EVIDENCE of the pernicious Pfiesteria piscicida microorganism in the mucky bottoms of five Maryland rivers is no big surprise, nor is it a cause for great alarm.
But it underlines the need to prevent waterway pollution, primarily from runoff of agricultural waste and chemicals, that encourages the tiny creature to turn toxic -- killing fish and causing short-term memory loss for humans.
Responding to large fish kills and reports of watermen's illness in 1997, Maryland required farms to develop surface runoff control plans by 2001 if they use chemical fertilizer and 2004 if they use manure.
The extent to which water pollution can trigger the dangerous form of Pfiesteria is unknown. But human water pollution is clearly one cause of toxic outbreaks -- along with weather conditions, the shape and flow of rivers, and available host fish for the parasite.
Pfiesteria aside, Maryland must crack down on surface runoff pollution of its sensitive waters to protect the health of the Chesapeake Bay system and its inhabitants.
That is why the state must hold firm against further delays for requiring farm runoff-control plans. The farm lobby, backed by an Agriculture Department panel, is pressing the General Assembly for a one-year delay in controls, claiming burdensome costs and a scarcity of technical expertise.
Pfiesteria expert JoAnn Burkholder believes the microorganism is in many state waterways. She recently found Pfiesteria for the first time in a river that flows into the Atlantic coastal bays near Ocean City and its tourist industry.
Experts note that no serious human illness has been tied to the Pfiesteria outbreak in the summer of 1997, when three Eastern Shore waterways were closed to fishing and recreation. Last year, a few small episodes in Maryland caused no fish kills or human harm.
Pfiesteria is in the Chesapeake system, but it is harmless most of the time, Dr. Burkholder says. The challenge is to limit human water pollution, so that the potentially toxic microbe remains benign.
Pub Date: 3/01/99