2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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5/21/2019 | 11:30 AM - 11:45 AM | INFLUENCE OF STREAM METABOLISM AND FLOW VARIABILITY ON FISH TROPHIC NICHE IN DESERT STREAMS | 251 DE

INFLUENCE OF STREAM METABOLISM AND FLOW VARIABILITY ON FISH TROPHIC NICHE IN DESERT STREAMS

Flood and drought events have well documented effects on population dynamics, community composition, and many ecosystem processes. What remains less clear are the mechanisms relating streamflow to temporal variations in resource availability and the trophic dynamics of consumers. For example, floods may remove primary producers from the streambed, forcing consumers to subsist on allochthonous food sources. Alternatively, instream GPP may increase rapidly following a flood while stores of benthic detritus recover slowly, increasing consumer reliance on aquatic primary production. We collected seasonal measurements of stream metabolism and fish communities at sites along a gradient of streamflow variability in Arizona. Temporal changes in fish trophic niche were evaluated using stable isotope analysis. Across sites and seasons, food chain length decreased with increasing magnitude of antecedent high and low flow events (flow anomalies). Supporting the hypothesis that disturbances shorten food chains, the trophic position of an omnivorous fish (Agosia chrysogaster) distributed across several sites also decreased with greater flow anomaly magnitude. Quantifying these relationships will help elucidate the contributions of flow and metabolic regimes to spatial and temporal variation in stream food web structure.

Fish
Metabolism
Isotope

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Presenters/Authors

Ethan Baruch (), Arizona State University, ebaruch@asu.edu;