German U-boats stalked their prey off the Gulf and East coasts of the United States during World War II, sinking 148 petroleum tankers and countless other ships _ and spilling thousands of gallons of oil and gasoline into the ocean. Many of the tar balls that still wash up on the beaches of Florida and the rest of the Southeast are the result of slow leakage from some of the tankers sunk by the German submarines, said Fred Stroud, a senior on-site coordinator for oil spills for the U.S. Environmental Protection Agency.
But how much long-term damage was done to the environment?
Answers to environmental questions are sketchy because it has been almost a half-century since Germany unleashed the fury of its U-boats in 1942 in "Operation Drum Beat."
Environmental officials agree there probably was some short-term damage and in some cases sensitive areas may have been permanently damaged or destroyed.
But in most cases, oil degrades over a period of two to three years.
"That's not to say that we want oil spills in the environment, because there's always a certain amount of toxicity," said Stroud, who is based in Atlanta.
Oil can be especially devastating to mangrove stands and coral reefs, such as in South Florida, he said.
A spill also can have harmful effects on shellfish colonies, oysters, clams and shrimps in oceanside marshes, but Stroud said they usually recover within three years.
Temperatures and the natural action of the oceans help with the degradation process, he said.
When a spill is in the ocean, generally only the fish caught in the spill are affected, Stroud said, because the area is large enough to escape.
Birds, however, seem attracted to the spills.
Brian Milsap with the Florida Game and Fresh Water Fish Commission said 170 birds were known to have died in a 300,000-gallon oil spill near Jacksonville in 1987, and biologists believe five times that number may have perished.
The question of oil leakage from World War II tankers was raised by the U.S. government as early as 1967.
In that year, President Lyndon Johnson, concerned with the environmental damage to the European coastline when the Torrey Canyon ran aground, spilling 29-million gallons of oil, ordered a study to see whether oil leaking from the sunken tankers eventually could foul U.S. beaches.
The U.S. Coast Guard conducted underwater studies of the sunken tankers Gulftrade, R.P. Resor, Varanger and Coimbra.
No oil was found in the Gulftrade, Resor or Varanger.
The final ship surveyed was the British tanker Coimbra, situated 30 miles southeast of Fire Island, N.Y. Its tanks were intact, two of them closed to the sea. Divers entered the starboard tanks through hatches and discovered only residual traces of oil.
"Evidence gathered from this project indicates that tankers sunk during World War II do not present a potential pollution threat to the American coastline," the report said. "There is indication that a cargo will probably be lost from tanks through ventilation or other fittings before plating and other structure corrodes away," it said.
The German reign of terror on shipping began in January 1942, just weeks after the United States entered World War II.
Unarmed ships traveling up an down the East Coast and Gulf Coast were sitting ducks for the silent U-boats.
Edwin P. Hoyt, in his 1978 book, U-Boats Offshore. When Hitler Struck America, estimated that in one month of operation in early 1942, five German U-boats had cost the Allies 10,000 tanks of gasoline along with other supplies.
Early in the war, most of the attacks came at night, but a few months later the U-boats were becoming more bold.
On May 7, 1942, near Jupiter Inlet, a U-boat torpedoed the freighter Amazon in broad daylight. The same day, the tanker Halsey was sent to the bottom and the Java Arrow went down in the same area.
Gradually, the threat from the U-boats subsided as ships began traveling in convoys, submarine hunter-killers began perfecting their craft and pilots learned to drop depth charges properly.