Recently, the potential for subtle but serious chronic/sublethal impacts from dino-flagellates known as the toxic Pfiesteria complex on fish health as well as human health was realized during toxic outbreaks in several tributaries of the largest estuary on the U.S. mainland, Chesapeake Bay. Much more massive fish kills and epizootics by Pfiesteria also had occurred in the second largest estuary, the Albemarle-Pamlico, for nearly a decade before the Chesapeake outbreaks. In the proposed research we will continue to examine trophic controls on the complex life cycles of Pfiesteria piscicida, and will extend similar effort to characterize the life cycle of a second toxic Pfiesteria-like species (not yet formally named) that recently was identified from the Neuse and Pocomoke Estuaries in the Albemarle-Pamlico Estuarine Ecosystem and Chesapeake Bay, respectively. Using advanced video imaging and motion analysis software, we will obtain full photographic documentation of the stage transformations in the complex life cycle of the two species of fish ambush-predators, through manipulation of available prey (algae, bacteria, shellfish, finfish, mammalian tissues) and through alteration of environmental conditions (e.g., sudden temperature and salinity shock). This research will greatly improve recognition of Pfiesteria in field samples from fish kills/epizootics, and will also enhance general understanding of trophic controls on stage transformations and abundance of both known species in the toxic Pfiesteria complex.
