，为零（0.08±0.10），在夏季较低（0.16±0.04）。混合模型还估计两个季节对水生猎物的依赖性都较低，尽管夏季的贡献可能更高。在任何一个季节，蜘蛛的饮食都没有随着流量间歇的增加而变化。我们的结果表明，高山狩猎蜘蛛从陆地猎物获取大部分碳。蜘蛛p _A略有增加 在夏季，这可能与水生昆虫的高峰出现时期有关，表明该河岸捕食者是机会性觅食。