2022 Early Hearing Detection & Intervention Virtual Conference
March 13 - 15, 2022
5/25/2021 | 2:00 PM - 3:30 PM | USING PULSE-AMPLITUDE-MODULATED FLUOROMETRY TO ASSESS ALGAL PHOTOSYNTHETIC RESPONSES TO NUTRIENTS IN EUTROPHIC AGRICULTURAL WATERSHEDS | Virtual Platform
USING PULSE-AMPLITUDE-MODULATED FLUOROMETRY TO ASSESS ALGAL PHOTOSYNTHETIC RESPONSES TO NUTRIENTS IN EUTROPHIC AGRICULTURAL WATERSHEDS
Eutrophication continues to impact freshwater ecosystems in agriculturally dominated watersheds throughout the world. Two agriculturally influenced watersheds with varying agricultural best management practices (BMPs), Roundaway Lake (acreage, 1.4% BMPs) and Beasley Lake (acreage, 17.1% BMPs) in western Mississippi, were studied monthly during the growing season to determine algal photosynthetic responses to nutrients. Long-term monitoring (9 years) indicate Roundaway is more eutrophic than Beasley. Pulse-amplitude-modulated (PAM) fluorometry was used to assess nutrient limitation and gradient responses for algal photosynthesis. Algal photosynthetic responses to nutrient gradients were determined using Michaelis-Menten regressions to obtain half-nutrient saturation constants (K). Algal PAM fluorometric responses were associated with algal growth rate (R2, 0.321-0.530). Phytoplankton photosynthesis showed primarily N+P limitation in both lakes with some N-only limitation or no limitation and only rare P limitation. Values for K varied widely: 0.039-1.771 mg TN/L and 0.010-0.423 mg TP/L. However, models indicated K was generally lower in Beasley than Roundaway indicating greater nutrient sensitivity in Beasley. Results indicate BMPs mitigating eutrophication can affect algal photosynthesis and that PAM fluorometry is a sensitive and useful tool for assessing algal photosynthesis nutrient limitation and sensitivity in eutrophic lakes.
- Biological effects
- Monitoring
- Land use
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Presenters/Authors
Richard Lizotte
(), USDA-ARS, Richard.Lizotte@usda.gov;
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Jason Taylor
(), USDA-ARS, Jason.Taylor@usda.gov;
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Martin Locke
(), USDA-ARS, martin.locke@ars.usda.gov ;
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