title: Lethal and Sublethal Effects of Nitrogen Fertilizer Ammonium Nitrate onCommon Toad (Bufo bufo) Tadpoles
abstract: The impact of elevated ammonium nitrate concentrations onthe survival and development of common toad (Bufo bufo) tadpoles wasinvestigated in the laboratory. 1,704 mg/L and 1,637 mg/L nitrate (equivalentto 2,198.7 mg/L and 2,112.3 mg/L ammonium nitrate) were recorded as 96 h and168 h LC50s respectively. These are well above field levels (10-250 mg/L)observed in freshwater in Britain. The exposure of tadpoles to nominalconcentration of 100 mg/L nitrate for 24, 48, and 72 h caused a significantdecrease in their activity but no clear reduction in food consumption ordelay of the development. In subchronic exposures at the nominalconcentrations of 50 and 100 mg/L nitrate, the metamorphosis started earlierand took less time to complete than in the control. However, some of theresults were equivocal, at 50 mg NO3/L the metamorphs weresignificantly larger than the controls, while at 100 mg NO3/Lmetamorphs were not significantly different from the controls. Certaindeformities and unusual swimming patterns were also found in tadpoles exposedto various concentrations of ammonium nitrate.
authors.affiliation: Department of Biological Sciences, De Montfort University, Scraptoft, Leicester LE7 9SU, United Kingdom
authors.initials: Q
authors.lastname: Xu
authors.initials: RS
authors.lastname: Oldham