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.
