Kepone®: Chronic Effects on Embryo, Fry, Juvenile, and Adult Sheepshead Minnows (Cyprinodon variegatus)

Abstract

We investigated the toxicity of Kepone to, and uptake by embryo, fry, juvenile, and adult sheepshead minnows (Cyprinodon variegatus) using intermittent-flow toxicity tests. Concentration of Kepone and percentage of adult fish surviving in a 28-day exposure were: Control, 95%; 0.05 μg/liter, 95%; 0.16 μg/liter, 100%; 0.80 μ/liter, 78%; 1.9 μg/liter, 20%; and 7.8 μg/liter and 24 μg/liter, 0%. Concentration factors (concentrations in fish divided by concentrations measured in water) for adult fish averaged 5,200 (range 3,100 to 7,000). Symptoms of poisoning included scoliosis, darkening of the posterior one-third of the body, hemorrhaging near the brain and on the body, edema, fin-rot, uncoordinated swimming, and cessation of feeding. Adults surviving the first exposure were spawned, and the embryonic development, hatching, and survival and growth of fry and juveniles were monitored in a 36-day exposure to Kepone concentrations of 0.08, 0.18, 0.72, 2.0, 6.6, and 33 μg/liter. A significant number of embryos from adult fish exposed to 1.9 μg of Kepone/liter of water developed abnormally and died even when incubated in Kepone-free water. Kepone in water was not as lethal to progeny as to adults: 36-day LC50 for juveniles was 6.7μg/liter; 28-day LC50 for adults, 1.3 μg/liter. However, the average standard length of juvenile fish was significantly reduced by exposure to 0.08 μg of Kepone/liter of water; some fish developed scoliosis. Concentration factors in juvenile sheepshead minnows averaged 7,200 and increased from 3,600 to 20,000 as exposure concentrations decreased.