Honolulu Star-Advertiser © Susan Scott
February 21, 2000
WHENEVER someone starts telling me a story about a sick turtle they saw, I know the question coming. “What are they doing about those tumors?”
The tone of this query is often impatient, even accusing, the implication being that “they” aren’t doing enough. Government biologists and wildlife managers, some people believe, don’t care.
This isn’t true. Since the 1980s, when the tumor disease fibropapillomatosis began increasing among Florida’s and Hawaii’s turtles, the National Marine Fisheries Service began studying the problem. The National Wildlife Health Center of the U.S. Geological Survey also began extensive work on this devastating turtle illness.
Since then, the two federal agencies have formed partnerships with each other and with workers worldwide. Such collaboration allows researchers from various areas and organizations to pool their efforts and share their findings about this disease, which currently plagues the world’s sea turtles.
To effectively join forces, turtle workers gather each year at the Annual Symposium on Sea Turtle Biology and Conservation. Last March, the 19th such symposium was held at South Padre Island, Texas. Much of the information presented at this meeting, as well as meetings past, is either about, or significant to, Hawaii’s turtles.
ONE study presented this year was conducted by an Ontario-based couple, Peter Bennett and Ursula Keuper-Bennett, under the guidance of George Balazs, the National Marine Fisheries Service’s turtle expert in Honolulu. This couple, so interested in sea turtles they have created a Web site called Turtle Trax (http://www.turtles.org), have been diving at Honokowai, Maui, each summer since 1988. During the dives the two photograph and videotape sea turtles, many of which have tumors.
After taking nearly 4,000 photos and 150 hours of videotape, the Bennetts and Balazs analyzed the material.
This was no small task. In order to tell individuals apart, the workers had to identify distinct patterns formed by the turtles’ face scales. The Bennetts also had to count, size and evaluate tumors as well as assess the sex, age and overall health of each turtle each year.
The results provide valuable new insights into the fight against this disease: Over time, the pictures showed, the tumors on about one-third of the diseased turtles became smaller or undetectable. Unfortunately, juveniles’ tumors rarely regress, and recovering males outnumber recovering females 3-to-1.
Do tumors that go away stay away? Only thousands of more pictures will tell.
The Bennetts’ study shows how hard it is to gather data among wild populations of marine animals.
But progress is occurring. For several years now, researchers have suspected that a marine virus is involved in these tumors. Now, another possible culprit has shown up.
Researchers studying the seaweeds that Hawaii’s turtles eat have found a dinoflagellate called prorocentrum sometimes living on the seaweeds’ surface. It produces okadaic acid, a natural toxin that promotes tumor growth in laboratory animals.
This discovery suggests that the turtles’ tumors might be initiated by a virus, then advanced when they eat this organism. Now, researchers must study the growth patterns of prorocentrum.
A struggling turtle covered with ugly tumors is a terrible sight to behold, and it’s reasonable to want something done for the poor creatures.
Something is.
Next week: Treating sick turtles.