Sea Bacterium Found Cause of Dolphin Deaths

NORFOLK, Va. —  Hundreds of dolphins that have washed ashore from Virginia to New Jersey this summer were killed by a common ocean bacterium, but scientists are uncertain why it was fatal to the mammals, a marine pathologist said today.

“We have a number of bacteria that we’ve isolated,” said Joseph R. Geraci, the head of a scientific investigative team.

Geraci told a news conference that the organism, vibrio, which killed more than 200 bottlenose dolphins, usually does not cause widespread death among the animals. He said the team will conduct further studies to see why the dolphins’ immune systems did not fend it off.

Geraci, an expert in wildlife disease at the University of Guelph in Ontario, Canada, also said no evidence has been found that the disease would endanger humans or other animals.

“I’m not unduly concerned that the condition we’re dealing with is transmissible,” Geraci said.

He said the dead dolphins have suffered brain hemorrhages and skin disorders. He also said the animals that washed ashore in New Jersey have had a milder form of the disease.

Geraci said vibrios exist in clean as well as unsanitary waters, but can flourish because of excess nutrients in water or unusually warm water temperatures.

Scientists are looking into the possibility that water temperatures in the mid-Atlantic region have been warmer than normal this summer.