Date of Award

5-2022

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Lisa Hazard

Committee Member

Scott Kight

Committee Member

Matthew Schuler

Abstract

Road salt, which is used as a roadway deicer in the winter time, is a major contributor to the salinization of freshwater habitats. Amphibians are particularly vulnerable to the salinization of aquatic environments due to the reliance of many species on pond, lake, and stream habitat in their aquatic larval stage. This study examined how Northern Gray Treefrog (Hyla versicolor) tadpole behavior is affected by salinity in a multiple t-maze. Alternate turning is sequential turning in opposite directions. Alternating turns lead the animal further from the starting point, and are innate behaviors associated with foraging, exploration, and escape. A multiple t-maze is a complex maze environment where an individual can make zero to three alternating turns. At elevated salinity H. versicolor displayed more alternating turn behavior than expected if turns were made randomly. However, there were no differences among salinity levels in alternating turn frequency, which suggests that tadpoles will continue to move directionally straight regardless of salt concentration. At elevated salinities, tadpoles were more likely to complete the maze within five minutes, spent less time completing the maze, and were more likely to make 180o turns (u-turns). Prior salt exposure from earlier pilot studies significantly reduced the frequency of alternating turns and reduced the rate of maze completion. Further studies are warranted to determine how brief prior exposure affected turning behavior. In a t-maze binary turning bias test, tadpoles exhibited a trend of lateralized turning bias that was also evident in the multiple t-maze trials. These effects could have implications for how H. versicolor tadpoles forage, explore and evade predators in their natural habitat. This protocol for exploring escape behaviors in a multiple t-maze can be applicable for studies of other amphibian species or to determine the effects of other chemical stimuli such as predator cues and pesticides on behavior.

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