JoAnn Marie Burkholder (born 1953) is an American professor of aquatic ecology at the North Carolina State University, Raleigh.
She was responsible for identifying the cause, a dinoflagellate Pfiesteria piscicida and its toxins, of mass deaths of fish that posed a public health hazard.
The toxins from the dinoflagellate also affect humans, causing skin irritation, breathing difficulties and memory loss.
The fish-killing forms of Pfiesteria tended to be associated with high nutrient flows into waters from agricultural and urban waste.
The identity of the organism causing the fish kill and the circumstances under which it occurs led to a big public debate as well as within the biological community and was the subject of a book And the Waters Turned to Blood (1997) by Rodney Barker.