Study connects Pfiesteria to 1997 fish kills

Virginia scientist presents findings that duplicate work of N.C. researcher

March 10, 2000|By Joel McCord | Joel McCord,SUN STAFF

A Virginia scientist has killed fish in a laboratory after creating toxic Pfiesteria piscicida, giving additional credibility to the work of other scientists who say the dinoflagellate was involved in 1997 fish kills on the lower Eastern Shore.

Harold Marshall, a researcher at Old Dominion University in Norfolk, reproduced the same experiments that Joanne Burkholder, the North Carolina State University scientist who helped discover Pfiesteria, had done in her laboratory.

Burkholder's critics have argued that her research was flawed because no one else had produced the toxic strain of Pfiesteria after it was connected with fish kills three years ago in the Pocomoke and Manokin rivers. About a dozen people also reported being sick after contact with the waters.

The results of his experiments are "verification," Marshall said after presenting his findings at a technical workshop yesterday on Pfiesteria at St. John's College in Annapolis.

"It was necessary for an independent laboratory to follow in the same vein to verify her research," he said, arguing it should "quiet" some of Burkholder's critics.

Burkholder, who also was at the workshop sponsored by the Department of Natural Resources, said that her critics don't understand how Pfiesteria works.

"To get it to go toxic, you have to know what you're doing," she said. "It's a complex creature. We know how to get it to kill and how to get it to come up again."

Before one of her presentations, Burkholder complained about scientists who have made "sweeping statements" disputing her findings.

"I've seen some situations that give me pause," she said. "But I would like to make a plea to stick to the data, stick to your areas of expertise."

While DNR scientists say Pfiesteria killed the fish in the Pocomoke, other scientists have advanced competing theories in a dispute that demonstrates the depth of the mystery surrounding the microbe and the volatility of high-profile science, with its fierce competition for grants and recognition.

Two of Burkholder's chief critics, Vicky S. Blazer, a fish pathologist with the U.S. Geological Survey, and Wolfgang Vogelbein, of the Virginia Institute of Marine Science, were scheduled to speak yesterday but canceled and could not be reached for comment.

During the workshop, scientists more firmly linked Pfiesteria with the fish kills.

Dave Goshorn, a DNR scientist, said there were seven major events involving fish with ulcerative lesions -- a sign of Pfiesteria -- and in "all cases Pfiesteria was present in the water."

In four of those cases, there was strong evidence the Pfiesteria was toxic, he said.

"That does not prove cause and effect between Pfiesteria and ulcers on fish in the field, but it does show a strong association of lesions and Pfiesteria," Goshorn said.

Burkholder said scientists at Long Island University found that Pfiesteria attacks oyster larvae as well as fin fish.

"Usually, oysters filter dinoflagellates such as Pfiesteria," she said. "But this is a complete reversal. Pfiesteria pries open the shell of the larvae and devours it within five minutes."

Eric Schwaab, of DNR, said he does not believe the discovery is "a cause for concern" in Maryland because the places where Pfiesteria has been active are not "prime oyster habitats."

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