INSIDIOUS EFFECTS OF A TOXIC ESTUARINE DINOFLAGELLATE ON FISH SURVIVAL AND HUMAN HEALTH

The estuarine dinoflagellate Pfiesteria piscicida gen, et sp, nov. pro duces exotoxin(s) that can be absorbed from water or fine aerosols. Cu lture filtrate (0.22 mu m porosity filters, >250 toxic flagellated cel ls/ml) induces formation of open ulcerative sores, hemorrhaging, and d eath of finfish and shellfish. Human exposure to aerosols from ichthyo toxic cultures (greater than or equal to 2000 cells/ml) has been assoc iated with narcosis, respiratory distress with asthma-like symptoms, s evere stomach cramping, nausea, vomiting, and eye irritation with redd ening and blurred vision (hours to days); autonomic nervous system dys function [localized sweating, erratic heart beat (weeks)]; central ner vous system dysfunction [sudden rages and personality change (hours to days), and reversible cognitive impairment and short-term memory loss (weeks)]; and chronic effects including asthma-like symptoms, exercis e fatigue, and sensory symptoms (tingling or numbness in lips, hands, and feet months to years). Elevated hepatic enzyme levels and high pho sphorus excretion in one human exposure suggested hepatic and renal dy sfunction (weeks); easy infection and low counts of several T-cell typ es may indicate immune system suppression (months to years). Pfiesteri a piscicida is euryhaline and eurythermal, and in bioassays a nontoxic flagellated stage has increased under P enrichment (greater than or e qual to 100 mu g SRP/L suggesting a stimulatory role of nutrients. Pfi esteria-like dinoflagellates have been tracked to fish kill sites in e utrophic estuaries from Delaware Bay through the Gulf Coast. Our data point to a critical need to characterize their chronic effects on huma n health as well as fish recruitment, disease resistance, and survival .