DATE: Saturday, August 9, 1997              TAG: 9708090309

SECTION: LOCAL                   PAGE: B3   EDITION: FINAL 

SOURCE: BY MARIE JOYCE, STAFF WRITER 

                                            LENGTH:   94 lines

MAJOR FISH KILL FORCES CLOSURE OF LOWER POCOMOKE RIVER A MARINE BIOLOGIST SAYS THE VIRULENT CELL MAY ALSO INHABIT HAMPTON ROADS WATERS.

A five-mile stretch of the lower Pocomoke River that borders Maryland and Virginia was closed after thousands of fish died and people ignored a warning to stay out of the water.

The case prompted Virginia health officials Friday to urge people not to swim in any waters experiencing a fish kill.

``It makes sense to avoid water contact in a situation like that,'' said Suzanne Jenkins, assistant state epidemiologist for Virginia.

Since a large kill was detected Wednesday near Shelltown, Md., 3,000 to 11,000 fish have died, all on the Maryland side of the river. Maryland officials closed the river Thursday.

Many things can cause a fish kill, but the suspected culprit in the Pocomoke case is a highly adaptable, little-understood, one-celled organism called pfiesteria that has killed millions of fish in North Carolina. Dubbed ``the cell from hell'' by its discoverer, the creature can melt the flesh off live fish.

``We're not sure yet that pfiesteria is at work here. . . . There's been no definite evidence, so we are being cautious,'' state health Secretary Martin Wasserman said Thursday.

It is possible, said a local marine biologist, that the organism also inhabits Hampton Roads waters, although it has only been found here once.

The infected stretch of the Pocomoke borders to the east on Accomack County at the top of Virginia's Eastern Shore.

There's no proof that pfiesteria can hurt humans, but a small amount of anecdotal evidence suggests that it may trigger minor illness in people.

``Whether they are a health problem for people still is up for grabs,'' said Jenkins. ``We don't want to downplay the potential for something to cause human injury. On the other hand, we don't want to jump to conclusions and scare everybody.''

Researchers exposed to it in the lab have complained of temporary disorientation, memory loss, fatigue, nausea and skin lesions.

In experiments at Duke University Medical Center, the microorganism caused serious learning and memory problems in rats, although that doesn't mean it would have the same effect on people.

Ten people who have been in the Pocomoke River in recent weeks have complained of medical problems, including lesions and flulike symptoms, said Curtis Dickson, health officer for Maryland's Somerset County.

But, said Jenkins, ``You can't just take a few cases and make the assumption there's a connection.''

A study of waterman in North Carolina discovered no more lesions than normal on those working in pfiesteria-infested waters, she said.

Health officials do not consider pfiesteria a threat to fish and crabs taken from Chesapeake Bay, which connects to the Pocomoke. Even though it has been detected in parts of the Bay, it is not believed to be in toxic concentrations. There must be high levels of the microorganism to cause fish kills.

The organism was discovered in 1988 by North Carolina State University researcher JoAnne Burkholder. It is a dinoflagellate, an ancient, microscopic life form that acts sometimes like a plant and sometimes like an animal.

Amazingly adaptable, it rests in a cyst in sediment at the bottom of a body of water, said Harold Marshall, a marine biologist at Old Dominion University.

When swarms of fish pass by, chemicals in their excrement awaken the pfiesteria, and the microorganism changes into a mobile form. It attaches itself to the skin of fish, releasing a poison that causes the live fish's flesh to decompose. The pfiesteria absorbs the nutrients from the melting flesh.

So far, it has only been found once in Hampton Roads waters. Several years ago, Burkholder found a small number in samples from the York River, said Marshall.

``The possibility is high'' that it lurks in Hampton Roads waters, he said.

But Marshall warns people not to assume that a fish with lesions is a victim of pfiesteria. Viruses, fungi - even crab bites - can also cause piscine skin problems.

``We don't want to cause any hysterical situation with our local fishermen,'' he said.

ODU scientists and other researchers are looking for pfiesteria in local waters, part of a larger effort to monitor water quality and find microorganisms in and around Chesapeake Bay, he said.

Much of what's known about pfiesteria has been discovered in the lab.

It is elusive, earning the nickname ``the phantom dinoflagellate.'' After killing off massive numbers of fish, it retreats to the bottom of the river. By the time scientists arrive to investigate, the culprit is no longer found in the water.

The microorganism thrives in water polluted with nutrients and phosphates, said Marshall. These chemicals come primarily from sewage and run-off from farm land.

Maryland officials hope to know by early next week if the Pocomoke fish kill is the result of pfiesteria, said Maryland Natural Resources Secretary John Griffin.

The ban on the river is indefinite, said Dickson, the Somerset County health officer. ``When the state agencies advise us there is no longer a potential public health threat, we will lift the order.'' MEMO: The Associated Press contributed to this report.

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