translate English to French: Elevated concentrations of nitrate from these sources can have both acute and chronic toxic effects on amphibians (Berger 1989; Baker and Waights 1993, 1994; Hecnar 1995).
Au Canada, on a observÃ© des dÃ©clins importants chez 17 des 24 espÃ¨ces de grenouilles et de crapauds rÃ©pertoriÃ©es et chez 21 espÃ¨ces de salamandres (Jacobs, 1999).