The Effects of Urbanization on Dermal Corticosterone of Eastern Red-Backed Salamanders, Plethodon cinereus in Ohio

Abstract

We are currently amidst a 6th mass extinction event precipitated by anthropogenic alterations of the environment, specifically urbanization. There have been declines across all classes of vertebrates, however amphibians have suffered the greatest declines among vertebrates. Urbanization is among the most detrimental types of habitat modifications because as areas are converted and modified to meet human needs it increases susceptibility and exposure to disease and chemicals, increases the probability of encountering invasive species, alters climate and microclimates, and ultimately leads to decreased recruitment and population size in amphibian populations. This disrupts the moist, cool conditions many amphibians rely on for basic survival conditions, and if these conditions for reproduction and foraging are not met, alteration in behavior or physiological processes may be observed. In response to stressors, many amphibians release a stress hormone called corticosterone. Corticosterone helps amphibians respond to a stressor appropriately by suppressing acutely nonessential functions such as digestion, reproduction, and growth, thereby freeing energy for vital processes such as muscle metabolism. It has been shown that some species of salamanders respond physiologically to environmental changes, suggesting a link between habitat quality and physiological stress response that could be crucial for evaluating the effects of habitat alterations. This study looks at the physiological response of Eastern red-backed salamanders, Plethodon cinereus, living in urban and non-urban sites using a novel method of stress hormone collection. We found that salamanders living in urban sites had lower levels of dermal corticosterone than those living in non-urban areas. This finding could be explained by microclimate effects that differ at each site or by the effects chronic stress may be having on the salamanders in the urban sites.