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Abstract
Intermittent streams are predicted to become more prevalent globally as we face challenges associated with climate change and water scarcity. Understanding how intermittency influences the trophic dynamics of secondary consumer fishes is critical for informing ecosystem function pathways in streams with high fish diversity. This study compared the diets of leuciscid and percid fishes in perennial and intermittent streams to determine the immediate and cumulative effects of hydrology on food webs. Fishes in perennial streams had more diverse diets compared to fishes in intermittent streams for both summer and fall seasons. Mean δ15N and δ13C isotope signatures of fishes in intermittent streams were significantly lower in the fall compared to summer. In contrast, seasonal shifts in isotope signatures were not observed in perennial streams. Consumption of benthic crustaceans, including copepods, Daphnia, and isopods was significantly greater in intermittent streams in the fall compared to pre-flow cessation conditions in the summer.