title: Effects of pulsed copper exposures on early life-stage Pimephales promelas.
abstract: Effects of pulsed copper exposures were investigated using Pimephales promelas aged less than 24 h in short-term chronic testing (7 or 14 d) with moderately hard synthetic water. Concentrations tested were between the species mean chronic value (22 microg/L at a hardness of 100 mg/L as CaCO3) and the 7-d continuous exposure EC50 for survival (40 microg/L) to examine exposures that were not acutely toxic and representative of actual wastewater discharge permit exceedences. Factors tested included pulse duration, recovery time between pulses, and pulse frequency. Survival was the main endpoint affected in all treatments (analysis of variance, p < 0.05). Effects on fish biomass, independent of survival effects, were observed in only 2 of 86 treatments examined. Fish survival was negatively affected at average copper concentrations between 7 and 50% of the 7-d continuous exposure EC50. Exposures having a 48- to 96-h recovery time between pulses had less effect on fish survival than did treatments with shorter (12-24 h) or longer (>120 h) recovery times. Results suggest that the criteria averaging periods used in the United States, and the averaging periods typically used in wastewater discharge permit limits for copper, may not protect against effects of certain pulsed exposures.
authors.affiliation: Tetra Tech, 400 Red Brook Boulevard, Suite 200, Owings Mills, Maryland 21117, USA. jon.bearr@tetratech.com
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Bearr
authors.forename: Jerry
authors.initials: J
authors.lastname: Diamond
authors.forename: Henry
authors.initials: H
authors.lastname: Latimer
authors.forename: Marcus
authors.initials: M
authors.lastname: Bowersox
mesh_terms: D000375:Aging / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D018533:Biomass; D003300:Copper / Q000633:toxicity*; D003530:Cyprinidae; D015996:Survival Rate
chemical_list: D003300:Copper