Manatees depend on both natural and artificial warm water refuges like those found near coal-burning power plants to survive cold winters. As older coal-burning power plants are phased out in the next 10 to 20 years, researchers fear chronic exposure to cooler waters could weaken the large herbivores' immune system, and they could sicken or even die.
By sampling manatees' tear film in addition to performing other standard tests, scientists think they might be able to more efficiently evaluate manatees' immune system function and better determine strategies for rescue, treatment and rehabilitation.
The current tear analysis project, believed to be the first of its kind, builds on work UF veterinary scientists published recently in the journal Veterinary Ophthalmology that described the abundance of blood vessels found in manatee corneas. Blood vessels could have a tendency to move into the cornea to supply oxygen because the tear film creates a barrier so thick that oxygen present in air can't penetrate it, said Don Samuelson, Ph.D., a professor of ophthalmology in the Marine Mammal Medicine program at UF's College of Veterinary Medicine.
Manatees are believed to have the thickest tear film of any sea mammal, and possibly of any animal, Samuelson said. In general, mammals produce tears to protect against infection, because the eye itself does not have immune system components.
"Through this protection against the potential for infection, the manatee is able to enter murky waters just rich with potential pathogens," Samuelson said. "For that reason, we think this very thick tear film, undoubtedly rich with antimicrobial components, serves t
Contact: Sarah Carey
University of Florida