When sea turtles are awash in oil.

When sea turtles are awash in oil

Each year about 3.5 million metric tons of oil are spilled into the oceans -- rougly 1 metric ton for every 1,000 tons extracted, according to 1984 data from the environment directorate of the Paris-based Organization for Economic Cooperation and Development. Most of the resulting surface contamination occurs along ocean tanker lanes and coastal areas. Concerned that sea turtles might be affected by this oil, especially off their nesting beaches in the southern United States, the Interior Department commissioned a consortium of research institutions to conduct the first toxicological study of oil's effects on these aquatic reptiles--all of which are either endangered or threatened species.

The resulting data show that "the turtles' inability to avoid oil, combined with the fact that they were so strongly affected physiologically by the oil, is probably the worst combination they could have," says Sandy Vargo of the Florida Institute of Oceanography in St. Petersburg, which directed the research project.

In the physiological study, 12 turtles were forced to surface for air for two to four days through seawater covered by an oil slick either 0.5 or 0.05 centimeter thick. Affected animals developed a number of skin problems, including pretumorous changes, lesions and swelling. They also showed immune system changes, such as elevated white blood cell counts.

In a second set of tests, 20 turtles were placed in tanks in which half of the surface area was oiled and the other half was clean. "At best," Vargo says, "the turtles exhibited a weak avoidance of oil -- they really didn't seem to distinguish between the two on the basis of tactile, visual or chemical cues."

After the tests, each of the turtles was cleaned, fed, given antibiotics and put in rehabilitative care. Had they not gotten such intensive follow-up care, Vargo says, "they probably would have ultimately died."