ABSTRACT: Within the class Reptilia, while relatively few diseases have been reported in wild populations of squamates and crocodilians, over the last ten years a variety of diseases have been seen in wild chelonians. Starting in the early 1980s there was a worldwide increased prevalence of fibropapillomas in populations of the green turtle, Chelonia mydas, with more than 50% of juvenile green turtles in certain populations affected. The causative agent of this disease and reasons for the worldwide epizootic remain unknown. In the mid-1980s moribund flattened musk turtles, Sternotherus depressus, with ulcerative lesions of the integument and pneumonia were identified in the Sipsey Fork in north-central Alabama, and several species of emydine turtles with proliferative shell lesions were seen in Lake Blackshear in southwest Georgia. A major decline in populations of the desert tortoise, Gopherus agassizii, in the western Mojave Desert was associated with an upper respiratory tract disease, and gopher tortoises, Gopherus polyphemus, with a similar disease have been seen at multiple sites in Florida. Declines of desert tortoises on the Chuckwalla Bench Area of Critical Concern, Riverside County, California, have been associated with an unusual shell disease. Is the sudden increase in the number of disease problems recognized in wild populations of chelonians merely coincidence, or are problems just being seen in a charismatic group of vertebrates? Because of their size and popularity as a research animal for studies in the field, chelonians may represent an excellent indicator species for fluxes in the quality of the environment in which they live.
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Direct Losses to Populations