Columbus Center targets Pfiesteria Goal is to combat microbe that has killed fish, sickened people

September 20, 1997|By Christian Ewell and Douglas M. Birch | Christian Ewell and Douglas M. Birch,SUN STAFF Sun staff writer Timothy B. Wheeler contributed to this article.

Scientists at Baltimore's Christopher Columbus Center plan to launch a crash program aimed at combating Pfiesteria piscicida, the single-celled predator that has attacked fish in Maryland and Virginia tributaries of the Chesapeake Bay.

"We're going to take this very seriously," said Yonathan Zohar, who is in charge of research at the University of Maryland's Center of Marine Biotechnology at the Columbus Center. "We're mobilizing lots of equipment, millions of dollars of equipment."

Over the next several weeks, they hope to equip three laboratories at the Inner Harbor research center to safely handle Pfiesteria piscicida.

The marine organism, when in the presence of large schools of fish, produces potent toxins that have killed and sickened fish in the Pocomoke and Chicamacomico rivers and Kings Creek on the Lower Shore, and in two Virginia waterways. The toxins can cause memory loss, skin irritation and respiratory problems in people.

Zohar said the aim is to learn more about Pfiesteria's complex life cycle and to raise it in the laboratory so that it can be more easily studied. Columbus Center scientists also hope to use DNA technology to develop a test, called a molecular probe, to quickly screen water samples for the presence of the organism.

Dr. Rita Colwell, head of the University of Maryland Biotechnology Institute in Baltimore, said the new Pfiesteria program will cost $300,000 to $400,000 over the next several years. She said she hoped the research would help scientists determine exactly what the organism is and compare it with the strain that was discovered in North Carolina.

Columbus Center officials also plan to install soon in the center's Hall of Exploration an exhibit on Pfiesteria and similar organisms, called dinoflagellates.

Biologists in a number of other states are studying Pfiesteria, but only two marine laboratories have the safety equipment needed for protection from the organism in its most toxic stage, said Dr. Edward Noga of North Carolina State University.

Both of those laboratories are at North Carolina State University, which announced Thursday that it would build a $1 million research center exclusively for work on Pfiesteria.

"There's definitely a need for more research on this organism, and one of the major limitations is the facilities," said Noga. "You just can't work with it in a normal aquaculture laboratory."

Pfiesteria, discovered by Noga and Dr. JoAnn Burkholder in North Carolina in 1988, acts like a plant in some ways, like an animal in other ways. It has at least 24 life stages, and the largest is hundreds of times bigger than the smallest.

Unlike other toxic marine microorganisms, Pfiesteria appears to stalk and attack its prey deliberately with chemical weapons. It may produce a dozen toxins, which apparently fall into two broad categories.

One type of toxin appears to attack the central nervous system of the fish, disorienting them and causing them to swim in a confused, spiraling pattern. The second type seems to dissolve the fish's skin, acting like an acid that eats away at the flesh.

Scientists at the Center of Marine Biotechnology say they will work with other scientists at the University of Maryland Medical Center to study the human health effects of the toxins, Zohar said.

Dozens of Marylanders have complained about getting sick after coming in contact with fish with sores or lesions like those inflicted by Pfiesteria, or after working or playing in and around the water where fish with similar injuries are dead or dying.

Maryland scientists want to identify the microbe's toxins, Zohar said. They also hope to determine how and why it sometimes transforms itself from a harmless, bottom-living vegetarian into a free-swimming carnivore.

As part of that research, scientists hope to determine if there is a link between the seemingly sudden appearance of the microbe in East Coast waters and rising levels of nutrients in Chesapeake Bay estuaries.

Now, identification of the microbe is a laborious task. Scientists place suspected microbes in the water with fish, and wait to see if the fish are attacked. Or they try to recognize Pfiesteria under the electron microscope.

"We hope to quickly develop molecular detectors to go out and quickly identify and localize a possible Pfiesteria presence anywhere, even in it's dormant stages," Zohar said.

Converting the Columbus Center's labs will cost about $30,000, center officials said. Part of the money will be for installing light fixtures and ceiling tiles that can be washed without absorbing water.

Part will pay for improving the laboratories' ventilation system, which screens out biological materials. "I'd rather stand next to the exhaust here than stand next to one of those rivers," said William J. Cooper, assistant director of the Center of Marine Biotechnology.

Zohar said scientists would be careful when handling the organism but that they aren't afraid of it. All of the center's researchers have experience "dealing with organisms that can be nasty," he said.

Colwell said part of the research will be paid for through a $75,000 emergency grant from the U.S. Food and Drug Administration. Center scientists are seeking a $50,000 grant from the National Institute of Environmental Health and Safety.

Pub Date: 9/20/97

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