Heavy metals blamed in part for Pfiesteria toxin

Fish deaths struck Chesapeake Bay in 1990s

January 12, 2007|By CAPITAL NEWS SERVICE

Federal researchers said yesterday they have identified the toxin released by Pfiesteria, the microscopic marine organism blamed for mass fish killings and human health problems in the Chesapeake Bay and elsewhere in the late 1990s.

Peter Moeller, a chemist with the National Oceanic and Atmospheric Administration, studied the marine organism over the past seven years and said he has concluded that heavy metals - mainly a copper sulfur complex - cause Pfiesteria to release a toxin that stuns fish and destroys skin, leaving bloody lesions and causing death.

"I think metals and their involvement in toxicity in general has to some extent been greatly overlooked," said Moeller. He said he is not sure whether man-made pollution has played a role in the large amount of heavy metals in Pfiesteria-infested estuaries.

Pfiesteria has been blamed for killing millions of fish, most notably in Maryland, Virginia and North Carolina. A 1997 outbreak in the Chesapeake Bay was linked to memory loss in humans and quarter-sized lesions on dead rockfish.

Moeller said the combination of heavy metals and slow-moving, nutrient-rich water causes Pfiesteria to emit a short-lived but highly lethal toxin. The toxin lasts only a few days, and decomposes under bright light.

Pfiesteria experts said the study should end the debate within the scientific world as to whether the deadly toxin in fact exists. JoAnn Burkholder, a professor of aquatic ecology at North Carolina State University, was the first to propose the existence of a Pfiesteria toxin, arguing that it killed fish in her lab experiments.

Burkholder said there has not been a large outbreak of Pfiesteria for the past few years because of the severe sediment disruption of Hurricanes Isabel and Floyd, which drove the Pfiesteria cells into more open waters where they could not survive.

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