KAHN, P.F.**; MENDONCA, M.T.; Auburn University, Auburn, Alabama; Auburn University, Auburn, Alabama: Seasonal Changes in Sex Steroids of the Gopher Tortoise (Gopherus polyphemus) and Their Relationship to Upper Respiratory Tract Disease

Anthropogenic factors have contributed substantially to the decline in threatened gopher tortoise populations. However, disease may also be a considerable threat to the survival of this species. Gopher tortoises are susceptible to Upper Respiratory Tract Disease (URTD), a bacterial infection cased by Mycoplasma agassizii. It is well established that the endocrine and immune systems are highly integrated in vertebrates; hence, physiological responses to disease can affect the production and release of sex steroids. Therefore, while low recruitment rates in gopher tortoises are primarily the result of nest and hatchling predation, it is important to monitor sex steroids in these animals to determine if URTD has deleterious effects on reproductive function. In this study, blood samples were taken from gopher tortoises at Fort Benning, Georgia, during spring and summer sampling periods. The blood samples were analyzed for the presence of antibodies to M. agassizii using an ELISA. In addition, we conducted radioimmunoassays to measure circulating plasma levels of testosterone (T) in males and 17�-estradiol (E) in females. We hypothesize that symptomatic tortoises with low antibody titers will exhibit seasonally uncharacteristic sex steroid levels.