Factors Affecting the Immune System of the Ornate Box Turtle (\u3ci\u3eTerrapene ornata\u3c/i\u3e)

While many studies have detailed the complex intricacies of the endothermic immune system, relatively little is known about the immune system of ectotherms--specifically, reptiles. In an attempt to gain more knowledge about the factors affecting reptilian immune function, ornate box turtles (Terrapene ornata) were subjected to chronic stress in the form of high ambient temperatures in a semi-natural environment. It was hypothesized that chronic stress would lead to elevated levels of corticosterone in the blood, which would, in turn, suppress immune activity. It was found that body temperature and body mass in particular were significantly affected by chronic heat stress. Among turtles subjected to chronic heat stress, white blood cell to red blood cell ratios decreased and numbers of natural antibodies decreased--all of which suggests lowered immune activity. This decrease in immune activity correlated with increases in body temperature as well as body mass. Changes in corticosterone levels within and between both treatment groups were insignificant. Taken together, these results suggest that turtles subjected to chronic heat stress experienced improved health due to increased body mass, increased body temperature, and decreased immune function. This study reinforces the complexity of the stress response, and it highlights its far-reaching effects not only on immune function, but also on the body as a whole

Behavioral and Physiological Responses of Ornate Box Turtles (Terrapene ornata ornata) to Temperature Stress

Temperature is a critical regulator of physiological and behavioral processes. When body temperature departs from a preferred body temperature range there can be consequences to performance and survival. Therefore, extreme temperatures may initiate physiological responses and intensify trade-offs between key fitness functions such as foraging or predator avoidance. I explored the behavioral and physiological responses that ornate box turtles ( Terrapene ornata ornata), have to stressful environmental temperatures. First, I exposed adult female turtles to a range of temperatures which included 38°C, 28°C, 21°C, and 4°C and measured glucocorticoid hormone concentrations as an indicator of stress. I found that exposure to temperature extremes led to higher glucocorticoid concentrations. Second, I examined turtle thermoregulatory behavior (cover use) by comparing turtles with and without additional shade in an outdoor enclosure. I found that additional shade did not affect cover use, but that turtles with no shade had significantly warmer carapace temperatures and tended to lose more mass. I then challenged turtles with food limitation to see if thermoregulatory behavior and cover use would be altered. Although food limited turtles showed physiological signs of fasting (mass loss along with lower glucose and higher ketone body concentrations), they did not alter thermoregulatory behaviors or show increased glucocorticoid levels. Due to increased predation risks for small juvenile turtles, thermoregulatory decisions could differ between juveniles and adults. In separate studies, I investigated the responses of juvenile turtles when faced with a trade-off between thermoregulation and using a refuge. I found that juveniles were more likely to use a shelter even if shelter use resulted in body temperatures below preferred. These studies also indicated that larger juveniles were more willing to leave a refuge to thermoregulate. Together, these studies suggest that temperature is an important factor determining ornate box turtle behavior when faced with trade-offs, but the importance of temperature may diminish when more threatening stressors (predation) are present.

Behavioral and Physiological Responses of Ornate Box Turtles (Terrapene ornata ornata) to Temperature Stress

Temperature is a critical regulator of physiological and behavioral processes. When body temperature departs from a preferred body temperature range there can be consequences to performance and survival. Therefore, extreme temperatures may initiate physiological responses and intensify trade-offs between key fitness functions such as foraging or predator avoidance. I explored the behavioral and physiological responses that ornate box turtles ( Terrapene ornata ornata), have to stressful environmental temperatures. First, I exposed adult female turtles to a range of temperatures which included 38°C, 28°C, 21°C, and 4°C and measured glucocorticoid hormone concentrations as an indicator of stress. I found that exposure to temperature extremes led to higher glucocorticoid concentrations. Second, I examined turtle thermoregulatory behavior (cover use) by comparing turtles with and without additional shade in an outdoor enclosure. I found that additional shade did not affect cover use, but that turtles with no shade had significantly warmer carapace temperatures and tended to lose more mass. I then challenged turtles with food limitation to see if thermoregulatory behavior and cover use would be altered. Although food limited turtles showed physiological signs of fasting (mass loss along with lower glucose and higher ketone body concentrations), they did not alter thermoregulatory behaviors or show increased glucocorticoid levels. Due to increased predation risks for small juvenile turtles, thermoregulatory decisions could differ between juveniles and adults. In separate studies, I investigated the responses of juvenile turtles when faced with a trade-off between thermoregulation and using a refuge. I found that juveniles were more likely to use a shelter even if shelter use resulted in body temperatures below preferred. These studies also indicated that larger juveniles were more willing to leave a refuge to thermoregulate. Together, these studies suggest that temperature is an important factor determining ornate box turtle behavior when faced with trade-offs, but the importance of temperature may diminish when more threatening stressors (predation) are present.

Factors Affecting the Immune System of the Ornate Box Turtle (\u3ci\u3eTerrapene ornata\u3c/i\u3e)

While many studies have detailed the complex intricacies of the endothermic immune system, relatively little is known about the immune system of ectotherms--specifically, reptiles. In an attempt to gain more knowledge about the factors affecting reptilian immune function, ornate box turtles (Terrapene ornata) were subjected to chronic stress in the form of high ambient temperatures in a semi-natural environment. It was hypothesized that chronic stress would lead to elevated levels of corticosterone in the blood, which would, in turn, suppress immune activity. It was found that body temperature and body mass in particular were significantly affected by chronic heat stress. Among turtles subjected to chronic heat stress, white blood cell to red blood cell ratios decreased and numbers of natural antibodies decreased--all of which suggests lowered immune activity. This decrease in immune activity correlated with increases in body temperature as well as body mass. Changes in corticosterone levels within and between both treatment groups were insignificant. Taken together, these results suggest that turtles subjected to chronic heat stress experienced improved health due to increased body mass, increased body temperature, and decreased immune function. This study reinforces the complexity of the stress response, and it highlights its far-reaching effects not only on immune function, but also on the body as a whole

PRELIMINARY ANALYSIS OF THE EFFECT OF TEMPERATURE ON OVERWINTERING PATTERNS IN EASTERN BOX TURTLES (TERRAPENE CAROLINA) **

In ectothermic animals, environmental temperatures cause alterations in activity, cellular metabolism, and physiological processes. To compensate for nonoptimal temperatures and resource scarcity that often accompany seasonal patterns, some ectotherms undergo brumation, during which their metabolism is slowed to conserve energy needed for future emergence, growth, and reproduction. Globally, winter temperatures are becoming milder, with January 2020 being the hottest January on record, and January 2016 the second hottest. Warmer temperatures during brumation can increase mortality or decrease fitness in ectotherms by increasing metabolism during over-wintering, which can cause significant body mass loss. Mild temperatures may also interfere with physiological mechanisms that regulate emergence from over-wintering. Early emergence presents a risk to ectotherms as spring food sources may not be available, and they may be unable to burrow to safe depths to avoid sudden decreases in temperature that can occur in spring. Body mass losses compounded with early emergence could hinder reproduction which could affect population persistence. Turtles make up a large group of ecologically significant ectotherms since they contribute a wide variety of ecosystem services, including soil maintenance, ecosystem restoration, and seed disbursement. Despite their importance however, many turtle populations are experiencing declines and research on turtles is lacking, especially during overwintering periods. Since 2013, we have documented overwintering patterns and locations in a population of Eastern Box Turtles (Terrapene carolina) in northeastern Georgia using radiotelemetry. In 2019, we added temperature data loggers (iButtons ®) that record environmental and individual turtle temperatures every 3 hours. We plan to observe emergence from brumation and its relationship with temperature in Eastern Box Turtles to increase our understanding of how temperature fluctuations could influence overwintering activities in ectotherms