A four-year search for toxic Pfiesteria in Maryland waters has uncovered evidence that several other varieties of harmful algae, often fueled by pollution, may be seriously damaging bay life.
For years, scientists thought that the Chesapeake Bay and Maryland's coastal bays were mostly free from the harmful algae blooms that plague seriously polluted waters around the world - and are increasingly seen in state waters at this time of year.
But after Pfiesteria killed fish and sickened people on some Eastern Shore rivers in 1997, the State Department of Natural Resources fielded teams of biologists to look for signs of the toxic cell.
They found not only widespread traces of Pfiesteria, but also two previously unknown algae varieties capable of killing bay creatures. And they discovered that some familiar algae blooms are not as innocuous as once thought.
There is evidence that these algae can kill underwater grasses, prevent oyster larvae from hatching, contaminate shellfish and fray the web of bay life.
Unlike Pfiesteria, no other harmful algae found in state waters have been linked to human illnesses in the United States. But experts say the damage they are doing to Maryland's waterside way of life may be more serious in the long run.
Until Pfiesteria got the state's attention, "we really didn't recognize any other harmful algae blooms in the bay, even though we knew up and down the coast they were having problems," said Robert Magnien, director of the Department of Natural Resource's tidewater ecosystems division.
"Over the last few years, a lot of things have come to light," Magnien said. "We're discovering we're not as free of some of these problems as we might have thought."
Pfiesteria has been quiet for three years, with no major outbreaks and no rivers closed to protect the public's health. Tests by DNR biologists show low levels in lots of places, and Marylanders have learned to live with that.
But this summer, as in past years, at least three other harmful algae varieties are at work:
A brown tide organism that has devastated commercially valuable fisheries from Rhode Island to New Jersey was discovered in Maryland's coastal bays in 1999 and bloomed heavily in two places last year. At the end of last month, researchers were tracking two blooms even denser than last year's in salty Newport Bay and a portion of Chincoteague Bay.
