I heard that sea turtles are developing cancerous tumors

I heard that sea turtles are developing cancerous tumors at an alarming rate. What’s going on?

—Brendon Hunt, New York, NY

Sea turtles have long endured the pressures of hunting, intensive fishing practices and habitat degradation, including loss of nesting beaches due to human encroachment. In the last 20 years, marine turtles have also been the victims of a deadly tumor called Fibropapilloma, a bulbous growth that primarily affects the skin but also appears in the turtles” mouths, on their eyes and on internal organs.

The tumors can grow as large as a head of cauliflower, making it difficult for the animals to swim and find food. Internally, they can constrict the lungs and heart and affect the kidneys. In the 1980s, the disease began to reach epidemic proportions in shallow, near-shore waters off Hawaii, Florida and Barbados. The disease is now also present in Australia and the Pacific coasts of Mexico and Costa Rica.

The tumors have mostly been found on both young and adult green turtles, but have recently showed up on the Loggerhead, Hawksbill and Olive Ridley species. Sue Schaf of Florida’s Turtle Hospital, which treats and performs surgery on afflicted turtles, says, “We were seeing 50 percent of green turtles with tumors, but now it is closer to 70 percent and getting worse.” In Hawaii, some 60 percent of the turtles are affected.

While progress is being made to understand Fibropapilloma, scientists are still puzzled as to what is causing the tumors. Their high prevalence in marine habitats near areas of heavy human use would lead one to believe that some form of pollution is the cause, such as runoff from fertilizer or farm waste, but research has been inconclusive. Some scientists speculate that a virus might be giving turtles the disease. Other marine experts blame the tumors on global warming, with increased water temperatures weakening the turtles” immune systems.

CONTACT: Turtle Hospital, (305) 743-6509, www.turtlehospital.org; Florida Marine Research Institute, (727) 896-8626, www.floridamarine.org; National Marine Fisheries Service, www.nmfs.noaa.gov.