Viral Epidemic Suspected in Dolphin Deaths Off Spain

Dead dolphins are washing up on Spain’s eastern Mediterranean coast in unusually high numbers, causing marine biologists and ecologists to suspect a viral epidemic is killing them.

Many scientists and environmental activists believe the deaths are the inevitable outcome of large-scale dumping of toxic pollutants in the Mediterranean by petrochemical plants.

Esteve Grau, a University of Barcelona biologist, said preliminary results of autopsies on three of the dead mammals showed extremely high levels of polychlorinated biphenyls, or PCBs.

“We’re working on the hypothesis that the dolphins ate PCB-contaminated fish and that this severely weakened their immune systems, making them susceptible to a still-unidentified virus,” Grau said in a telephone interview.

PCBs are liquid, resinous or crystalline organic compounds used in industrial processes as lubricants, heat-transfer fluids or to give strength or flexibility to wood, metal or concrete.

“We believe the scientists’ hypothesis to be correct,” said Xavier Pastor, head of the Greenpeace environmental group’s office in Palma, capital of the Spanish island of Majorca in the Mediterranean.

He said the toxicity of PCBs and their resistance to decomposition make them especially dangerous to mammals.

“The epidemic appears similar to others that killed up to 800 seals in the North Sea off the Netherlands in 1988 and in another case under study in California,” Pastor said.

He said some of the dead dolphins had been found on beaches near Palma, in the Balearic archipelago 150 miles south of Barcelona.

Grau and other scientists from the Barcelona Zoo, the Marineland Aquatic Park and the University of Valencia have conducted 10 autopsies on dolphins. They are trying to determine why only striped dolphin, and not fish, have been killed, he said.

Joaquim Piza of Marineland said doubts remain about whether PCBs caused the dolphins to die.

“If that were the case, it’s most likely dolphins of other species would have been affected,” he said.

“The autopsies have not produced conclusive evidence that the PCBs are the cause. The only thing we have been able to determine so far with certainty is that the dolphins suffered a weakening of their immune systems.”

Piza said there was some speculation the dolphins had contracted a herpes-type virus that attacked their immune systems.

Between 12 and 20 infirm or aged striped dolphins are found washed up every summer on Spain’s eastern beaches and on Majorca, Grau said, but there have been more than 100 this year. He said the striped dolphin is not an endangered species and is abundant in the Mediterranean.

Scientists fear that the presence of PCBs eventually may reduce the number of dolphins by affecting reproduction in addition to killing the weaker ones, Grau said.

“We estimate that only 1% of affected dolphins have washed up,” he said, “which means the total number that have succumbed to the viral epidemic could be as high as 10,000.”

Pastor noted that industrial and chemical companies continue dumping tons of toxic waste, including PCBs, into the Mediterranean from plants along Spain’s Mediterranean coast from Barcelona to Algeciras, adjacent to Gibraltar.

“We’ve called on Spain’s autonomous regional governments and the central government in Madrid to set up a plan to gradually, but definitively, end all industrial toxic waste dumping into the Mediterranean by the end of 1991,” he said.

“We’ve tried to work with industrial companies directly, but they have refused to acknowledge how much they dump into the Mediterranean, saying it might reveal industrial secrets to competitors.”

He said Greenpeace had found it difficult to develop estimates of the amount of PCBs companies in Spain dump into the Mediterranean.