UF researchers embark on major multidisciplinary project to shed light on spread of respiratory disease in tortoises

Published: June 26 2002

Category:Health, Research, Veterinary

GAINESVILLE, Fla. — Building on 10 years of research into an upper respiratory tract disease that has devastated endangered tortoises across the United States, University of Florida scientists hope a new $2.2 million federal grant will help them better grasp how various chronic diseases spread in the animals as well as in people.

Funded by the National Science Foundation, the Florida-based project is one of the largest of its kind ever awarded for this type of research involving wild animal disease as a model for understanding not only the impact on humans but on the entire ecosystem.

“The tortoise is unique, as it has about the same life span as a human and reaches reproductive age at about the same time,” said Mary Brown, a professor of pathobiology at UF’s College of Veterinary Medicine and a principal investigator. “Lots of changes have occurred in the tortoise’s habitat, many of which are human-induced. We are interested in learning more about how natural factors combine with human-induced ones, such as relocation and fire exclusion, and how those relationships interact with biological and microbial factors to determine the incidence and spread of disease.”

In the first year of the new project, a team of experts led by Brown and colleague Paul Klein will survey more than 700 tortoises at 30 Florida sites to determine population characteristics, habitat quality and upper respiratory tract disease status at each location. The sites include state parks, water management areas, military reserves, state mitigation parks and private holdings.

In subsequent years, they will focus on 12 of these sites using ecological, molecular and other diagnostic tools to determine the influence of anthropogenic, or human-induced, factors in disease spread and virulence. Researchers expect these multidisciplinary approaches to shed light on how respiratory disease in its various stages affects gopher tortoise populations. They also hope to develop mathematical models in order to predict the effect these multiple, complex factors have on disease spread.

“Infectious diseases are an ever-present risk to wildlife, particularly during situations in which animals are removed from their natural habitats for captive breeding programs or during conditions of stress, such as release into new habitats or encroachment into their habitats by urbanization,” Brown said. “This is even more important when the species concerned is a keystone species, such as the Florida gopher tortoise, that is critical to ecosystem health.”

As many as 360 animal species depend on the gopher tortoise for survival, including other threatened species such as the indigo snake.

“Without the gopher tortoise, the biological diversity of upland habitats would be greatly diminished,” said Klein, a professor and comparative immunologist in the UF College of Medicine who has a joint appointment in the veterinary college’s department of pathobiology. “Furthermore, in a long-lived species that does not attain reproductive maturity for 10 to 20 years, a single catastrophic event such as a disease epidemic could reduce a population to the point that recovery would be extremely difficult.”

Such an event has happened to the threatened desert tortoise of the American Southwest, according to Kristin Berry, a biologist with the U.S. Geological Survey who first brought the respiratory disease, called mycoplasmosis, to the attention of the UF group a decade ago.

“We have experienced catastrophic declines,” Berry said. “We have lost at least 90 percent of our breeding tortoises in some populations, and in some of these groups, mycoplasmosis has played a role. It’s going to take decades, if not centuries, for us to see recovery.”

Brown, Klein and others at UF who have studied this disease in both the gopher and desert tortoises, were first to identify the mycoplasma bacteria as the disease-causing agent. The group amassed data on several key populations of the gopher tortoise in Florida, “an important foundation for the current research,” Brown said.

“It is exciting that the National Science Foundation is realizing the role of disease in the ecology of wildlife,” Brown said. “They are recognizing that in general, microbial infections in wildlife populations could have an impact on human populations, and that understanding how the disease spreads and what factors affect microbial virulence is very important.”

She added that the UF team’s overall goal is to provide better information to state and federal wildlife management agencies in order to assist them make decisions. In addition to Brown and Klein, experts in reptile medicine and biology, habitat assessment, population dynamics and modeling are contributing to the project.

“If we can provide better answers regarding the impacts of tortoise relocation, for example, these agencies might be able to make better management decisions,” Brown said.

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Writer
Sarah Carey

Category:Health, Research, Veterinary