Evaluating the response of Anura amphibians to the decreasing of water depth caused by climate change: investigating the growth, development and survival of green toad (Bufotes variabilis) larvae

Abstract

Introduction: The water depth in freshwater habitats, from ephemeral ponds to
permanent ponds and lakes, is changing due to various factors, including climate
fluctuations. In such environments, changing conditions usually produce
heterogeneous patterns of growth, metamorphosis, and reproductive timing. The
purpose of this study is to examine the effects of water depth level reduction on
growth size, age, and metamorphosis of green toad larvae (Bufotes variabilis).
Materials & Methods: The effect of reducing the water depth in two treatments with
moderate reduction and rapid reduction of water along with the control treatment was
investigated for 15 weeks. For this purpose, green toad larvae were placed in artificial
tanks with a density of 50 larvae in each tank with 4 repetitions under the same diet
until metamorphosis.
Results: The results of the experiment showed that the reduction of the water depth
in the fast and medium treatments increases the growth rate, reduces the duration of
metamorphosis and also reduces the survival rate compared to the control treatment.
Based on the statistical results, these effects are significant on the size and time of
metamorphosis, but insignificant on the survival rate.
Conclusion: Our experiment elucidates the understanding of an environmental
stressor on the situation of amphibians and shows how water fluctuations can affect
the status of species that rely on freshwater for development.