As the summer heats up Chesapeake Bay waters, a new kind of test to detect toxic marine microbes is sharpening Maryland efforts to predict fish-killing Pfiesteria. The test also helps medical studies of illness associated with the microbe.
David Oldach of the University of Maryland Biotechnology Institute (UMBI) reports that the test, applied to samples of mud or water, rapidly identifies Pfiesteria piscicida. In 1997, the microbe was linked with major fish kills in three Maryland rivers as well as previous fish kills in North Carolina. In addition, watermen near the fish kills and laboratory workers handling Pfiesteria cultures have suffered from illness ranging from skin lesions and stomach cramps to temporary memory loss and learning impairment lasting up to seven weeks.
In a recent issue of the Proceedings of the National Academy of Sciences, Oldach writes that the test is based on a "time-tested molecular biology method used commonly in medical research." The method, called HMA, is more often used to tease ut different strains of viruses in studies of Hepatitis C, AIDS, or gene mutations linked with cancer, or genetic diseases, such as cystic fibrosis.
Oldach and colleagues at UMBI's Institute of Human Virology (IHV) applied the method to samples of water and cultures of Pfiesteria-like microbes from Maine, Maryland, and North Carolina. The result is a DNA fingerprint of Pfiesteria used in the new test. The test can be adapted to detect other toxic marine organisms, he adds.
Last year in Maryland, experiments on the new test helped show that P. piscicida existed in at least 14 rivers and increased dramatically in July and August, according to Dave Goshorn, chief of the Maryland Department of Natural Resources' (DNR) Living Resource Assessment Program. "We found that the new test works so well, we will expand from 50 to 100 testing sites in the Bay area in 2000, in addition to any fish kill sites."