Watch Out For Killer Algae

by Kieran Mulvaney

Originally published in E Magazine, March/April 1996.

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Imagine a microscopic predator which can spend years at a time without food but which, when conditions are favorable, suddenly emerges from the sediment, changes shape and kills millions of fish after stunning them with a poison so powerful it can cause immuno-suppression in humans. Find it hard to believe? Go tell it to Dr. JoAnn Burkholder.

Dr. JoAnn Burkholder, a freshwater botanist at the North Carolina State University, is the person who first discovered and described the phytoplankton species, Pfiesteria piscicidia, when it began killing fish in a university aquarium several years ago. And she's used to people not believing her.

According to Dr. Burkholder, Pfiesteria spends much of its life as harmless-looking, microscopic cysts in the sediment. But introduce large numbers of fish and, under the right conditions, it undergoes a transformation out of a science-fiction movie.

In minutes, the cysts turn into what Dr. Burkholder calls toxic flagellated vegetative cells and propel themselves towards the fish. They stun the fish by unleashing a powerful toxin and then, after the fish die, transform themselves into large amoebae, and eat the carcasses. As they are feasting on the fish, they are photosynthesizing, using chloroplasts they've "stolen" from algae they have eaten previously. The feeding frenzy over, they revert to their cyst form and return to the sediment.

Phytoplankton aren't supposed to behave like that. In fact, no form of life is supposed to behave like that, and Dr. Burkholder freely admits it's hard to swallow. But she, more than anyone, is acutely aware of just how real Pfiesteria and its toxins really are.

One day early in her research, after spending three hours in her laboratory's small environmental chamber, gently pouring culture containing the algae into a flask, Dr. Burkholder became steadily disoriented; she began to suffer from stomach cramps and underwent an asthma attack. Her eyes became so bloodshot that for a couple of days she found it difficult to see. For eight days, she lost her short-term memory. More recently, her colleague, Dr. Howard Glasgow, received such heavy exposure to the toxin that he was hospitalized and is no longer able to work directly with the algae for fear of further exposure.

The university now rates her work a level 2 biohazard, slightly below that of AIDS and on a par with rabies. Several years on, Dr. Burkholder regularly suffers from bronchitis and pneumonia, and can no longer exercise strenuously without suffering further relapses; she now approaches her subject only when covered from head to toe with protective laboratory clothing and wearing a full-face- mask respirator.

Pfiesteria produces extra gametes in the presence of phosphates, which makes the rivers and estuaries of North Carolina especially suitable for its growth. Phosphate concentrations in the North Carolina region are naturally high, and over the last five years, North Carolina's hog industry has grown from the seventeenth-biggest to the second-largest in the country, generating an attendant increase in nutrient-rich effluent spills. Altogether, North Carolina is reckoned, by some estimates, to be the number one state in the country in terms of toxic discharges into its rivers and, depending on which study you believe, ranks either forty-third or forty-seventh on spending on environmental programs.

Dr. Burkholder has regularly warned that unless serious pollution prevention measures were taken, North Carolina ran the risk of witnessing a serious Pfiesteria bloom, with all the accompanying human health and environmental consequences that entailed. Last summer and fall, that prophecy came true.

A period of heavy rains in July caused larger-than- usual soil and nutrient run-offs into the Neuse River. Newspaper headlines screamed, "Swine sewage sweeps downstream," and "25 million gallons lost at hog farm." Fish began dying: thousands within the first week or two and between seven million and eleven million after four months. People living along the riverside began complaining of festering sores, weight loss and stomach cramps. In the water, Dr. Burkholder found Pfiesteria. State officials, with one eye on North Carolina's tourist industry and another on the mining and hog farming lobbies, refused to accept there was a problem, or to issue a health warning. One spokesman accused Dr. Burkholder of turning "Pfiesteria into hysteria." Onslow County commissioner Sam Hewitt called on state officials to "silence" Dr. Burkholder and her fellow scientists, adding that "I'd like to take a rubber hose to some of them."

Finally, in early October, with the number of dead fish climbing into the millions, officials closed a seventeen- mile stretch of the Neuse River and issued a series of health warnings. By late November, a spokesman for North Carolina's Department of the Environment, Health and Natural Resources (DEHNR) told E that Pfiesteria did indeed appear to be the primary agent of the fish deaths, and that the state was looking again at the problem of hog effluent. But state epidemiologist Dr. Michael Moser asserted that surveys of physicians and veterinarians, and interviews with those claiming to suffer symptoms, "revealed no pattern of increased or unusual illnesses in humans or animals," and stated that there was "no evidence that Pfiesteria's toxin affects anything other than fish".

JoAnn Burkholder responds that a likely reason that physicians might be reporting few new illnesses is that Pfiesteria has been around for years, possibly causing these same symptoms all the time, but that it is only now, since the organism has been identified and with increased effluent discharges creating a more favorable environment for its growth, that people are paying attention.

Neuse River keeper Rick Dove agrees: "I remember in the mid-seventies, long before I took this job, or had heard of Dr. Burkholder or Pfiesteria, that waste was being pumped into one of the rivers here, and fish were dying then and both fish and people were getting sores. I had sores, and I had short-term memory loss like Dr. Burkholder reported later. As for there being no pattern in symptoms now: well, I'm only a layman, but I see the sores that these people are reporting -- people who've never seen each other or spoken to each other, a lot of the time, and they look the same to me. The problem is, those folks in the Health Department were doing all their surveys over the telephone from Raleigh; they were doing stuff like calling people who had been with me in a boat on the river for only thirty minutes or so, and asking them if they had any symptoms, and of course they didn't, so these guys were saying, "See, there's no evidence that people are contracting strange symptoms." What they needed to be doing was coming down here, seeing these people for themselves, looking at the people who were spending a lot of time near the river and contracting these symptoms, and making their judgments based on that."

The Pfiesteria outbreak ended in late October. But Pfiesteria hasn't gone away, merely returned to the sediment, there to wait until conditions are ripe for the next outbreak. And although North Carolina may be doing the best it can to create those conditions, Pfiesteria need not necessarily show up there next. So far, it been found as far south as the Gulf of Mexico and as far north as Delaware Bay.

And although Pfiesteria has yet to be found outside of the United States, harmful algal blooms (or HABs) involving different phytoplankton species have apparently been spreading and increasing in frequency in recent years. Species which have never before been identified, or which have previously been known to occur only infrequently, have erupted in massive blooms all over the planet, in places as diverse as Scandinavia, New Zealand, Japan and the North Sea. In addition to fish kills, some of these toxic algae can cause memory loss, diarrhea, paralysis and even death in humans; Dr. Paul Epstein of Harvard Medical School has even tentatively identified some algal blooms with a resurgence of cholera in South America. Not all these blooms can be definitively tied to nutrient pollution. Other factors may include natural cycles, climate change, or over-fishing, either by themselves or in combination. But according to Dr. Ted Smayda of the University of Rhode Island, "the evidence certainly does suggest that by putting more and more effluent into coastal waters, we are helping create a comfortable environment for these creatures. We need to be more careful about where we place agricultural sites and we can certainly reduce the amount of nutrients we place into the water. It's the prudent, conservative thing to do."