2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/25/2021 | 2:00 PM - 3:30 PM | Warm “winter” temperatures promote reservoir cyanobacterial dominance across enriched nutrient regimes | Virtual Platform
Warm “winter” temperatures promote reservoir cyanobacterial dominance across enriched nutrient regimes
Shifting nutrient regimes characterize many potable source-water reservoirs worldwide, concomitant with global warming. In a southeastern U.S. reservoir, we experimentally assessed short-term in situ phytoplankton assemblage response to three inorganic nitrogen-to-phosphorus (Ni/Pi) ratios in an average cold winter versus a warm winter (mean water temperatures 7C and 10C, respectively). Ratios were imposed with Ni as ammonium or nitrate +/- Pi (phosphate): 32N:1P (ambient P); elevated, 50N:1P (ambient P); and enriched Redfield, 16N:1P (both nutrients added). In the average cold winter, diatoms comprised up to 70% of the total phytoplankton cells, followed by chlorophytes. Diatoms remained dominant, increasing under nitrate enrichment +/-Pi, in the elevated and enriched Redfield treatments. In the warm winter, diatoms and chlorophytes initially dominated the assemblages (up to 40% and 20%, respectively). Cyanobacteria more than doubled in controls and all treatments as diatoms were reduced under ammonium enrichment. While cyanobacteria were stimulated in all ratios, the greatest stimulation was in the enriched Redfield treatment under ammonium+Pi. The findings suggest that the combination of warming winters and increasing ammonium+Pi enrichment will promote the loss of freshwater winter/early spring diatom blooms in favor of cyanobacteria as cultural eutrophication progresses.
- Nutrients
- Climate change
- Monitoring
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Presenters/Authors
Nicole Lindor
(), North Carolina State University, nllindor@ncsu.edu;
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JoAnn Burkholder
(), North Carolina State University, jburk@ncsu.edu;
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