The use of outdoor freshwater pond microcosms. III. Responses of phytoplankton and periphyton to pyridaben

Authors

  • Gary M. Rand,

    Corresponding author
    1. Ecotoxicology and Risk Assessment, Department of Environmental Studies/SERC, Florida International University, University Park, Miami, Florida 33199 USA
    • Ecotoxicology and Risk Assessment, Department of Environmental Studies/SERC, Florida International University, University Park, Miami, Florida 33199 USA
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  • James R. Clark,

    1. BASF Corporation, Agricultural Products Center, 26 Davis Drive, Research Triangle Park, North Carolina 27709 USA
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  • Catherine M. Holmes

    1. BASF Corporation, Agricultural Products Center, 26 Davis Drive, Research Triangle Park, North Carolina 27709 USA
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Abstract

An outdoor freshwater microcosm study was conducted in which pyridaben, an insecticide-miticide, was directly applied to water to determine its biological effects on phytoplankton and periphyton. Twenty-four microcosms (24 m3 each) were monitored for 11 months, then four treatments of pyridaben were applied two times at three concentrations (0.34, 3.4, 34.0 μg/L), including an untreated control. The succession of algal groups observed and the major genera found in microcosms during the baseline phase of the study were typical of oligo-mesotrophic systems in Florida. Following application of pyridaben, the most remarkable effect was a positive correlation of phytoplankton abundance with pyridaben concentrations in water; indicating increased abundance as a result of exposure. Both Chlorophyta and Pyrrophyta exhibited a significant increase (p=0.05) in population abundance at 3.4 and 34.0 μg/L pyridaben. Chrysophyta also elicited a trend of increased abundance at 34.0 μg/L, although the effect was not significant. The effects on phytoplankton populations were associated with the decline of zooplankton populations as a result of a direct effect of pyridaben exposure. There were no effects of pyridaben on periphyton communities or on functional endpoints. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 96–103, 2001

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