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Amphibians are sensitive to agricultural chemicals such as pesticides and fertilizers. Data on responses of anuran species commonly found in agricultural areas of Pakistan to chemical pollution are lacking. We studied the effects of ammonium nitrate on survival of tadpoles of common skittering frog (Euphlyctis cyanophlyctis). Tadpoles were collected from seasonal shallow water ponds formed during rainy season in the vicinities of Rawalpindi and Islamabad cities. Tadpoles were treated with ammonium nitrate at either 62.5, 125, 250, 500 or 1000 mg nitrate / l, and compared with a control group. Individual survival was significantly affected by increased ammonium nitrate treatments (P < 0.05), with survival rates after 18 days of exposure ranging from 83% at 62.5 mg NO3- / l to complete mortality at the highest ammonium nitrate concentration. The logistic regression model with individual survival as a binomial outcome variable and fertilizer concentration as independent variable explained 87% of the variance in survivorship (Nagelkerke R2), and correctly classified 94.0% of the cases (χ2 = 259, 5 d.f., P < 0.0005). Our lab-based findings suggest that ammonium nitrate at high concentrations may affect anuran species of Pakistan in croplands with extensive nitrogen-based fertilizer use. [ABSTRACT FROM AUTHOR]

The current study investigated metal concentrations (Zn, Cd, Pb, Mn and Fe) in the habitat and body tissues (blood, liver and kidney) of common skittering frog Euphlyctis cyanophlyctis along the Korang River, Islamabad, Pakistan. Samples were collected from three selected contaminated sites and a reference site at four different occasions from October 2010 to March 2012. All studied metals showed elevated levels in river water, as well as in blood, liver and kidneys of frogs from all contaminated sites. Specifically, Mn showed significantly higher levels in all analysed matrices from contaminated sites compared to the reference site. Histological sections of frog livers exposed to elevated metals showed abnormal hepatocytes, while their kidney sections showed discontinuous glomeruli with dead or ruptured cells exhibiting improper shapes with cytoplasmic depositions. This study indicates that frogs inhabiting Korang River are at potential risk of metal toxicity from the environment. [ABSTRACT FROM AUTHOR]