Riparian hunting spiders do not rely on aquatic subsidies from intermittent alpine streams

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