Effects of copper on development of the fathead minnow,Pimephales promelas Rafinesque

Embryos of the fathead minnow, Pimephales promelas Rafinesque, were exposed to total copper concentrations (Cu_T) of 0.6, 61, 113, 204, 338 and 621 μg/l from 5 to 10 h post-fertilization through 2 days post-hatch. A decrease in hatching time was observed with increasing total copper concentration but there was no decrease in embryonic developmental rate. Therefore, embryos hatched at earlier stages of development. Significant (P ≤ 0.05) declines in percent survival and percent total hatch were observed at 621 μg/l Cu_T) but not at 338 μg/l Cu_T or lower concentrations. The percentage of embryos with abnormalities was greater at 338 and 621 μg/l Cu_T than at 204 μg/l Cu_T and lower concentrations.Individuals exposed to copper during early development were then exposed to the same test concentrations for 28 days post-hatch. Survivors at 113 through 338 μg/l Cu_T were at earlier stages of development than were control fish. The percentage of fish surviving decreased with increasing copper concentration over the range 61 through 204 μg/l Cu_T. The percentage of fish surviving at 204 μg/l Cu_T was not significantly different from that at 338 μg/l Cu_T, and there were no survivors at 621 μg/l Cu_T. Surviving larvae at all copper concentrations from 61 through 621 μg/l Cu_T showed decreased length, weight and coefficient of condition compared to controls. The percentage of larvae with abnormalities increased significantly with increasing copper concentration. The calculated 96-h LC₅₀ (larval stage) was 250 μg/l Cu_T and the 28-day LC₅₀ (larval stage) was approximately 123 μg/l Cu_T.