Effects of Chronic Zinc Exposure on the Growth, Sexual Maturity, Reproduction, and Bioaccumulation of the Guppy, Poecilia reticulata

A 134-d bioassay using sublethal quantities of zinc was conducted beginning with 5-d-old guppies, Poecilia reticulata. Five-day-old control fry had the highest whole body zinc concentrations (mg/g) which declined with growth; the zinc burden (mg/fish) increased primarily from 56 to 70 d during the onset of pregnancy. Uptake of zinc following zinc exposure occurred during logarithmic growth and pregnancy indicating that females actively transfer zinc to the embryo; 0.328 mg/L zinc triggered an apparent excretion process. Guppies exposed to 0.173 mg/L zinc for 70 d had significantly greater zinc body concentrations than controls. Acute sensitivity to zinc was correlated with the zinc body concentration. Growth in wet weight remained uniform for 28 d; however, after 134 d 0.607 mg/L zinc reduced the wet weight of females by 40%. The most sensitive indicator of toxicity was sexual maturity, after 70 d at 0.173 mg/L zinc, significantly fewer females had matured. At 0.607 mg/L zinc, fewer females (50%) gave bir...