A toxic microorganism capable of killing fish and subsequently feeding off their flesh. Usually found in brackish waters. Pfiesteria has been associated with waters polluted with excessive nitrogen and phosphorus, but current scientific evidence is inconclusive and ongoing.

the estuarine toxin former that started my career in biotoxin illnesses. These dinoflagellates, from one of the oldest groups of living creatures, killed fish and made people sick in the Pocomoke (Md) River in 1997. When the State of Maryland said no one was made ill by Pfiesteria, my introduction to the Appearance of Good Science was initiated.

Pfiesteria is a genus of dinoflagellates, named for the late Dr. Lois Pfiester, a biologist who did much of the early research on the genus.