Thermal Tolerance Limits and Effects of Temperature on the Growth and Development of the Green Toad, Bufotes viridis

Abstract. There is growing concern that climate change will have significant impacts on environmental quality and natural resources including amphibians. Among some data available on the effects of temperature changes on anurans, most studies have concentrated on adult individuals, and information is lacking on the effects of changed temperatures on the developmental patterns of anurans, including Bufotes viridis. To identify the range of temperature tolerance in B. viridis, we studied the effect of five temperatures (8, 15, 18, 25, 30°C) on the growth and development of the eggs of this species. Egg masses of B. viridis were collected from its natural habitat and placed in a designed aquarium with heating and cooling systems supplying a range of temperatures between 0 and 40°C. Sizes were measured and developmental stages identified relative to age to the early feeding tadpole stage (Gosner stage 25) at increments of temperature. The numbers of abnormal embryos and larvae were recorded at every temperature and thermal tolerance was recorded. A direct correlation was found to exist between temperature and growth and developmental rates. The results also confirmed that the developmental rate decreases with decreasing temperature. Larvae at stage 25 showed a significant difference in length only between eggs incubated at 8 and 30°C, respectively. It is concluded that developing eggs have a temperature tolerance from 12 through 25°C, and temperatures outside this range will reduce their survival rate.