Diazinon(R): Chronic Toxicity to, and Brain Acetylcholinesterase Inhibition in, the Sheepshead Minnow, Cyprinodon variegatus

Abstract

Abstract We investigated the toxicity of Diazinon to sheepshead minnows continuously exposed in flow-through toxicity tests. In the 96-hour acute test, a measured concentration of 1,400/ μg/liter was lethal to 50% of the juvenile test animals. In the partial life-cycle test, we also investigated uptake of Diazinon by sheepshead minnows and effect of Diazinon on brain acetylcholinesterase (AChE) activity. Average measured concentrations in the partial life-cycle test were nondetectable (control), 0.47, 0.98, 1.8, 3.5, and 6.5 μg of Diazinon per liter of seawater. Although the number of eggs spawned by continuously exposed fish was significantly reduced (α = 0.05) in all concentrations, no concentration tested significantly affected parental survival or fertility of eggs, nor were survival and growth of progeny affected in a subsequent 28-day test. Fish exposed to 0.47 μg/liter spawned 22.6 eggs/female-day, or 69% of control production (32.8 eggs/female-day). The number of eggs spawned by fish exposed to 6....