Implicated in about 30 percent of all North Carolina fish kills
BALTIMORE -- A global increase in harmful marine algae blooms over the past decade has coincided with increasing reports of death and disease for fish and, in some cases, of illnesses for humans.
Dr. JoAnn M. Burkholder, a North Carolina State University aquatic ecologist, is at the forefront of the study of these so-called "toxic algae." For the past five years, Burkholder has studied Pfiesteria piscicida, a microscopic marine organism responsible for killing millions of fish each year from Delaware to Alabama.
Burkholder's research has implicated P. piscicida, which inhabits brackish-water estuaries, in about 30 percent of all fish kills in North Carolina. (Piscicida means "fish killer.")
She and her colleagues also contribute to studies of the human health risks Pfiesteria piscicida may pose.
Burkholder presented her findings, "Role of Toxic Algae in Fish and Human Health," last Monday at the annual meeting of the American Association for the Advancement of Science, in Baltimore.
Their symptoms, which persisted for months, included memory loss, disorientation, mood swings, nausea and impaired immune systems
piscicida was first characterized by Burkholder in 1991. Laboratory research on it was halted two years later after she and an associate fell ill after prolonged and direct exposure to toxins the organism emitted during experiments. Their symptoms, which persisted for months, included memory loss, disorientation, mood swings, nausea and impaired immune systems.
"What happened was frightening, but ultimately, it convinced me that we had to continue the research and learn more about the effects this organism has on mammals as well as fish," says Burkholder, an associate professor of botany at NC State.
Her lab reopened last year with new state-of-the-art ventilation systems and isolation units for culturing the organism.
She is investigating several avenues of research, including:
"This dinoflagellate may be useful as an indicator of deteriorating water quality. What I hope will result from our research is that regulatory agencies will use the organism as a measure of estuarine stress," Burkholder says.
A predatory animal, P. piscicida goes through at least 19 different life stages and has the ability to steal green coloration from algae, allowing it to ambush fish while masquerading as a microscopic plant. It can eat holes as large as half dollars in its prey.
"Many features about this organism seem bizarre. We have video images of two dinoflagellates fighting over human blood cells, which were used in an experiment. The first organism attached to the blood cell and began to suck it up. Then another approached and began a tug-of-war for it," Burkholder says.
The dinoflagellate is most active in summer. In a test conducted in June 1994 within 300 feet of wastewater outlets in the Pamlico River, researchers found that 98 percent of fish gathered in three collections had been attacked and had large, open, bleeding sores.
To reduce health risks, Burkholder's new lab houses a fully contained isolation unit with a ventilation system capable of 12 complete air exchanges per hour. The air passes through three different filtering systems before it is discharged outside through a 10-foot stack, in compliance with federal standards.
The aquaria in which P. piscicida is grown are double-sealed, with ventilation ducts leading to a contained exhaust system. Researchers have no direct physical contact with the organism or its toxins, and researchers wear disposable gloves, boots and hair covers made of material that resists organic acids. Lab coats and reusable supplies are chlorinated after each use. No one works solo in the lab for more than one hour at a time.
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