Impact/Purpose:

GENERIC RARE OBJECTIVE: The Regional Applied Research Effort (RARE) provides the Regions with a mechanism to address near term research needs through an ORD Laboratory/Center. Any applied research project that a Region identifies and that an ORD laboratory has the expertise to carry out will be considered if the three following conditions are met: 1) projects must be funded through an ORD Laboratory or Center, 2) the project must fall within with defined mission of the selected ORD Laboratory/Center, and 3) proposals must be research-oriented.

Description:

Recent evidence suggests that the estuarine dinofageflate, Pfiesteria piscicida, may release a toxin(s) which kills fish and adversely affects human health in laboratory and environmental settings. The potential for Pfresferia-like organisms to adversely impact estuarine ecosystem and human health, as well as the seafood and tourism industries, was demonstrated in the summer of 1997 as thousands of menhaden fish floated on the surface of the Pocomoke River near its junction with the Chesapeake Bay, and the Maryland state government and medical community responded to complaints of health effects from the citizenry. It has been suggested that environmental pollutants in the estuaries may be responsible for the increasing incidence of Pfiesteria-like events along the Eastern Seaboard during the 1990s. Most research on interactions between estuarine pollutants and the diversity and populace of algal, planktonic, and bacterial estuarine organisms has focused on nitrogen and phosphate. Although increases in nitrogen and phosphate concentrations are clearly linked with increases in some estuarine populations, it is not clear that these are the major causes of the increasing incidence of Pfiesteria-like events. The proposed research will address the potential impact of several agricultural runoff products on the diversity and populace of Pfresteria piscicida, its major prey (e.g cryptomonad, various green and chrysophyte flagellate taxa) and predators (e.g. various rotifers, zooplankton, ciliates), and on fish immunological function. The pollutants targeted for investigation are ethylene bisdithiocarbaniate fungicides used in crop and livestock production: Dithane (pure ethylene bisdithiocarbamate), Maneb (manganese plus ethylene bisdithiocarbamate), Zineb (zinc plus ethylene bisdithiocarbamate), and copper. Also, effects of zinc, used heavily in livestock production to boost immunological function, will be assessed. The US EPA's National Health and Environmental Effects Research Laboratory, in cooperation with US EPA Region III Office, Philadelphia, PA, intends to conduct research to address this issue. The project period will be 2 years and the research will be conducted in two phases. In Phase One, begun during the first year of the project, subsamples of amoeba and zoospores of PJiesteria piscicida (grown with five fish to induce toxicity) grown with several of Pfiesteria's major prey and predators will be used as replicates for batch culture experiments. In a series of experiments using concentration gradients of Dithane, Maneb, Zineb, copper, and zinc alone and in combination, Pfiesteria, its prey and its predators will be characterized for species, growth, population density, and cell production using scanning electron microscopic, reporter gene, and other techniques. Using dose-response information from Phase One on effects of the chemicals on Pfiesteria amoeba and zoospore forms, Phase Two, begun by the second year of the project, will examine effects of chemical and Pfiesteria toxin(s) stressors on fish immunological function. Pfiesteria at sub-lethal concentrations, its prey, and its predators will be raised with live fish in aquariums and treated with the chemicals alone and in combination at concentrations which do not adversely impact Pfiesteria's growth or toxicity. Standardized tests of fish immunological function (e.g. plaque forming cell assay, active immune assays including antibody production) will he administered to these fish, and the results will be compared to those from fish raised without exposure to the chemicals and/or Pfiesteria.

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