2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/22/2019 | 9:30 AM - 9:45 AM | SEASONAL AND LONGITUDINAL NUTRIENT LIMITATION PATTERNS IN A WATERSHED INFLUENCE BY IRRIGATION DELIVERY AND RETURN FLOW | 250 DE
SEASONAL AND LONGITUDINAL NUTRIENT LIMITATION PATTERNS IN A WATERSHED INFLUENCE BY IRRIGATION DELIVERY AND RETURN FLOW
Irrigation delivery of snowmelt from mountain reservoirs supports agriculture in the Yakima River Basin of Washington state. Yakima River water quality degrades longitudinally as irrigation return flows load nitrogen and phosphorus into the river. Moreover, stream water N:P ratios are low during irrigation season as low-nutrient snowmelt is delivered, and N:P ratios increase shortly after irrigation season ends as shallow ground water discharges nitrate-rich water back to streams. We hypothesized that longitudinal water quality degradation would relieve nutrient limitation in downstream ecosystems and that the seasonal change in N:P ratios would change nutrient limitation patterns during and after irrigation season. After deploying NDS arrays with N, P, and Si, the most common nutrient limitation response was nitrogen limitation of respiration (8 of 12 assays) and silica limitation of production (5 of 12 assays). We did not see downstream nutrient limitation relief, likely because biofilm nutrient demand never saturated. However, nutrient demand was more likely to differ between summer and fall in the sites most affected by agricultural return flow indicating that water management can change seasonal and longitudinal patterns of biofilm nutrient demand.
- Stoichiometry
- Hydrology
- Nutrients
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Presenters/Authors
Clay Arango
(), Central Washington University, arangoc@cwu.edu;
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Sarah Roley
(), Washington State University Tri Cities, sarah.roley@wsu.edu ;
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Alexander Alexiades
(), Heritage University, alexiades_a@heritage.edu;
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