Effects of increased atrazine on growth and survival in early life stages of the Green Toad, Bufotes variabilis (Anura: Bufonidae)

The decline in amphibian populations is a well-known worldwide phenomenon related to multiple anthropogenic and natural factors such as climate, the introduction of exotic species, pollution and disease. There is a growing body of evidence that chemical contaminants are in some way responsible for amphibian declines. Atrazine, awidely used herbicide has drawn attention for its potential impacts on amphibians. Atrazine in naturally occurring freshwater has been reported to be relatively persistent and its widespread use, atrazine poses a latent chronic risk to exposed aquatic organisms. This study examined the effects of atrazine on growth and survival of embryo and larvae of green toad, Bufotes variabilis at seven concentrations of (0, 2, 7, 15, 25, 30 and 40 mg/L) during 25 days. The experimental results showed that the atrazine had a non-significant effect on hatching time and rate (p> 0.05) during the embryonic period. The results show average values for snout-vent length (SVL) for larvae was the highest in the control treatment (6.81±0.42 mm), followed by 2 mg/l (5.51±0.19), 7 mg/l (5±0.24), 15 mg/l (4.65±0.37) concentrations of atrazine, but this is not significant (p<0.05). After 18 days, larvae at atrazine over ≥25 mg/L appeared with signs of shrinkage and distorted appearance. The percentage of survival at the end of the experiment was 85.33%±4.61, 82.66%±4.61, 46.66%±28.37, 16.00%±4.38 and 0.00%, for the control, 2, 7, 15, 25 to 40 mg/L treatments, respectively. The results of ANOVA indicated the impact of atrazine on the survival of larvae B. variabilis was significant (p≤0.05).

Keywords:

Atrazine , Bufotes variabilis , Hatching rate , Development , Survival