Researchers Investigate New Lead in Mysterious Sea Turtle Disease

Scientists at the University of Central Florida are zeroing in on a new clue to understand a mysterious disease that affects about half the sea turtles in the Indian River Lagoon.

The infectious disease, known as fibropapillomatosis, causes tumors to grow inside and outside of sea turtles’ bodies. While the tumors may be benign, they can become debilitating if they obstruct the turtle’s internal organs or compromise its mobility or eyesight.

With help from a nearly $22,000 grant from the Sea Turtle Grants Program that is funded through sales of the Florida sea turtle specialty license plate, the scientists are surveying loggerhead and green sea turtles in the lagoon for the presence of major histocompatibility complex genes, which are part of the turtle’s immune system to fight off disease.

It is suspected that a turtle herpesvirus causes fibropapillomatosis, and the researchers are investigating why some turtles with the virus don’t have tumors.

One hunch they have is that turtles with a greater diversity of the genes may also be more likely to be tumorless despite having the virus.

“Theoretically, the more different types of MHC genes you have, the more different types of invaders you are able to bind to and thus protect the body from sickness and disease,” said Katie Martin, a doctoral student in UCF’s Department of Biology who is analyzing the potential connection as part of her research.

If the genes do dictate susceptibility to the disease, maybe turtles with a certain gene type never get the disease, Martin said.

“Or maybe we don’t see any pattern in particular, which would still be a result in and of itself, which would mean that even with MHC variation, it’s still not enough to modulate and fight off FP infection,” she said.

Martin said other factors may also play a role if the turtles develop tumors, including warmer waters; increased nutrient levels from runoff and inland sources; the drop in ocean pH from absorbing the greenhouse gas carbon dioxide; and pollution.

Martin is co-advised by Associate Professor Kate Mansfield and Assistant Professor Anna Savage, both with UCF’s Department of Biology.

Savage said the research is important for two reasons.

“On the conservation front, FP impacts approximately half of the coastal juveniles sampled in the Indian River Lagoon, and we still don’t fully understand its impacts on green sea turtle population health and viability,” she said.

“From a research perspective, we’ve seen a huge uptick in infectious diseases threatening a range of ectothermic vertebrates that depend on environmental temperature to maintain immune function, suggesting a link to climate change or other global processes.”

Martin will use UCF’s Marine Turtle Research Group’s database of more than 30,000 Indian River Lagoon sea turtle records dating back to the early 1980s and old, archived tissue from the past decades to look for potential associations between the genes and the presence of tumors. She and her research colleagues are also adding to the database by collecting new samples from turtles in the lagoon on a bimonthly basis.

Martin has a master’s degree in evolutionary biology from Stony Brook University in New York and a bachelor’s degree in biology from Fairfield University in Connecticut. She started at UCF this past fall and is interested in applying evolutionary concepts to conservation.

Savage runs the Savage Lab that studies disease genomics in amphibians and reptiles and is a member of UCF’s Genomics and Bioinformatics Cluster. She received her doctorate in ecology and evolutionary biology from Cornell University. She joined UCF in 2015.

Mansfield received her doctorate in marine science from William & Mary, Virginia Institute of Marine Science. She joined UCF in 2013 and directs the UCF Marine Turtle Research Group.