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ARS Home » Southeast Area » Auburn, Alabama » Soil Dynamics Research » Research » Publications at this Location » Publication #412847
Research Project: Sustaining Productivity and Ecosystem Services of Agricultural and Horticultural Systems in the Southeastern United States

Location: Soil Dynamics Research

Title: Evaluating the sensitivity of phytoplankton to copper sulfate pentahydrate at industry standard doses in hypereutrophic communities

Author
item HENNESSEY, A - Auburn University
item MCDONALD, M - Auburn University
item JOHNSON, P - Auburn University
item GLADFELTER, M - Auburn University
item MERRILL, K - Auburn University
item TENISON, S - Auburn University
item GANEGODA, J - Auburn University
item HOANG, T - Auburn University
item Torbert, Henry - Allen
item WILSON, A - Auburn University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2024
Publication Date: 3/26/2024
Citation: Hennessey, A.V., Mcdonald, M.B., Johnson, P.P., Gladfelter, M.F., Merrill, K.L., Tenison, S.E., Ganegoda, J.S., Hoang, T.C., Torbert III, H.A., Wilson, A.E. 2024. Evaluating the sensitivity of phytoplankton to copper sulfate pentahydrate at industry standard doses in hypereutrophic communities [abstract]. Auburn University Research Symposium, March 26, 2024, Auburn, AL.

Interpretive Summary:

Technical Abstract: Harmful algal blooms can cause severe economic and ecological problems in both natural and managed systems that often require toxic chemical treatments, such as copper sulfate pentahydrate (CuSO4·5H2O) to prevent damaging effects, such as fish mortality and the production of off-flavor compounds. Phytoplankton communities treated with copper sulfate pentahydrate are expected to become more tolerant to CuSO4·5H2O treatment, which could make blooms difficult to manage over time. To test this hypothesis, the toxic effects of CuSO4·5H2O were evaluated at a standard dose (348 µg/L Cu) and a low dose (174 µg/L Cu) relative to an untreated control. Treatments were applied once to 1,000 L mesocosm enclosures installed in a productive aquaculture pond at the start of the experiment and monitored for 28 days using the pollution-induced community tolerance (PICT) methodology, which measures photosynthetic efficiency across a broad range of 5 µg/L to 300,000 µg/L copper concentrations in acute short-term bioassays via effective quantum yield (QY), a measure of photosystem II efficiency. The results of the bioassay were applied to create half-maximal effective concentration (EC50) dose-response curves that can be utilized to determine sensitivity to copper. Results from this experiment indicated that both doses of CuSO4·5H2O resulted in >99% removal of cyanobacteria in the first 7 days and reduced cyanobacteria by at least 70% throughout the experiment. The low and standard doses had a higher tolerance than the untreated communities. Tolerance peaked three days after the treatments were applied and remained high for at least fourteen days. These data suggest that a lower dose of copper sulfate is equally effective at treating harmful algal blooms dominated by cyanobacteria with slower community tolerance build-up and that repeated treatments of copper sulfate might be least effective during the fourteen days after treatment. These conclusions could be transformational for informing water managers on the most effective methods for managing harmful algal blooms.