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Chronic toxicity of the bromoxynil formulation Buctril® to Daphnia magna exposed continuously and intermittently

August 1, 1993

Two chronic toxicity tests were conducted in which Daphnia magna were either continuously or intermittently exposed to bromoxynil octanoate (BO; as Buctril®) for 28 d. In the intermittent exposure test, daphnids were exposed to daily pulses of BO with 24-h mean concentrations equal to those in the continuous exposure test, and the peak concentrations were three times the 24-h mean values. After 28 d of continuous exposure to BO, survival of daphnids was reduced at 80 μg/L, whereas mean number of young per adult, intrinsic rate of natural increase, and mean weight of adults were all reduced at ⩾40 μg/L. Intermittent exposures to daily pulses of BO for 28 d caused reduced survival of daphnids at 24-h mean concentrations ⩾40 μg/L and reduced mean number of young per adult, intrinsic rate of natural increase, and mean weight of adults at 24-h mean concentrations ⩾20 μg/L. The estimated geometric mean-maximum acceptable toxicant concentrations of BO based on 24-h mean nominal values were 28 μg/L for continuous exposures and 14 μg/L for intermittent exposures. These results demonstrated that continuous-exposure studies may not be adequate in assessing herbicide toxicity to aquatic biota when concentrations fluctuate temporally.

Citation Information

Publication Year 1993
Title Chronic toxicity of the bromoxynil formulation Buctril® to <i>Daphnia magna</i> exposed continuously and intermittently
DOI 10.1007/BF00212126
Authors Kevin J. Buhl, Steven J. Hamilton, James C. Schmulbach
Publication Type Article
Publication Subtype Journal Article
Series Title Archives of Environmental Contamination and Toxicology
Series Number
Index ID 70178165
Record Source USGS Publications Warehouse
USGS Organization Columbia Environmental Research Center