Influence of nickel chloride, chlorpyrifos, and imidacloprid in combination with different temperatures on the embryogenesis of the zebrafish Danio rerio.

Two independent types of stressors, chemicals and high temperatures, which frequently act together in the environment, are addressed in this study. Pesticides (imidacloprid and chlorpyrifos) as well as a metal salt (nickel chloride) were investigated for their toxic effect at different temperatures. Tests focused on the early development of zebrafish (Danio rerio) embryos and larvae (from fertilization up to 168 h postfertilization) when exposed to the three respective chemicals at an optimum temperature (26 degrees C) and three higher temperatures (up to 33.5 degrees C). At all temperatures tested, the two pesticides did not have a significant impact on the early development of the zebrafish at the highest test concentrations (imidacloprid, 50 mg/l; chlorpyrifos, 1 mg/l). Nickel led to a significant decrease of hatching success at all temperatures; the combination of elevated temperature and nickel exposure revealed a synergistic effect of both stressors.