Pfiesteria piscicida and ulcerative mycosis of Atlantic menhaden - Currentstatus of understanding

Ulcerative lesions in estuarine finfish are associated with a variety of pa rasitic, bacterial. and fungal infectious agents as well as water quality a nd other abiotic stress factors. Atlantic menhaden Brevoortia tyrannus are a severely affected species typically exhibiting solitary. perianal. focal. deep, granulomatous lesions: containing oomycete hyphae. intense recent em phasis in the scientific literature and in the popular press has been place d on Pfiesteria-like dinoflagellates and their toxins as the causative agen ts for ulcerative finfish lesions in cast coast estuaries of the United Sta res. Dramatic descriptive terms for Pfiesteria, including "phantom," "ambus h-predator" and "the cell from hell." capable of affecting humans. have app eared in scientific journals and the: news media. However, there is no scie ntific evidence to date that supports a single, causal relationship between the presence of toxic Pfiesteria-like dinoflagellates and fish kills or th e associated ulcerative lesions. This is due, at least in part, to the diff iculty of maintaining toxic Pfiesteria-like dinoflagellates in clonal cultu re and, in part, to the presence of other microorganisms in laboratory cult ure systems. Further, there is at present no toxin-specific probe to identi fy Pfiesteria toxins in estuarine environments during fish frills, nor has Pfiesteria been isolated from fish lesions. Yet, based on the limited publi shed scientific evidence and the popular press coverage. there have been ri ver closures. notable economic Losses, and public alarm due to Pfiesteria. Future research into agents infectious to menhaden, such as Aphanomyces (Oo mycetes) and toxin-producing estuarine inhabitant like Pfiesteria, is neede d. These organisms and the disease processes in which they are implicated m ay also serve as markers for overall estuarine condition. Control of microo rganisms, including Pfiesteria, to improve finfish health in estuaries is u nlikely. However, using the presence of these microorganisms and their Atla ntic menhaden hosts as sentinels to help monitor water quality may be a via ble approach to assist future estuarine management.