Pfiesteria Piscicidia, known to the popular media simply as "Pfiesteria", is a
Dinoflagellate organism that normally subsits on algae.
Pfiesteria has a life cycle of several stages, involving several distinct forms. It lies dormant on the bottom of a body of tidal salty water. Under certain conditions involving high nutrient levels, its population increases in an event known as a Pfiesteria "
bloom".
During some Pfiesteria blooms, the organism attacks
fish instead of its normal food, algae. It realeases a corrosive toxin in the fish's vicinity, which causes the fish's flesh to dissolve. This results in (usually fatal)
lesions on the fish's body.
Humans working or playing in the water during such a Pfiesteria bloom can also develop the lesions.
Two outbreaks of Pfiesteria involving massive fish kills have been widely publicized: In the tidal branches of
Pamlico Sound in
North Carolina, and in the Eastern
Chesapeake Bay in southeastern
Maryland. In both cases, the high nutrient levels responsible for the blooms have been linked to animal
manure1, which is either kept in containment ponds, which overflow due to rain, or sold to farmers to spread on their fields.
The industries involved dispute this, but what is indisputable is that the publicity from the events in Maryland caused demand for Maryland
seafood to plummet.
This event dealt a very hard blow to a seafood industry already reeling from overfishing and diseases.
1Pig manure in both cases, chicken manure in Maryland. It is an interesting fact that chickens are Maryland's largest agricultural product.