Influence of N-nitrate pollutant on development of endemic common arboreal frog P olypedates cruciger (Amphibia: Rhacophoridae)

Abstract

Experimentally detected N-nitrate concentration in stagnant water bodies in Mirissa agro environs (0.1096mg'1) were tested on the development o f Polypedates cruciger under simulated natural conditions provided in the laboratory. Observations were mainly focused on behavioral changes, length o f different stages, mortality and growth changes during development and any abnormalities in the pre-adult stage. The detected N-nitrate concentration caused a significant impact on growth in tadpoles, especially in early life stages compared to the later stages o f the life cycle. Paired sample t-statistics revealed that mean wet weight o f young adults exposed to N-nitrate were significantly lower (p<0.05) than the non-exposed controls. In addition, early stage larvae exposed to the detected N-nitrate concentration did not achieve significant growth and may have had unseen impacts during their development. However, impacts o f N-nitrate lessened during the later stages o f life cycle such as the pre-adult stage. Present study revealed that even a low concentration o f N-nitrate in aquatic environments can cause an unseen impact on the amphibian population by altering the growth in highly sensitive developmental stages such as external gill stages.