Effects of LED lighting on amphibian movement at Cuscowilla, Virginia June-July 2019 Open Access

Abstract

Amphibian populations are decreasing as a result of anthropogenic factors such as habitat fragmentation and pollution. The urbanization of amphibian habitat often includes introducing artificial light at night. Light pollution is believed to affect the behavior of amphibians. Currently sodium-halogen lamps are frequently used for lighting at night, however, there is a shift towards using Light Emitting Diodes as a greener alternative. Although this study took place in Cuscowilla, Virginia along the edge of a beaver pond with no previous artificial light exposure, the intention was to emulate an urban artificial lighting confrontation experience for pond-dwelling amphibians. At the chosen study location, five sites were set up with nine pitfall traps on each side of an erosion control fence. A lantern capable of emitting both high intensity LEDs and low intensity LEDs was placed centrally at each site to attract amphibians coming from and to the pond. For twenty nights each site’s lantern was randomly selected for high intensity, low intensity, or no light and left on for a period of two hours.

 

After the two-hour period, amphibians were identified and counted before traps were recovered. It was predicted that there would be a higher abundancy of amphibians found in pitfall traps located near high intensity LED sites in contrast to low intensity LEDs sites. Initial analysis determined that the data were non-normally distributed, therefor non-parametric Chi-squared tests using species counts (presence/absence trap success) were performed to determine if any species preferred one light intensity over the other. Only two species: Acris crepitans and Lithobates sphenocephalus were determined to respond significantly to the presence of LEDs over the absence. When conducting an additional non-parametric Kruskal-Wallis test using total amphibians collected, a significant difference between high intensity and no light treatment was found. A post-hoc Dunn test revealed that an additional species, Gastrophryne carolinensis significantly responded to LED presence over no light.

 

Table of Contents

1. Introduction .....................................................................................................................1

2. Methodology.....................................................................................................................5

2.1. Determining locations for study site.............................................................................6

2.2. Drift fence and pitfall traps...........................................................................................7

2.3. Sampling………………......................................................................................................9

2.4. Statistical Analysis......................................................................................................10

3. Results.............................................................................................................................12

3.1. Illumination.................................................................................................................12

3.2. Count data....................................................................................................................13

3.3. Abundance data...........................................................................................................14

4. Discussion.......................................................................................................................16

5. Conclusion......................................................................................................................19

6. References.......................................................................................................................21

9. Appendix........................................................................................................................42

About this Master's Thesis

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School	Laney Graduate School
Department	Environmental Sciences
Degree	M.S.
Submission	Master's Thesis
Language	English
Research Field	Biology, Conservation Biology, Ecology
Keyword	Urban Ecology Eastern Frogs Northern Cricket Frog Southern Leopard Frog LED Pollution Urban Light Pollution
Committee Chair / Thesis Advisor	John Wegner, Emory University
Committee Members	Gonzalo Vazquez-Prokopec, Emory University Lance Gunderson, Emory University

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