Relative Toxicity of Waterborne Inorganic Contaminants to the Rio Grande Silvery Minnow (Hybognathus amarus) and Fathead Minnow (Pimephales promelas) in a Water Quality Simulating that in the Rio Grande, New Mexico

摘要

Point and non-point source discharges into the Rio Grande in New Mexico degrade water quality, which may adversely affect the only existing populations of the endangered Rio Grande silvery minnow (Hybognathus amarus). Laboratory studies were conducted to determine the relative toxicity of aluminum, ammonia, arsenic, chlorine, copper, and nitrate, individually and in an environmentally realistic mixture (excluding chlorine), to larval Rio Grande silvery minnow and larval fathead minnow (Pimephales promelas), a standard warm-water test fish. Larvae of both species were exposed to a given chemical in side-by-side tests to minimize temporal variability in test conditions. The test solutions were prepared in a non-standard reconstituted water that simulated the major water quality characteristics in the Rio Grande, New Mexico. The measures of acute toxicity were the median effective concentration (EC50) based on the combined effects of imparied mobility and death and median lethal concentration (LC50) based on death.