Morphological and Physiological Effects of Ecological Light Pollution on Mammals and Amphibians in Pennsylvania

Open Access
Dananay, Kacey Lynn
Graduate Program:
Wildlife and Fisheries Science
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 28, 2012
Committee Members:
  • Jay Richard Stauffer Jr., Thesis Advisor/Co-Advisor
  • Ecological Light Pollution
  • Peromyscus leucopus
  • Desmognathus fuscus
  • artificial light
  • anthropogenic pollution
Ecological Light Pollution (ELP) is defined as an ecological problem caused by anthropogenic illumination, such as lights from automobiles, buildings, or natural resource burn-off flares. Ecological Light Pollution can affect reproduction, foraging, and behavior at varying degrees on a wide variety of taxa. The United States has the highest level of light pollution in the world from human infrastructure accounting for a 7 billion dollar expense. While many studies have shown artificial light can affect the environment, continued investigation of the population level and individual physiological effects of ELP are needed to guide conservation and management decisions in order to mitigate any negative effects. The three chapters presented here attempted to examine both the population effect on mice and the individual morphological and physiological effects of ELP on salamanders in Pennsylvania. Chapter I was an observational study looking at the population effect of artificial light on white-footed mice (Peromyscus leucopus) after long-term exposure. Live traps were used to determine the abundance of individuals in each site to test if more or less individuals inhabited areas with artificial light. Long-term exposure of artificial light did not significantly change the number of white-footed mice trapped. Moon phase also had no effect on the number of mice captured. The poor design and confounding variables, however, weakened the conclusions that could be drawn from this study. Chapter II focused on the morphological and physiological changes in salamanders caused by ELP. Using a quasi-natural mesocosm design, eight transects were built to test if artificial light affects growth or if it causes stress in salamanders. I found ELP caused no morphological or physiological change in northern dusky salamanders (Desmognathus fuscus). Chapter III focused on macroinvertebrate abundance between light and dark transects. Transects were constructed similar to Chapter II except for the addition of pitfall traps. Trapped macroinvertebrates were dried, weighed and separated into salamander prey and non-prey categories. Macroinvertebrate dry biomass was significantly higher in treatment transects with 24-hour exposure to artificial light. The overall conclusions drawn from these research projects were that future research should modify study designs to answer questions as to the morphological, physiological and population effects of ELP. Future studies should control for confounding variables, especially those surrounding light sources that are already present, ensure that the treatment is applied evenly across the study site and ensure lux and wavelength measurements of the light are recorded. Measuring light in both lux and wavelengths will standardize ELP research so that comparisons across studies can be made. Furthermore, having an additional measurement in wavelength is more biologically relevant because each wavelength can be perceived differently depending on the focal organism. Future research should especially focus on testing different wavelengths of light to determine what wavelengths attract or deter species of interest. Information like this can then be applied to outdoor lighting infrastructure in order to mitigate environmental changes associated with ELP. Few programs are helping to alleviate the effects of ELP on species other than sea turtle hatchlings. More research on the effects of ELP is ultimately needed so environmental programs can be designed and employed to mitigate any negative effects while protecting a wider variety of species from ELP.