Growth and Survival of Salamanders Exposed to Different Formulations of Glyphosate-based Herbicide
Grade Level at Time of Presentation
Senior
Major
Biology and Environmental Health Science
Minor
-
Institution
Western Kentucky University
KY House District #
N/A
KY Senate District #
N/A
Faculty Advisor/ Mentor
Jarrett Johnson, PhD
Department
Biology
Abstract
Amphibian populations have been experiencing rapid declines worldwide in the past few decades. There are many proposed causations, including the use of agricultural chemicals such as herbicides. Glyphosate based herbicides are one of the most widely used herbicides. This study looks at the effects of different brands of glyphosate based herbicides, including those intended for aquatic use, on the survival and growth of axolotl salamander larvae. Out of the four brands of glyphosate herbicide (Aquamaster, Aquaneat, Helosate plus, and Roundup Pro), the survival rates of Roundup Pro were the lowest. Most mortality occurred between the 3 mg/L and 6 mg/L concentrations, during which all those treated with Roundup Pro died. The growth, measured in terms of total snout to tail length and also head width, appeared to be greatest in length for those larvae treated with Aquaneat brand herbicide. These results indicate that Roundup Pro is lethal at concentrations of 6 mg/L, and that the composition, which includes a surfactant, may be responsible. We subsequently tested the concentration at which different adjuvant surfactants meant for use with aquatic safe herbicides (Dyne-Amic, Kinetic, and Cygnet) affected larval growth and survival and compared results with Roundup Pro. The larvae exposed to the initial 5 mg/L concentration of Roundup Pro had total mortality, but survival was unaffected by exposure to aquatic safe surfactants at low concentrations. At high concentrations, Dyne-Amic and Kinetic significantly increased larval mortality while Cygnet did not. Of the surviving larvae, there was no difference in growth. The findings of this study are significant in that they give insight regarding how the use of herbicides could be contributing to the decline of amphibian populations.
Growth and Survival of Salamanders Exposed to Different Formulations of Glyphosate-based Herbicide
Amphibian populations have been experiencing rapid declines worldwide in the past few decades. There are many proposed causations, including the use of agricultural chemicals such as herbicides. Glyphosate based herbicides are one of the most widely used herbicides. This study looks at the effects of different brands of glyphosate based herbicides, including those intended for aquatic use, on the survival and growth of axolotl salamander larvae. Out of the four brands of glyphosate herbicide (Aquamaster, Aquaneat, Helosate plus, and Roundup Pro), the survival rates of Roundup Pro were the lowest. Most mortality occurred between the 3 mg/L and 6 mg/L concentrations, during which all those treated with Roundup Pro died. The growth, measured in terms of total snout to tail length and also head width, appeared to be greatest in length for those larvae treated with Aquaneat brand herbicide. These results indicate that Roundup Pro is lethal at concentrations of 6 mg/L, and that the composition, which includes a surfactant, may be responsible. We subsequently tested the concentration at which different adjuvant surfactants meant for use with aquatic safe herbicides (Dyne-Amic, Kinetic, and Cygnet) affected larval growth and survival and compared results with Roundup Pro. The larvae exposed to the initial 5 mg/L concentration of Roundup Pro had total mortality, but survival was unaffected by exposure to aquatic safe surfactants at low concentrations. At high concentrations, Dyne-Amic and Kinetic significantly increased larval mortality while Cygnet did not. Of the surviving larvae, there was no difference in growth. The findings of this study are significant in that they give insight regarding how the use of herbicides could be contributing to the decline of amphibian populations.